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Business Description and Basis of Presentation [Text Block]

1.	Organization and Business

Heron Therapeutics, Inc. is a biotechnology company focused on improving the lives of patients by developing best-in-class medicines that address major unmet medical needs. We are developing novel, patient-focused solutions that apply our innovative science and technologies to already-approved pharmacological agents. Our goal is to build on therapeutics with well-known pharmacology by improving their tolerability and efficacy as well as broadening their potential field of use.

We are currently developing pharmaceutical products for patients suffering from cancer or pain. SUSTOL is being developed for the prevention of both acute and delayed CINV associated with moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Our New Drug Application (“NDA”) for SUSTOL is pending review with the U.S. Food and Drug Administration (“FDA”), and was assigned a Prescription Drug User Fee Act (“PDUFA”) goal date of January 17, 2016. In January 2016, we were notified by the FDA that it would not take action on our SUSTOL NDA by the PDUFA date and that the FDA anticipates taking action in late February 2016. In addition to SUSTOL, we are currently developing several other pharmaceutical products for patients suffering from cancer or pain. HTX-019, also being developed for the prevention of CINV, is an intravenous formulation of aprepitant, a neurokinin-1 receptor antagonist. HTX-011, a long-acting formulation of the local anesthetic bupivacaine in a fixed-dose combination with the anti-inflammatory meloxicam, is being developed for the prevention of post-operative pain.

Liquidity

We have incurred significant operating losses and negative cash flows from operations, and we had an accumulated deficit of $412.8 million as of December 31, 2015. As of December 31, 2015, we had cash, cash equivalents and short-term investments of $131.2 million.

We believe that our current working capital is sufficient to fund operations through 2016, including pursuing regulatory approval for SUSTOL in the U.S. and, if approved, making significant investments to support commercialization, and completing Phase 2 and 3 clinical studies currently ongoing and expected to commence in 2016 relative to our HTX-011 and HTX-019 product candidates. In the event that we pursue preclinical and/or clinical development in other areas, potentially acquire other strategic assets, or if SUSTOL is not approved or has less commercial success than is expected, we may need to raise additional capital, and we may seek funds through various sources, including debt and equity offerings, corporate collaborations, bank borrowings, arrangements relating to assets, sale of royalty streams we may receive on our products or other financing methods or structures. The source, timing and availability of any financings will depend on market conditions, development program progress, interest rates and other factors. If we are unable to obtain sufficient financing on acceptable terms or otherwise, we may be required to reduce or defer our activities. Our capital requirements going forward will depend on numerous factors, including but not limited to: the scope, rate of progress, results and costs of preclinical testing and clinical trials; an approval decision by the FDA with respect to SUSTOL; the timing of and costs associated with the commercial launch of SUSTOL, if approved; the degree of commercial success of SUSTOL; the number and characteristics of product development programs we pursue and the pace of each program, including the timing of clinical trials; the time, cost and outcome involved in seeking other regulatory approvals; scientific progress in our research and development programs; the magnitude and scope of our research and development programs; our ability to establish and maintain strategic collaborations or partnerships for research, development, clinical testing, manufacturing and marketing of our product candidates; the cost and timing of establishing sales, marketing and distribution capabilities if we commercialize products independently; the cost of establishing clinical and commercial supplies of our product candidates and any products that we may develop; and general market conditions.

We may not be able to raise sufficient additional capital when we need it on favorable terms, or at all. The sale of additional equity in the future may be dilutive to our stockholders. If we are unable to obtain adequate funds on reasonable terms, we may be required to curtail operations significantly or to obtain funds by entering into financing, supply or collaboration agreements on unattractive terms.

Note 2 - Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2015

Significant Accounting Policies [Text Block]

2.	Summary of Significant Accounting Policies

Principles of Consolidation

The accompanying audited consolidated financial statements include the accounts of Heron Therapeutics, Inc. and its wholly owned subsidiary, Heron Therapeutics B.V., which was organized in the Netherlands in March 2015. Heron Therapeutics B.V. has no operations and no material assets or liabilities and there have been no significant transactions related to Heron Therapeutics B.V. since its inception.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and disclosures made in the accompanying notes to the financial statements. Our critical accounting policies that involve significant judgment and estimates include accrued clinical liabilities, income taxes and stock-based compensation. Actual results could differ materially from those estimates.

Cash,

Cash Equivalents

and Short-Term Investments

Cash and cash equivalents consist of cash and highly liquid investments with original maturities from purchase date of three months or less. Our bank accounts have been placed under a control agreement in accordance with our Senior Secured Convertible Notes (“Convertible Notes”).

Short-term investments consist of securities with maturities from purchase date of greater than three months. We have classified our short-term investments as available-for-sale securities in the accompanying consolidated financial statements. Available-for-sale securities are stated at fair market value, with unrealized gains and losses reported in other comprehensive income (loss) and realized gains and losses included in interest income. The cost of securities sold is based on the specific-identification method. Interest and dividends on securities classified as available-for-sale are included in interest income.

Fair Value of Financial Instruments

Financial instruments, including cash and cash equivalents, receivables, prepaid expenses, other current assets, accounts payable and accrued expenses, are carried at cost, which is considered to be representative of their respective fair values because of the short-term maturity of these instruments.

Short-term available-for-sale investments are carried at fair value (see Note 3 for further details regarding the fair value of financial instruments)

. Our Convertible Notes outstanding at December 31, 2015 do not have a readily available ascertainable market value, however, the carrying value is considered to approximate its fair value.

Concentration of Credit Risk

Cash, cash equivalents and short-term investments are financial instruments which potentially subject us to concentrations of credit risk. We deposit our cash in financial institutions. At times, such deposits may be in excess of insured limits. We may also invest our excess cash in money market funds, corporate debt securities and commercial paper. We have established guidelines relative to our diversification of our cash investments and their maturities in an effort to maintain safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates.

Property and Equipment

Property and equipment is stated at cost less accumulated depreciation and amortization. Depreciation is calculated on a straight-line basis over the estimated useful lives of the assets (primarily five years). Leasehold improvements are stated at cost and amortized on a straight-line basis over the shorter of the estimated useful life of the asset or the lease term.

Impairment of Long-Lived Assets

If indicators of impairment exist, we assess the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through undiscounted future operating cash flows. If impairment is indicated, we measure the amount of such impairment by comparing the carrying value of the asset to the fair value of the asset and records the impairment as a reduction in the carrying value of the related asset with a corresponding charge to operating results. Estimating the undiscounted future cash flows associated with long-lived assets requires judgment and assumptions that could differ materially from actual results.

Accrued Clinical Liabilities

We review and accrue clinical costs based on work performed, which relies on estimates of the progress of the trials and the related expenses incurred. Clinical trial-related contracts vary significantly in duration, and may be for a fixed amount, based on the achievement of certain contingent events or deliverables, a variable amount based on actual costs incurred, capped at a certain limit, or contain a combination of these elements. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development costs, however, a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to our results of operations.

Research and Development Expenses

All costs of research and development are expensed in the period incurred. Research and development costs primarily consist of salaries and related expenses for personnel, stock-based compensation, fees paid to outside service providers and consultants, facilities costs and materials used in the clinical and preclinical trials and research and development.

Patent Costs

We incur outside legal fees in connection with filing and maintaining our various patent applications. All patent costs are expensed as incurred and are included in general and administrative expense in the consolidated statements of comprehensive loss.

Stock-Based Compensation Expense

We estimate the fair value of stock-based payment awards using the Black-Scholes option pricing model. This fair value is then amortized using the straight-line single-option method of attributing the value of stock-based compensation to expense over the requisite service periods of the awards. The Black-Scholes option pricing model requires the input of highly complex and subjective assumptions, including each option’s expected life and price volatility of the underlying stock.

As stock-based compensation expense is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on historical experience.

Warrants

We have issued warrants to purchase shares of our common stock in conjunction with certain equity financings. The terms of the warrants were evaluated to determine the appropriate classification as equity or a liability.

Income Taxes

Accounting Standard Codification No. 740,

Accounting for Uncertainty in Income Taxes

, clarifies the accounting for uncertain tax positions. This provision requires that we recognize the impact of a tax position in our consolidated financial statements if the position is more likely than not to be sustained upon examination and on the technical merits of the position. The total amount of unrecognized tax benefits, if recognized, would affect other tax accounts, primarily deferred taxes in future periods, and would not affect our effective tax rate since we maintain a full valuation allowance against its deferred tax assets (see Note 8 for further details).

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources.

Unrealized gains and losses on available-for-sale securities are included in other comprehensive net loss and represent the difference between our net loss and comprehensive net loss for all periods presented.

