Geron (GERN) 10-Q 5 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 29, 2016
Document and Entity Information
Entity Registrant Name	GERON CORP
Entity Central Index Key	886,744
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		158,960,258
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 12,802	$ 21,248
Restricted cash	267	267
Marketable securities	96,846	92,524
Interest and other receivables	624	1,206
Prepaid assets	416	647
Total current assets	110,955	115,892
Noncurrent marketable securities	31,976	32,661
Property and equipment, net	212	207
Total assets	143,143	148,760
Current liabilities:
Accounts payable	396	160
Accrued compensation and benefits	1,619	2,974
Accrued collaboration charges	3,537	2,328
Accrued restructuring charges	35	52
Accrued liabilities	1,071	1,120
Total current liabilities	$ 6,658	$ 6,634
Commitments and contingencies
Stockholders' equity:
Common stock	$ 159	$ 159
Additional paid-in capital	1,073,515	1,070,567
Accumulated deficit	(937,229)	(928,387)
Accumulated other comprehensive income (loss)	40	(213)
Total stockholders' equity	136,485	142,126
Total liabilities and stockholders' equity	$ 143,143	$ 148,760

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
License fees and royalties	$ 749,000	$ 537,000
Operating expenses:
Research and development	5,033,000	4,987,