Earnings per Share

Basic earnings per share (“EPS”) is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration of common share equivalents. Diluted EPS is computed by dividing the net loss by the weighted-average number of common shares and common share equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, stock options, warrants and common stock underlying Convertible Notes are considered to be common stock equivalents and are only included in the calculation of diluted EPS when their effect is dilutive.

Because we have incurred a net loss for all periods presented in the consolidated statements of comprehensive loss, outstanding stock options, warrants and common stock underlying Convertible Notes are not included in the computation of net loss per share because their effect would be anti-dilutive.

The following table includes the number of outstanding stock options, warrants and common stock underlying Convertible Notes not included in the computation as of the dates shown below (in thousands):

	As of December 31 ,
	2015		2014		2013

Stock options outstanding		8,435		7,918		6,356
Warrants outstanding		3,565		4,108		3,969
Common stock underlying Convertible Notes outstanding		7,087		6,677		6,291

Recent Accounting Pronouncements

In November 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2015-17

Income Taxes - Balance Sheet Classification of Deferred Taxes

(“ASU 2015-17). ASU 2015-17 simplifies the classification of deferred tax assets and liabilities. ASU 2015-17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. ASU 2015-17 is effective for interim and annual periods beginning after December 15, 2016 and allows for early adoption using a full retrospective method or a prospective method. We plan to adopt the provisions of ASU 2015-17 in 2017. We do not expect the adoption of ASU 2015-17 to have a material impact on our results of operations or financial condition.

In January 2015, FASB issued ASU No. 2015-

, Income Statement—Extraordinary and Unusual Items (Subtopic 225-20)

(“ASU 2015-01”). ASU 2015-01 eliminates the concept of extraordinary items from GAAP. FASB concluded that ASU 2015-01 will not result in a loss of information because although ASU 2015-01 will eliminate the requirements in Subtopic 225-20 for reporting entities to consider whether an underlying event or transaction is extraordinary, the presentation and disclosure guidance for items that are unusual in nature or occur infrequently will be retained and will be expanded to include items that are both unusual in nature and infrequently occurring.

The amendments in

ASU 2015-01 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. A reporting entity may apply the amendments prospectively. A reporting entity also may apply the amendments retrospectively to all prior periods presented in the financial statements. We adopted the provisions of ASU 2015-01 in the first quarter of 2015, which did not have a material impact on our results of operations or financial condition.

In August 2014, FASB issued ASU No. 2014-15,

Presentation of Financial Statements – Going Concern (Subtopic 205-40)

(“ASU 2014-15”). ASU 2014-15 requires management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. Specifically, the amendments (1) provide a definition of the term substantial doubt, (2) require an evaluation every reporting period, including interim periods, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated, and (6) require an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). The amendments in ASU 2014-15 are effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. Early adoption is permitted. We plan to adopt the provisions of ASU 2014-15 in 2016. We do not expect the adoption of this ASU to have a material impact on our results of operations or financial condition.

In June 2014, FASB issued ASU No. 2014-12,

Compensation – Stock Compensation (Topic 718)

(“ASU 2014-12”). ASU 2014-12 requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. Earlier adoption is permitted. The amendments in ASU 2014-12 may either be applied (a) prospectively to all awards granted or modified after the effective date or (b) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earlier annual period presented in the financial statements and to all new or modified awards thereafter. We plan to adopt the provisions of ASU 2014-12 in the first quarter of 2016. We do not expect the adoption of this ASU to have a material impact on our results of operations or financial condition.

Note 3 - Fair Value Measurements

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Text Block]

3.	Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value, is as follows:

•

Level 1 — Quoted prices in active markets for identical assets or liabilities.

•

Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

We measure the following financial assets at fair value on a recurring basis. The fair values of these financial assets at December 31, 2015 (in thousands) were as follows:

	Fair Value Measurements at Reporting Date Using
			Quoted Prices in		Significant
			Active Markets		Other		Significant
	Balance at		for Identical		Observable		Unobservable
	December 31,		Assets		Inputs		Inputs
	201 5		(Level 1) *		(Level 2) *		(Level 3)
Money market funds	$	67,089	$	67,089	$	—	$	—
United States corporate debt securities		28,715		—		28,715		—
Foreign corporate debt securities		4,922		—		4,922		—
United States commercial paper		7,770		—		7,770		—
Foreign commercial paper		15,579		—		15,579		—
Total	$	124,075	$	67,089	$	56,986	$	—

*There were no significant transfers between level 1 and level 2 investments for the year ended December 31, 2015.

As of December 31, 2015, we had cash equivalents consisting of $1,000,000 of available-for-sale securities with contractual maturities of less than three months. Short-term investments consisting of approximately $55,986,000 of available-for-sale securities with contractual maturities of one year or less. For the year ended December 31, 2014, we did not hold any investment securities and our cash equivalents consisted of money market funds.

A company may elect to use fair value to measure accounts and loans receivable, available-for-sale and held-to-maturity securities, equity method investments, accounts payable, guarantees and issued debt. Other eligible items include firm commitments for financial instruments that otherwise would not be recognized at inception and non-cash warranty obligations where a warrantor is permitted to pay a third party to provide the warranty goods or services. If the use of fair value is elected, any upfront costs and fees related to the item such as debt issuance costs must be recognized in earnings and cannot be deferred. The fair value election is irrevocable and generally made on an instrument-by-instrument basis, even if a company has similar instruments that it elects not to measure based on fair value. Unrealized gains and losses on existing items for which fair value has been elected are reported as a cumulative adjustment to beginning retained earnings and any changes in fair value are recognized in earnings. We have elected to not apply the fair value option to our financial assets and liabilities.

We consider the carrying amount of cash and cash equivalents, receivables, prepaid expenses and other current assets, accounts payable and accrued liabilities to be representative of their respective fair values because of the short-term nature of those instruments.

Unrealized gains and losses associated with our investments, if any, are reported in stockholders’ equity. For the year ended December 31, 2015, we recorded approximately $40,000 in net unrealized losses associated with our short-term investments. There were no unrealized gains or losses for the years ended December 31, 2014 and 2013.

Realized gains and losses associated with our investments, if any, are reported in the statement of comprehensive loss. There were no realized gains or losses for the years ended December 31, 2015, 2014 and 2013.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Note 4 - Balance Sheet Details

12 Months Ended

Dec. 31, 2015

Supplemental Balance Sheet Disclosures [Text Block]

4.	Balance Sheet Details

Short-Term Investments

The following is a summary of our short-term, available-for-sale securities (in thousands):

	December 31, 201 5
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
United States corporate debt	$	28,750	$	—	$	(35	)	$	28,715
Foreign corporate debt		4,927		—		(5	)		4,922
United States commercial paper		7,770		—		—			7,770
Foreign commercial paper		15,579		—		—			15,579
Total	$	57,026	$	—	$	(40	)	$	56,986

The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. We regularly monitor and evaluate the realizable value of our marketable securities. We did not recognize any impairment losses for the year ended December 31, 2015.

Property and Equipment

Property and equipment is comprised of the following (in thousands):

	December 31,
	2015			2014
Scientific equipment	$	5,593		$	4,793
Computer equipment and software		1,272			1,133
Furniture, fixtures and office equipment		352			351
Leasehold improvements		1,384			1,376
		8,601			7,653
Less: accumulated depreciation and amortization		(5,552	)		(4,833	)
	$	3,049		$	2,820

Depreciation and amortization expense for the years ended December 31, 2015, 2014 and 2013 was approximately $734,000, $578,000 and $333,000, respectively.

During the year ended December 31, 2014, we recognized $905,000 as an impairment loss due to the write-down of a piece of manufacturing-related equipment. As of December 31, 2014, the estimated fair value of the equipment was approximately $115,000. In 2015, we sold the equipment for cash proceeds of $241,000.

Accrued Payroll and Employee Liabilities and Other Accrued

Expense

Accrued payroll and employee liabilities and other accrued expense consisted of the following (in thousands):

	December 31,
	20 15		2014
Accrued employee salaries and benefits	$	1,863	$	719
Accrued bonuses		2,965		2,012
Total accrued payroll and employee liabilities	$	4,828	$	2,731

	December 31,
	2015		2014
Accrued consulting and professional fees	$	3,914	$	1,775
Accrued accounts payable		36		886
Deferred rent		61		105
Other accrued liabilities		143		165
Total other accrued expense	$	4,154	$	2,931

Note 5 - Commitments and Contingencies

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Text Block]

5.	Commitments and Contingencies

Leases

We lease 26,067 square feet of laboratory, office and warehouse space in Redwood City, California under a lease expiring on November 30, 2016. We have the option to extend the lease for an additional three years. In addition, we currently lease 1,898 square feet of office space in Jersey City, New Jersey and 3,419 square feet of office space in San Diego, California. The lease for the Jersey City office space began on July 1, 2015 and expires on December 31, 2016, and the lease for the San Diego office space was extended in 2015 for an additional nine-month period ending on March 31, 2016. We believe our facilities are adequate and suitable for our current needs, and that we will be able to obtain new or additional leased space in the future when necessary.

We also lease certain office equipment under operating lease arrangements.

Annual future minimum lease payments as of December 31, 2015 are as follows (in thousands):

	Operating Leases
Years ended December 31,
2016	$	1,067
2017		3
2018		—
2019		—
2020		—
Thereafter		—
Total	$	1,070

Rent expense under all operating leases totaled approximately $1,502,000, $1,381,000 and $967,000 for the years ended December 31, 2015, 2014 and 2013, respectively.

Clinical Development Agreements

We have entered into agreements with various vendors for the research and development of product candidates, which are generally cancellable anytime at our option. Under the terms of these agreements, the vendors provide a variety of services including conducting preclinical development, research, manufacturing clinical compounds, enrolling and recruiting patients, monitoring studies, data analysis and regulatory filing assistance. Payments under these agreements typically include fees for services and reimbursement of expenses. In addition, under certain agreements, we are subject to penalties in the event we permanently discontinue performance under these agreements.

Purchase Obligations

At December 31, 2015, our purchase obligations of $3,851,000 primarily consisted of commitments with third-party manufacturers in connection with the manufacturing of SUSTOL, as well as commitments with various vendors for clinical and preclinical studies. Approximately $3,192,000 of the total purchase obligations were not included in our consolidated financial statements for the year ended December 31, 2015. We intend to use our current financial resources to fund our commitments under these purchase obligations.

Note 6 - Convertible Notes to Related Parties

12 Months Ended

Dec. 31, 2015

Debt Disclosure [Text Block]

6.	Convertible Notes to Related Parties

In April 2011, we entered into a Securities Purchase Agreement for a private placement of up to $4.5 million in Convertible Notes. We received a total of $4.3 million, net of issuance costs, from the issuance of these Convertible Notes.

The Convertible Notes are secured by substantially all of our assets, including placing our bank and investment accounts under a control agreement. The Convertible Notes bear interest at 6% per annum, payable quarterly in cash or in additional principal amount of Convertible Notes, at the election of the purchasers. The Convertible Notes mature on May 2, 2021, however, the holders of the Convertible Notes may require prepayment of the Convertible Notes at any time, at each holder’s option.

The Convertible Notes are convertible into shares of our common stock at a rate of 1,250 shares for every $1,000 of principal and accrued interest due under the Convertible Notes. There is no right to convert the Convertible Notes to the extent that, after giving effect to such conversion, the holder would beneficially own in excess of 9.99% of our outstanding common stock. Each holder of the Convertible Notes can increase or decrease this beneficial ownership conversion limit by written notice to us, which will not be effective until 61 days after delivery of the notice.

As of December 31, 2015, we were in compliance with all covenants under the Convertible Notes. Upon the occurrence of an event of default under the Convertible Notes, the holders of the Convertible Notes have the right to require us to redeem all or a portion of their Convertible Notes.

In 2011, we filed a registration statement with the Securities and Exchange Commission (“SEC”) to register for resale 3.5 million shares underlying the Convertible Notes. The registration statement was declared effective on July 29, 2011. The Convertible Note holders have agreed to waive their right to require us to maintain the effectiveness of the registration statement and to register the additional shares underlying the Convertible Notes until they provide notice otherwise.

The Convertible Notes contain an embedded conversion feature that was in-the-money on the issuance dates. Based on an effective fixed conversion rate of 1,250 shares for every $1,000 of principal and accrued interest due under the Convertible Notes, the total conversion benefit at issuance exceeded the loan proceeds. Therefore, a debt discount was recorded in an amount equal to the face value of the Convertible Notes on the issuance dates and we began amortizing the resultant debt discount over the respective 10-year term of the Convertible Notes. During the year ended December 31, 2015, accrued interest of approximately $328,000 was paid-in-kind and rolled into the Convertible Note principal balance, which resulted in an additional debt discount of approximately $328,000. For the years ended December 31, 2015, 2014 and 2013, interest expense relating to the stated rate was approximately $333,000, $314,000 and $295,000, respectively, and interest expense relating to the amortization of the debt discount was approximately $624,000, $573,000 and $533,000, respectively.

As of December 31, 2015, the carrying value of the Convertible Notes was approximately $2,222,000, which is comprised of the $5,669,000 principal amount of the Convertible Notes outstanding, less debt discount of $3,447,000. If the $5,669,000 principal amount of Convertible Notes is converted, we would issue 7,086,560 shares of our common stock.

Note 7 - Stockholders' Equity

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note Disclosure [Text Block]

7 .	Stockholders’ Equity

Amendments to Articles of Incorporation

–

Reverse Stock Split

Effective January 13, 2014, we amended our Certificate of Incorporation to change our name to Heron Therapeutics, Inc. and effected a 1-for-20 reverse split of our outstanding common stock. The name change and Reverse Stock Split were approved by our stockholders on September 19, 2013. As a result of the Reverse Stock Split, we amended our Certificate of Incorporation to reduce the total authorized shares of our common stock from 1,500,000,000 to 75,000,000 shares.

2013 Common Stock Offering

In November 2013, we sold approximately 7.7 million shares of our common stock at a public offering price of $8.00 per share. We received total net proceeds of approximately $57.8 million (net of approximately $3.9 million in issuance costs).

2014 Common Stock Offering

In June 2014, we sold approximately 4.8 million shares of our common stock at a public offering price of $11.75 per share. In addition, as a component of the offering, we sold 600,000 pre-funded warrants to purchase shares of our common stock at a public offering price of $11.74 per share. The pre-funded warrants have an exercise price of $0.01 per share and expire on June 30, 2021. We received total net proceeds of approximately $58.9 million (net of approximately $4.0 million in issuance costs) from the sale of the common stock and the pre-funded warrants.

2015 Common Stock Offering

In June 2015, we sold approximately 5.5 million shares of our common stock at a public offering price of approximately $24.75 per share. We received total net proceeds of approximately $128.2 million (net of approximately $8.4 million in issuance costs) from the sale of the common stock.

Warrants

Private Placement Warrants

In June 2011, we sold shares of common stock and warrants to purchase common stock in a private placement. A total of 4.0 million warrants to purchase common stock at an exercise price of $3.60 per share were issued as part of this private placement. The warrants were immediately exercisable and expire on July 1, 2016. The warrants may be exercised for cash only, or, if a registration statement is not then effective and available for the resale of the shares of common stock issuable upon exercise of the warrants, by surrender of such warrant, or a portion of such warrant, by way of cashless exercise. There is no right to exercise the warrants to the extent that, after giving effect to such exercise the holder would beneficially own in excess of 9.99% of our outstanding shares of common stock or such other limit as may be designated by any particular purchaser. Each holder of the warrants can amend or waive the foregoing limitation by written notice to us, with such waiver taking effect only upon the expiration of a 61-day notice period.

During the year ended December 31, 2015, warrant holders exercised 343,813 warrants under the cashless exercise provision in the warrant agreement, which resulted in the net issuance of 285,713 shares of common stock and no net cash proceeds to us. During the year ended December 31, 2014, warrant holders exercised 460,706 warrants under the cashless exercise provision in the warrant agreement, which resulted in the net issuance of 303,614 shares of common stock and no net cash proceeds to us. During the year ended December 31, 2013, we received $0.6 million for cash exercises of these warrants.

Outstanding Warrants

The following table summarizes all warrants outstanding as of December 31, 2015:

	Number of Shares Outstanding		Exercise Price		Expiration Date
Issued to private placement investors in July 2011		2,965,477	$	3.60	07/01/2016
Issued in a public offering in June 2014		600,000	$	0.01	06/30/2021
Total warrants outstanding		3,565,477

The weighted-average exercise price of warrants outstanding as of December 31, 2014 was $3.00.

Common Stock Reserved for Future Issuance

Shares of our common stock reserved for future issuance as of December 31, 2015 were as follows:

	Number of Shares
Stock options outstanding		8,434,988
Stock options available for grant		3,880,849
Employee stock purchase plan		99,532
Warrants outstanding		3,565,477
Common stock underlying Convertible Notes outstanding		7,086,560
Total shares reserved for future issuance		23,067,406

Employee Stock Purchase Plan

In 1997 our stockholders approved our Employee Stock Purchase Plan (the “ESPP”). In December 2007, May 2009, June 2011, May 2014 and May 2015, our stockholders authorized increases in the number of shares reserved for issuance under the ESPP by 5,000, 10,000, 25,000, 25,000 and 100,000 shares, respectively, for a total of 175,000 shares reserved at December 31, 2015. Under the terms of the ESPP, employees can elect to have up to a maximum of 10% of their base earnings withheld to purchase our common stock. The purchase price of the stock is 85% of the lower of the closing prices for our common stock on: (i) the first trading day in the enrollment period, as defined in the ESPP, in which the purchase is made, or (ii) the purchase date. The length of the enrollment period is six months. Enrollment dates are the first business day of May and November. Approximately 36% of eligible employees participated in the ESPP in 2015. Under the ESPP, we issued 30,361, 12,028 and 5,630 shares in 2015, 2014 and 2013, respectively. The weighted-average exercise price per share of the purchase rights exercised during 2015, 2014 and 2013 was $8.46, $7.59 and $6.12, respectively. As of December 31, 2015, 75,468 shares of common stock have been issued under the ESPP and 99,532 shares of common stock are available for future issuance.

Stock Option Plans

We currently have one stock option plan from which we can grant options and restricted stock awards to employees, officers, directors and consultants. In December 2007, the stockholders approved our 2007 Equity Incentive Plan (the “2007 Plan”) at which time a maximum of 150,000 shares of common stock were available for grant. In May 2010, June 2011, May 2014 and May 2015, our stockholders approved amendments to our 2007 Plan to increase the maximum number of shares of common stock available for grant by 100,000, 4,500,000, 1,750,000 and 4,300,000 shares of common stock, respectively, resulting in an aggregate of 10,800,000 shares of common stock authorized for issuance as of December 31, 2015. At December 31, 2015, there were 3,880,849 shares available for future grant under the 2007 Plan. Any shares that are issuable upon exercise of options granted that expire, are cancelled, or that we receive pursuant to a net exercise of options, are available for future grant and issuance.

We also granted stock options and restricted stock awards under the 2002 Stock Incentive Plan (the “2002 Plan”) in prior years. The remaining shares available to be granted under the 2002 Plan expired in February 2012.

In 2014, 2013 and 2012, we granted options to certain employees outside of our stockholder approved stock option plans. All options to purchase our common stock were granted with an exercise price that equals fair market value of the underlying common stock on the grant dates and expire no later than ten years from the date of grant. The options are exercisable in accordance with vesting schedules that generally provide for them to be fully vested and exercisable four years after the date of grant, provided, however, that we have also issued stock options awards that are subject to performance vesting requirements. All stock option grants issued outside of our stockholder approved plans have been registered on Form S-8 with the SEC.

A summary of our stock option activity and related data follows:

	Outstanding Options
				Weighted-
				Average
	Number of			Exercise
	Shares			Price
Balance at December 31, 2012		4,323,874		$	8.46
Granted		4,256,971			8.08
Exercised		(537,029	)		5.20
Cancelled		(1,688,135	)		9.45
Balance at December 31, 2013		6,355,681			8.22
Granted		3,181,001			9.40
Exercised		(756,593	)		6.34
Cancelled		(862,085	)		9.88
Balance at December 31, 2014		7,918,004			8.69
Granted		2,134,505			28.95
Exercised		(1,042,343	)		9.15
Cancelled		(575,178	)		10.42
Balance at December 31, 2015		8,434,988		$	13.64

For the year ended December 31, 2015, option holders exercised 1,042,343 stock options resulting in cash proceeds to us of approximately $9.5 million.

For the year ended December 31, 2015, options cancelled (included in the above table) consisted of 503,343 options forfeited with a weighted-average exercise price of approximately $9.16 and 71,835 options expired with a weighted-average exercise price of approximately $19.24.

As of December 31, 2015, options exercisable have a weighted-average remaining contractual term of 6.7 years. The total intrinsic value of stock option exercises, which is the difference between the exercise price and closing price of our common stock on the date of exercise, during the years ended December 31, 2015 and 2014, was approximately $13,882,000 and $3,377,000, respectively. As of December 31, 2015 and 2014, the total intrinsic value of options outstanding and exercisable was approximately $46,603,000 and $14,654,000, respectively, which is the difference between the exercise price and closing price of our common stock.

	Years Ended December 31,
	2015				2014				2013
			Weighted-				Weighted-				Weighted-
			Average				Average				Average
			Exercise				Exercise				Exercise
	Options		Price		Options		Price		Options		Price
Exercisable at end of year		2,587,392	$	8.72		2,237,901	$	9.01		1,770,597	$	8.67
Options vested or expected to vest		8,059,481	$	13.38		7,841,074	$	8.69		6,292,296	$	8.22

Exercise prices and weighted-average remaining contractual lives for the options outstanding as of December 31, 2015 were:

												Weighted-
						Weighted-						Average
						Average		Weighted-				Exercise
						Remaining		Average				Price of
Options		Range of				Contractual		Exercise		Options		Options
Outstanding		Exercise Prices				Life (in years)		Price		Exercisable		Exercisable
	702,903		$3.80	–	$7.00		6.31	$	5.92		466,373	$	5.38
	2,302,688			$7.20			7.33		7.20		711,687		7.20
	2,047,712		$7.61	–	$9.05		8.30		8.91		711,561		8.84
	1,702,732		$9.20	–	$28.30		7.23		14.89		692,974		12.17
	1,678,953		$28.73	–	$128.00		9.71		30.23		4,797		42.60
	8,434,988		$3.80	–	$128.00		7.94		13.64		2,587,392		8.72

On December 31, 2015, we had reserved 8,434,988 shares of common stock for future issuance upon exercise of outstanding options granted under the 2002 Plan and the 2007 Plan, as well as the non-plan grants.

Valuation and Expense Information

The following table summarizes stock-based compensation expense related to stock-based payment awards granted pursuant to all of our equity compensation arrangements for the years ended December 31, 2015, 2014 and 2013 (in thousands):

	December 31,
	2015		2014		2013
Research and development	$	4,701	$	3,329	$	2,562
General and administrative		9,659		4,738		8,328
Stock-based compensation expense included in operating expenses	$	14,360	$	8,067	$	10,890

As of December 31, 2015, there was $63,865,000 of total unrecognized compensation cost related to non-vested, stock-based payment awards granted under all of our equity compensation plans and all non-plan option grants. Total unrecognized compensation cost will be adjusted for future changes in estimated forfeitures. We expect to recognize this compensation cost over a weighted-average period of 2.3 years.

For the years ended December 31, 2015, 2014 and 2013, we estimated the fair value of each option grant and ESPP purchase right on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

Options:

	December 31,
	2015			2014			2013
Risk-free interest rate		1.7	%		1.9	%		1.1	%
Dividend yield		—	%		—	%		—	%
Volatility		92.7	%		99.0	%		104.2	%
Expected life (years)		6			6			6

ESPP:

	December 31,
	2015			2014			2013
Risk-free interest rate		0.1	%		0.1	%		0.1	%
Dividend yield		—	%		—	%		—	%
Volatility		86.7	%		53.8	%		76.0	%
Expected life (months)		6			6			6

The weighted-average fair value of options granted was $21.92, $7.40 and $6.53 for the years ended December 31, 2015, 2014 and 2013, respectively.

The weighted-average fair value of shares purchased through the ESPP was $8.23, $3.06 and $3.01 for the years ended December 31, 2015, 2014 and 2013, respectively.

The risk-free interest rate assumption is based on observed interest rates on United States Treasury debt securities with maturities close to the expected term of our employee and director stock options and ESPP purchases.

The dividend yield assumption is based on our history and expectation of dividend payouts. We have never paid dividends on its common stock and we do not anticipate paying dividends in the foreseeable future.

We used our historical stock price to estimate volatility.

The expected life of employee and director stock options represents the average of the contractual term of the options and the weighted-average vesting period, as permitted under the simplified method. We have elected to use the simplified method, as we do not have enough historical exercise experience to provide a reasonable basis upon which to estimate the expected term. The expected life for the ESPP purchase rights is six months, which represents the length of each purchase period.

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 4
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 3
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Note 8 - Income Taxes

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Text Block]

8 .	Income Taxes

For the years ended December 31, 2015, 2014 and 2013, we did not record a provision for income taxes because we have incurred operating losses for all three years.

Deferred income tax assets and liabilities arising from differences between accounting for financial statement purposes and tax purposes, less valuation allowance at year-end are as follows (in thousands):

	December 31,
	201 5			201 4
Deferred tax assets:
Net operating loss carryforward	$	94,465		$	59,513
Research and development credits		11,181			7,667
Stock-based compensation		6,726			5,128
Other, net		1,345			964
Total deferred tax assets		113,717			73,272
Valuation allowance for net deferred tax assets		(113,717	)		(73,272	)
Net deferred taxes	$	—		$	—

Taxes on income vary from the statutory federal income tax rate applied to earnings before tax on income as follows (in thousands):

	December 31,
	2015			2014			2013
Statutory federal income tax rate of 34%	$	(33,181	)	$	(25,965	)	$	(18,796	)
Stock-based compensation expense		894			551			513
NOL not benefitted		31,935			25,085			17,983
Other, net		352			329			300
Provision for taxes	$	—		$	—		$	—

A valuation allowance is provided when it is more likely than not that the deferred tax assets will not be realized. We have established a valuation allowance to offset net deferred tax assets at December 31, 2015 and 2014 due to the uncertainty of realizing future tax benefits from our net operating loss carryforwards and other deferred tax assets. The net change in the total valuation allowance for the year ended December 31, 2015 and 2014 was an increase of approximately $40,445,000 and $32,035,000, respectively.

At December 31, 2015, we had federal and California state net operating loss (“NOL”) carryforwards of approximately $242,769,000 and $233,305,000, respectively, expiring beginning in 2018 for federal and 2017 for California state purposes. Approximately $4,235,000 of federal NOLs and $4,235,000 of state NOLs relate to stock-based compensation deductions in excess of book expense, the tax effect of which would be to credit additional paid-in capital, if realized. At December 31, 2015, we had federal and California state research credit carryforwards of approximately $7,434,000 and $5,639,000, respectively, expiring beginning in 2022 for federal. The California state credits can be carried forward indefinitely.

Internal Revenue Code section 382 places a limitation on the amount of taxable income that can be offset by NOL carryforwards after a change in control (generally greater than 50% change in ownership) of a loss corporation. California has similar rules. Generally, after a control change, a loss corporation cannot deduct NOL carryforwards in excess of the Section 382 limitation. We have performed an IRC Section 382 analysis and determined there were ownership changes in 2007, 2011, and 2013. We are currently in the process of completing the IRC Section 382 analysis for 2015 and we do not expect an ownership change for the year ended December 31, 2015. The limitation in the Federal and state carryforwards associated with the NOL and credit carryforwards reduce the deferred tax assets, which are further offset by a full valuation allowance. The limitation can result in the expiration of the NOLs and credit carryforwards available as of December 31, 2015 before utilization.

We file U.S. and state income tax returns with varying statutes of limitations. The tax years from 1998 to 2015 remain open to examination due to the carryover of unused NOL carryforwards and tax credits.

For benefits to be realized, a tax position must be more likely than not to be sustained upon examination. The amount recognized is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement. It is our policy to recognize interest and penalties related to income tax matters in income tax expense. As of December 31, 2015 and 2014, we had no accrued interest and penalties related to uncertain tax positions.

As of December 31, 2015 and 2014, we had unrecognized tax benefits of $120,000, and the amount that would impact our effective tax rate, before the consideration of the valuation allowance, is $120,000. We do not expect any material changes to the estimated amount of liability associated with its uncertain tax positions within the next 12 months.

Note 9 - Employee Benefit Plan

12 Months Ended

Dec. 31, 2015

Pension and Other Postretirement Benefits Disclosure [Text Block]

9 .	Employee Benefit Plan

We have a defined contribution 401K plan (the “Plan”) covering substantially all of our employees. In the past three calendar years, we made matching cash contributions equal to 50% of each participant’s contribution during the Plan year up to a maximum amount equal to the lesser of 3% of each participant’s annual compensation or $7,950, $7,800 and $7,650 for the years 2015, 2014 and 2013, respectively. Such amounts were recorded as expense in the corresponding years. We may also contribute additional discretionary amounts to the Plan as we may determine. For the years ended December 31, 2015, 2014 and 2013, we contributed to the Plan approximately $251,000, $181,000 and $134,000, respectively. No discretionary contributions have been made to the Plan since its inception.

Note 10 - Summary of Quarterly Consolidated Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information [Text Block]

10 .	Summary of Quarterly Consolidated Financial Data (unaudited)

The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2015 and 2014:

	2015
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Operating expenses:
Research and development	$	14,504		$	16,175		$	14,241		$	16,263
General and administrative		5,856			6,839			8,250			14,797
Loss from operations		(20,360	)		(23,014	)		(22,491	)		(31,060	)
Interest income		22			26			61			65
Interest expense		(232	)		(237	)		(242	)		(247	)
Other expense		—			118			—			—
Net loss	$	(20,570	)	$	(23,107	)	$	(22,672	)	$	(31,242	)
Basis and diluted net loss per share	$	(0.70	)	$	(0.74	)	$	(0.63	)	$	(0.87	)

	2014
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Operating expenses:
Research and development	$	11,628		$	14,279		$	14,731		$	14,195
General and administrative		5,694			4,512			4,222			5,300
Loss from operations		(17,322	)		(18,791	)		(18,953	)		(19,495	)
Interest income		—			—			—			3
Interest expense		(216	)		(220	)		(224	)		(227	)
Other expense		—			—			(17	)		(905	)
Net loss	$	(17,538	)	$	(19,011	)	$	(19,194	)	$	(20,624	)
Basis and diluted net loss per share	$	(0.74	)	$	(0.78	)	$	(0.66	)	$	(0.71	)

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2015

Accounting Policies [Abstract]

Consolidation, Policy [Policy Text Block]

Principles of Consolidation

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

Cash, Cash Equivalents, and Short-Term Investments [Policy Text Block]

Cash,

Cash Equivalents

and Short-Term Investments

Fair Value Measurement, Policy [Policy Text Block]

Fair Value of Financial Instruments

Short-term available-for-sale investments are carried at fair value (see Note 3 for further details regarding the fair value of financial instruments)

. Our Convertible Notes outstanding at December 31, 2015 do not have a readily available ascertainable market value, however, the carrying value is considered to approximate its fair value.

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Credit Risk

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block]

Impairment of Long-Lived Assets

Clinical Trial Accruals [Policy Text Block]

Accrued Clinical Liabilities

Research and Development Expense, Policy [Policy Text Block]

Research and Development Expenses

Legal Costs, Policy [Policy Text Block]

Patent Costs

Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]

Stock-Based Compensation Expense

Warrants Issued in Equity Financings [Policy Text Block]

Warrants

Income Tax, Policy [Policy Text Block]

Income Taxes

Accounting Standard Codification No. 740,

Accounting for Uncertainty in Income Taxes

Comprehensive Income, Policy [Policy Text Block]

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources.

Earnings Per Share, Policy [Policy Text Block]

Earnings per Share

	As of December 31 ,
	2015		2014		2013

Stock options outstanding		8,435		7,918		6,356
Warrants outstanding		3,565		4,108		3,969
Common stock underlying Convertible Notes outstanding		7,087		6,677		6,291

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

In November 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2015-17

Income Taxes - Balance Sheet Classification of Deferred Taxes

In January 2015, FASB issued ASU No. 2015-

, Income Statement—Extraordinary and Unusual Items (Subtopic 225-20)

The amendments in

In August 2014, FASB issued ASU No. 2014-15,

Presentation of Financial Statements – Going Concern (Subtopic 205-40)

In June 2014, FASB issued ASU No. 2014-12,

Compensation – Stock Compensation (Topic 718)

Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	As of December 31 ,
	2015		2014		2013

Stock options outstanding		8,435		7,918		6,356
Warrants outstanding		3,565		4,108		3,969
Common stock underlying Convertible Notes outstanding		7,087		6,677		6,291

Note 3 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Fair Value Measurements at Reporting Date Using
			Quoted Prices in		Significant
			Active Markets		Other		Significant
	Balance at		for Identical		Observable		Unobservable
	December 31,		Assets		Inputs		Inputs
	201 5		(Level 1) *		(Level 2) *		(Level 3)
Money market funds	$	67,089	$	67,089	$	—	$	—
United States corporate debt securities		28,715		—		28,715		—
Foreign corporate debt securities		4,922		—		4,922		—
United States commercial paper		7,770		—		7,770		—
Foreign commercial paper		15,579		—		15,579		—
Total	$	124,075	$	67,089	$	56,986	$	—

Note 4 - Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2015

Available-for-sale Securities [Table Text Block]

	December 31, 201 5
			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
United States corporate debt	$	28,750	$	—	$	(35	)	$	28,715
Foreign corporate debt		4,927		—		(5	)		4,922
United States commercial paper		7,770		—		—			7,770
Foreign commercial paper		15,579		—		—			15,579
Total	$	57,026	$	—	$	(40	)	$	56,986

Property, Plant and Equipment [Table Text Block]

	December 31,
	2015			2014
Scientific equipment	$	5,593		$	4,793
Computer equipment and software		1,272			1,133
Furniture, fixtures and office equipment		352			351
Leasehold improvements		1,384			1,376
		8,601			7,653
Less: accumulated depreciation and amortization		(5,552	)		(4,833	)
	$	3,049		$	2,820

Schedule of Accrued Liabilities [Table Text Block]

	December 31,
	20 15		2014
Accrued employee salaries and benefits	$	1,863	$	719
Accrued bonuses		2,965		2,012
Total accrued payroll and employee liabilities	$	4,828	$	2,731

	December 31,
	2015		2014
Accrued consulting and professional fees	$	3,914	$	1,775
Accrued accounts payable		36		886
Deferred rent		61		105
Other accrued liabilities		143		165
Total other accrued expense	$	4,154	$	2,931

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

Note 5 - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

	Operating Leases
Years ended December 31,
2016	$	1,067
2017		3
2018		—
2019		—
2020		—
Thereafter		—
Total	$	1,070

Note 7 - Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Number of Shares Outstanding		Exercise Price		Expiration Date
Issued to private placement investors in July 2011		2,965,477	$	3.60	07/01/2016
Issued in a public offering in June 2014		600,000	$	0.01	06/30/2021
Total warrants outstanding		3,565,477

Common Stock Reserved for Future Issuance [Table Text Block]

	Number of Shares
Stock options outstanding		8,434,988
Stock options available for grant		3,880,849
Employee stock purchase plan		99,532
Warrants outstanding		3,565,477
Common stock underlying Convertible Notes outstanding		7,086,560
Total shares reserved for future issuance		23,067,406

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Outstanding Options
				Weighted-
				Average
	Number of			Exercise
	Shares			Price
Balance at December 31, 2012		4,323,874		$	8.46
Granted		4,256,971			8.08
Exercised		(537,029	)		5.20
Cancelled		(1,688,135	)		9.45
Balance at December 31, 2013		6,355,681			8.22
Granted		3,181,001			9.40
Exercised		(756,593	)		6.34
Cancelled		(862,085	)		9.88
Balance at December 31, 2014		7,918,004			8.69
Granted		2,134,505			28.95
Exercised		(1,042,343	)		9.15
Cancelled		(575,178	)		10.42
Balance at December 31, 2015		8,434,988		$	13.64

Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable [Table Text Block]

	Years Ended December 31,
	2015				2014				2013
			Weighted-				Weighted-				Weighted-
			Average				Average				Average
			Exercise				Exercise				Exercise
	Options		Price		Options		Price		Options		Price
Exercisable at end of year		2,587,392	$	8.72		2,237,901	$	9.01		1,770,597	$	8.67
Options vested or expected to vest		8,059,481	$	13.38		7,841,074	$	8.69		6,292,296	$	8.22

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

												Weighted-
						Weighted-						Average
						Average		Weighted-				Exercise
						Remaining		Average				Price of
Options		Range of				Contractual		Exercise		Options		Options
Outstanding		Exercise Prices				Life (in years)		Price		Exercisable		Exercisable
	702,903		$3.80	–	$7.00		6.31	$	5.92		466,373	$	5.38
	2,302,688			$7.20			7.33		7.20		711,687		7.20
	2,047,712		$7.61	–	$9.05		8.30		8.91		711,561		8.84
	1,702,732		$9.20	–	$28.30		7.23		14.89		692,974		12.17
	1,678,953		$28.73	–	$128.00		9.71		30.23		4,797		42.60
	8,434,988		$3.80	–	$128.00		7.94		13.64		2,587,392		8.72

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	December 31,
	2015		2014		2013
Research and development	$	4,701	$	3,329	$	2,562
General and administrative		9,659		4,738		8,328
Stock-based compensation expense included in operating expenses	$	14,360	$	8,067	$	10,890

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	December 31,
	2015			2014			2013
Risk-free interest rate		1.7	%		1.9	%		1.1	%
Dividend yield		—	%		—	%		—	%
Volatility		92.7	%		99.0	%		104.2	%
Expected life (years)		6			6			6

	December 31,
	2015			2014			2013
Risk-free interest rate		0.1	%		0.1	%		0.1	%
Dividend yield		—	%		—	%		—	%
Volatility		86.7	%		53.8	%		76.0	%
Expected life (months)		6			6			6

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

Note 8 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	201 5			201 4
Deferred tax assets:
Net operating loss carryforward	$	94,465		$	59,513
Research and development credits		11,181			7,667
Stock-based compensation		6,726			5,128
Other, net		1,345			964
Total deferred tax assets		113,717			73,272
Valuation allowance for net deferred tax assets		(113,717	)		(73,272	)
Net deferred taxes	$	—		$	—

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	December 31,
	2015			2014			2013
Statutory federal income tax rate of 34%	$	(33,181	)	$	(25,965	)	$	(18,796	)
Stock-based compensation expense		894			551			513
NOL not benefitted		31,935			25,085			17,983
Other, net		352			329			300
Provision for taxes	$	—		$	—		$	—

Note 10 - Summary of Quarterly Consolidated Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of Quarterly Financial Information [Table Text Block]

	2015
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Operating expenses:
Research and development	$	14,504		$	16,175		$	14,241		$	16,263
General and administrative		5,856			6,839			8,250			14,797
Loss from operations		(20,360	)		(23,014	)		(22,491	)		(31,060	)
Interest income		22			26			61			65
Interest expense		(232	)		(237	)		(242	)		(247	)
Other expense		—			118			—			—
Net loss	$	(20,570	)	$	(23,107	)	$	(22,672	)	$	(31,242	)
Basis and diluted net loss per share	$	(0.70	)	$	(0.74	)	$	(0.63	)	$	(0.87	)

	2014
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(In thousands, except per share amounts)
Operating expenses:
Research and development	$	11,628		$	14,279		$	14,731		$	14,195
General and administrative		5,694			4,512			4,222			5,300
Loss from operations		(17,322	)		(18,791	)		(18,953	)		(19,495	)
Interest income		—			—			—			3
Interest expense		(216	)		(220	)		(224	)		(227	)
Other expense		—			—			(17	)		(905	)
Net loss	$	(17,538	)	$	(19,011	)	$	(19,194	)	$	(20,624	)
Basis and diluted net loss per share	$	(0.74	)	$	(0.78	)	$	(0.66	)	$	(0.71	)

Note 1 - Organization and Business (Details Textual) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Retained Earnings (Accumulated Deficit)	$ (412,828,000)	$ (315,237,000)
Cash, Cash Equivalents, and Short-term Investments	$ 131,200,000

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Available-for-sale Securities, Gross Unrealized Loss	$ 40,000	$ 0	$ 0
Available-for-sale Securities, Gross Unrealized Gain		$ 0	$ 0
Property, Plant and Equipment, Useful Life	5 years

Note 2 - Equity Excluded From Calculation of Diluted Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Shares excluded (in shares)	8,435	7,918	6,356
Warrant [Member]
Shares excluded (in shares)	3,565	4,108	3,969
Convertible Debt Securities [Member]
Shares excluded (in shares)	7,087	6,677	6,291

Note 3 - Fair Value Measurements (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Available-for-sale Securities, Current	$ 55,986,000	$ 0
Available-for-sale Securities, Gross Unrealized Loss	40,000	0	$ 0
Available-for-sale Securities, Gross Unrealized Gain		0	0
Available-for-sale Securities, Gross Realized Gains	0	0	0
Available-for-sale Securities, Gross Realized Losses	0	$ 0	$ 0
Cash Equivalents, at Carrying Value	$ 1,000,000

Note 3 - Financial Assets Measured on a Recurring Basis (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value	$ 67,089
Money Market Funds [Member]
Assets, fair value	67,089
Domestic Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	28,715
Domestic Corporate Debt Securities [Member]
Assets, fair value	28,715
Foreign Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	4,922
Foreign Corporate Debt Securities [Member]
Assets, fair value	4,922
United States Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	7,770
United States Commercial Paper [Member]
Assets, fair value	7,770
Foreign Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	15,579
Foreign Commercial Paper [Member]
Assets, fair value	15,579
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	67,089
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	56,986
Assets, fair value	$ 124,075

Note 4 - Balance Sheet Details (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equipment [Member]
Asset Impairment Charges		$ 905,000
Assets Held-for-sale, Long Lived, Fair Value Disclosure		115,000
Proceeds from Sale of Property, Plant, and Equipment	$ 241,000
Asset Impairment Charges	0	905,000	$ 0
Depreciation	734,000	578,000	333,000
Proceeds from Sale of Property, Plant, and Equipment	$ 241,000

Note 4 - Available-for-sale Securities (Details)	12 Months Ended
Note 4 - Available-for-sale Securities (Details)	Dec. 31, 2015 USD ($)
Domestic Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	$ 28,750,000
Available-for-sale Securities, Gross Unrealized Gain
Net unrealized loss on short-term investments	(35,000)
Available-for-sale Securities, Current	28,715,000
Foreign Corporate Debt Securities [Member]
Available-for-sale securities, amortized cost	4,927,000
Available-for-sale Securities, Gross Unrealized Gain
Net unrealized loss on short-term investments	(5,000)
Available-for-sale Securities, Current	4,922,000
United States Commercial Paper [Member]
Available-for-sale securities, amortized cost	7,770,000
Available-for-sale Securities, Gross Unrealized Gain
Net unrealized loss on short-term investments
Available-for-sale Securities, Current	7,770,000
Foreign Commercial Paper [Member]
Available-for-sale securities, amortized cost	15,579,000
Available-for-sale Securities, Gross Unrealized Gain
Net unrealized loss on short-term investments
Available-for-sale Securities, Current	15,579,000
Available-for-sale securities, amortized cost	57,026,000
Available-for-sale Securities, Gross Unrealized Gain
Net unrealized loss on short-term investments	(40,000)
Available-for-sale Securities, Current	$ 55,986,000

Note 4 - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Equipment [Member]
Property, plant, and equipment, gross	$ 5,593	$ 4,793
Computer Equipment [Member]
Property, plant, and equipment, gross	1,272	1,133
Furniture and Fixtures [Member]
Property, plant, and equipment, gross	352	351
Leasehold Improvements [Member]
Property, plant, and equipment, gross	1,384	1,376
Property, plant, and equipment, gross	8,601	7,653
Less: accumulated depreciation and amortization	(5,552)	(4,833)
	$ 3,049	$ 2,820

Note 4 - Accrued Payroll, Employee Liabilites, and Other Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued employee salaries and benefits	$ 1,863	$ 719
Accrued bonuses	2,965	2,012
Total accrued payroll and employee liabilities	4,828	2,731
Accrued consulting and professional fees	3,914	1,775
Accrued accounts payable	36	886
Deferred rent	61	105
Other accrued liabilities	143	165
Total other accrued expense	$ 4,154	$ 2,931

Note 5 - Commitments and Contingencies (Details Textual)	12 Months Ended
	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Redwood City [Member]
Area of Real Estate Property \| ft²	26,067
Jersey City [Member]
Area of Real Estate Property \| ft²	1,898
San Diego [Member]
Area of Real Estate Property \| ft²	3,419
Operating Leases, Rent Expense \| $	$ 1,502,000	$ 1,381,000	$ 967,000
Purchase Obligation \| $	3,851,000
Unrecorded Unconditional Purchase Obligation \| $	$ 3,192,000

Note 5 - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2015 USD ($)
2016	$ 1,067
2017	3
2018
2019
2020
Thereafter
Total	$ 1,070

Note 6 - Convertible Notes to Related Parties (Details Textual)		1 Months Ended	12 Months Ended
	Jul. 29, 2011 shares	Apr. 30, 2011 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Convertible Debt Securities [Member] \| Common Stock [Member]
Debt Instrument Conversion Ratio Shares \| shares		1,250
Convertible Debt Securities [Member] \| In Case of Debt Conversion [Member]
Debt Instrument, Face Amount			$ 5,669,000
Debt Instrument, Convertible, Number of Equity Instruments			7,086,560
Convertible Debt Securities [Member]
Debt Instrument, Interest Rate, Stated Percentage		6.00%
Debt Instrument Conversion Ratio Multiple of Principal		$ 1,000
Beneficial Ownership after Conversion		9.99%
Notice Period Associated with Beneficial Ownership Percentage Limitation Convertible Notes		61 days
Paid-in-Kind Interest			$ 328,000
Debt Instrument, Increase (Decrease), Other, Net			328,000
Convertible Notes Payable, Related Parties, Current			2,222,000
Debt Instrument, Face Amount			5,669,000
Debt Instrument, Unamortized Discount			3,447,000
Convertible Debt Issuable in Connection with Private Placement		$ 4,500,000
Proceeds from Convertible Debt		$ 4,300,000
Common Shares Registered for Resale in Connection with Convertible Notes \| shares	3,500,000
Interest Expense, Debt, Excluding Amortization			333,000	$ 314,000	$ 295,000
Amortization of Debt Discount (Premium)			624,000	573,000	$ 533,000
Convertible Notes Payable, Related Parties, Current			$ 2,222,000	$ 1,598,000

Note 7 - Stockholders' Equity (Details Textual)		1 Months Ended									12 Months Ended			68 Months Ended	97 Months Ended
Note 7 - Stockholders' Equity (Details Textual)	Jan. 13, 2014	Jun. 30, 2015 USD ($) $ / shares shares	May 31, 2015 shares	Jun. 30, 2014 USD ($) $ / shares shares	May 31, 2014 shares	Nov. 30, 2013 USD ($) $ / shares shares	Jun. 30, 2011 $ / shares shares	May 31, 2010 shares	May 31, 2009 shares	Dec. 31, 2007 shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Sep. 13, 2013 shares	Sep. 12, 2013 shares
Private Placement 2011 [Member] \| Common Stock [Member]
Stock Issued During Period, Shares, New Issues											285,713	303,614
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised											343,813	460,706
Private Placement 2011 [Member]
Proceeds from Warrant Exercises \| $											$ 0		$ 600,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							4,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares							$ 3.60
Beneficial Ownership after Conversion							9.99%
Notice Period Associated with Beneficial Ownership Percentage Limitation Convertible Notes							61 days
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	20
Common Stock [Member]
Stock Issued During Period, Shares, New Issues		5,500,000		4,800,000		7,700,000
Sale of Stock, Price Per Share \| $ / shares		$ 24.75		$ 11.75		$ 8
Proceeds from Issuance of Common Stock \| $						$ 57,800,000
Payments of Stock Issuance Costs \| $		$ 8,400,000				$ 3,900,000
Proceeds from Issuance or Sale of Equity \| $		$ 128,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period											1,042,000	588,000	537,000
Common Stock and Prefunded Warrants [Member]
Payments of Stock Issuance Costs \| $				$ 4,000,000
Proceeds from Issuance or Sale of Equity \| $				$ 58,900,000
Pre-funded Warrants[Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				600,000
Share Price \| $ / shares				$ 11.74
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares				$ 0.01
Weighted Average [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares												$ 3
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized			100,000		25,000		25,000		10,000	5,000					175,000
Share-based Compensation Arrangement by Share-based Payment Award Maximum Employee Earnings with held to Purchase Common Stock Percent											10.00%
Share-based Compensation Arrangement by Share-based Payment Award Discount on Stock Price												85.00%
Share-based Compensation Arrangement by Share-based Payment Award Eligible Participants Percent											36.00%
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period											30,361	12,028	5,630
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price \| $ / shares											$ 8.46	$ 7.59	$ 6.12
Common Stock, Shares, Issued											75,468			75,468	75,468
Common Stock, Capital Shares Reserved for Future Issuance											99,532			99,532	99,532
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value \| $ / shares											$ 21.92	7.40	6.53
Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted-average Fair Value Price of Shares Purchased \| $ / shares											$ 8.23	$ 3.06	$ 3.01	$ 8.23	$ 8.23
Equity Incentive Plan 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized			4,300,000		1,750,000		4,500,000	100,000						10,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized										150,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant											3,880,849			3,880,849	3,880,849
Proceeds from Warrant Exercises \| $													$ 600,000
Common Stock, Shares Authorized											75,000,000	75,000,000		75,000,000	75,000,000	75,000,000	1,500,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights											3,565,477			3,565,477	3,565,477
Proceeds from Issuance or Sale of Equity \| $											$ 128,199,000	$ 58,916,000	$ 57,802,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price \| $ / shares											$ 9.15	$ 6.34
Common Stock, Shares, Issued											36,106,000	29,227,000		36,106,000	36,106,000
Common Stock, Capital Shares Reserved for Future Issuance											23,067,406			23,067,406	23,067,406
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant											3,880,849			3,880,849	3,880,849
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period											10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period											4 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period											1,042,343	756,593	537,029
Proceeds from Stock Options Exercised \| $											$ 9,535,000	$ 3,101,000	$ 2,793,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period											503,343
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price \| $ / shares											$ 9.16
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period											71,835
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price \| $ / shares											$ 19.24
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term											6 years 255 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value \| $											$ 13,882,000	3,377,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value \| $											$ 46,603,000	$ 14,654,000		$ 46,603,000	$ 46,603,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options											8,434,988			8,434,988	8,434,988
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $											$ 63,865,000			$ 63,865,000	$ 63,865,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition											2 years 109 days

Note 7 - Warrants Outstanding (Details)	Dec. 31, 2015 $ / shares shares
Private Placement, July 2011 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	2,965,477
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 3.60
Public Offering, June 2014 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	600,000
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 0.01
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	3,565,477

Note 7 - Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2015 shares
Stock options outstanding (in shares)	8,434,988
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	3,880,849
Employee stock purchase plan (in shares)	99,532
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	3,565,477
Common stock underlying Convertible Notes outstanding (in shares)	7,086,560
Total shares reserved for future issuance (in shares)	23,067,406

Note 7 - Option Summary (Details) - $ / shares	12 Months Ended
Note 7 - Option Summary (Details) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of shares outstanding (in shares)	7,918,004	6,355,681	4,323,874
Number of shares outstanding, weighted average exercise price (in dollars per share)	$ 8.69	$ 8.22	$ 8.46
Number of shares granted (in shares)	2,134,505	3,181,001	4,256,971
Number of shares granted, weighted average exercise price (in dollars per share)	$ 28.95	$ 9.40	$ 8.08
Number of shares exercised (in shares)	(1,042,343)	(756,593)	(537,029)
Number of shares cancelled (in shares)	(575,178)	(862,085)	(1,688,135)
Number of shares cancelled, weighted average exercise price (in dollars per share)	$ 10.42	$ 9.88	$ 9.45
Number of shares outstanding (in shares)	8,434,988	7,918,004	6,355,681
Number of shares outstanding, weighted average exercise price (in dollars per share)	$ 13.64	$ 8.69	$ 8.22
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 9.15	$ 6.34

Note 7 - Options Exercisable, Vested or Expected to Vest (Details) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Options exercisable at end of year (in shares)	2,587,392	2,237,901	1,770,597
Options exercisable at end of year, weighted average exercise price (in dollars per share)	$ 8.72	$ 9.01	$ 8.67
Options vested or expected to vest (in shares)	8,059,481	7,841,074	6,292,296
Options vested or expected to vest, weighted average exercise price (in dollars per share)	$ 13.38	$ 8.69	$ 8.22

Note 7 - Exercise Price Ranges (Details)	12 Months Ended
Note 7 - Exercise Price Ranges (Details)	Dec. 31, 2015 $ / shares shares
Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	702,903
Range of exercise prices, lower limit (in dollars per share)	$ 3.80
Range of exercise prices, upper limit (in dollars per share)	$ 7
Options outstanding, weighted-average remaining contractual life	6 years 113 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 5.92
Options exercisable (in shares) \| shares	466,373
Options exercisable, weighted-average exercise price (in dollars per share)	$ 5.38
Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	2,302,688
Options outstanding, weighted-average remaining contractual life	7 years 120 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 7.20
Options exercisable (in shares) \| shares	711,687
Options exercisable, weighted-average exercise price (in dollars per share)	$ 7.20
Exercise Price Range 3 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	2,047,712
Range of exercise prices, lower limit (in dollars per share)	$ 7.61
Range of exercise prices, upper limit (in dollars per share)	$ 9.05
Options outstanding, weighted-average remaining contractual life	8 years 109 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 8.91
Options exercisable (in shares) \| shares	711,561
Options exercisable, weighted-average exercise price (in dollars per share)	$ 8.84
Exercise Price Range 4 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	1,702,732
Range of exercise prices, lower limit (in dollars per share)	$ 9.20
Range of exercise prices, upper limit (in dollars per share)	$ 28.30
Options outstanding, weighted-average remaining contractual life	7 years 83 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 14.89
Options exercisable (in shares) \| shares	692,974
Options exercisable, weighted-average exercise price (in dollars per share)	$ 12.17
Exercise Price Range 5 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	1,678,953
Range of exercise prices, lower limit (in dollars per share)	$ 28.73
Range of exercise prices, upper limit (in dollars per share)	$ 128
Options outstanding, weighted-average remaining contractual life	9 years 259 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 30.23
Options exercisable (in shares) \| shares	4,797
Options exercisable, weighted-average exercise price (in dollars per share)	$ 42.60
Exercise Price Range 6 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	8,434,988
Range of exercise prices, lower limit (in dollars per share)	$ 3.80
Range of exercise prices, upper limit (in dollars per share)	$ 128
Options outstanding, weighted-average remaining contractual life	7 years 343 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 13.64
Options exercisable (in shares) \| shares	2,587,392
Options exercisable, weighted-average exercise price (in dollars per share)	$ 8.72
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options \| shares	8,434,988

Note 7 - Allocation of the Recognized Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Research and Development Expense [Member]
Share-based compensation expense	$ 4,701	$ 3,329	$ 2,562
General and Administrative Expense [Member]
Share-based compensation expense	9,659	4,738	8,328
Share-based compensation expense	$ 14,360	$ 8,067	$ 10,890

Note 7 - Option Valuation Assumptions (Details)	12 Months Ended
Note 7 - Option Valuation Assumptions (Details)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Risk-free interest rate	1.70%	1.90%	1.10%
Volatility	92.70%	99.00%	104.20%
Expected life (years)	6 years	6 years	6 years
Employee Stock Purchase Plan [Member]
Risk-free interest rate	0.10%	0.10%	0.10%
Volatility	86.70%	53.80%	76.00%
Expected life (years)	180 days	180 days	180 days

Note 8 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
Note 8 - Income Taxes (Details Textual) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Domestic Tax Authority [Member] \| Stock Compensation Plan [Member]
Operating Loss Carryforwards	$ 4,235,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards	242,769,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	7,434,000
State and Local Jurisdiction [Member] \| Stock Compensation Plan [Member]
Operating Loss Carryforwards	4,235,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	233,305,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	5,639,000
Income Tax Expense (Benefit)	0	$ 0	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0	0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	40,445,000	32,035,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 11,181,000	7,667,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		120,000
Unrecognized Tax Benefits		$ 120,000

Note 8 - Components of Defered Tax Assets (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforward	$ 94,465,000	$ 59,513,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	11,181,000	7,667,000
Stock-based compensation	6,726,000	5,128,000
Other, net	1,345,000	964,000
Total deferred tax assets	113,717,000	73,272,000
Valuation allowance for net deferred tax assets	(113,717,000)	(73,272,000)
Net deferred taxes	$ 0	$ 0

Note 8 - Provisions (Details) - USD ($)	12 Months Ended
Note 8 - Provisions (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statutory federal income tax rate of 34%	$ (33,181,000)	$ (25,965,000)	$ (18,796,000)
Stock-based compensation expense	894,000	551,000	513,000
NOL not benefitted	31,935,000	25,085,000	17,983,000
Other, net	352,000	329,000	300,000
Provision for taxes	$ 0	$ 0	$ 0

Note 8 - Provisions (Details) (Parentheticals)	12 Months Ended
Note 8 - Provisions (Details) (Parentheticals)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statutory federal income tax rate	0.34%	0.34%	0.34%

Note 9 - Employee Benefit Plan (Details Textual) - USD ($)	12 Months Ended			36 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Maximum [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	3.00%	3.00%	3.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%	50.00%	50.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount				$ 0
Defined Contribution Plan, Maximum Annual Contributions by Employer per Employee, Amount	$ 7,950	$ 7,800	$ 7,650
Defined Contribution Plan, Cost Recognized	$ 251,000	$ 181,000	$ 134,000

Note 10 - Summary Quarterly Results of Operations (Details) - USD ($)	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Operating expenses:
Research and development	$ 16,263,000	$ 14,241,000	$ 16,175,000	$ 14,504,000	$ 14,195,000	$ 14,731,000	$ 14,279,000	$ 11,628,000
General and administrative	14,797,000	8,250,000	6,839,000	5,856,000	5,300,000	4,222,000	4,512,000	5,694,000
Loss from operations	(31,060,000)	(22,491,000)	(23,014,000)	(20,360,000)	(19,495,000)	(18,953,000)	(18,791,000)	(17,322,000)
Interest income	65,000	61,000	26,000	22,000	3,000
Interest expense	(247,000)	(242,000)	(237,000)	(232,000)	(227,000)	(224,000)	(220,000)	(216,000)
Other expense			118,000		(905,000)	(17,000)
Net loss	$ (31,242,000)	$ (22,672,000)	$ (23,107,000)	$ (20,570,000)	$ (20,624,000)	$ (19,194,000)	$ (19,011,000)	$ (17,538,000)
Basis and diluted net loss per share (in dollars per share)	$ (0.87)	$ (0.63)	$ (0.74)	$ (0.70)	$ (0.71)	$ (0.66)	$ (0.78)	$ (0.74)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.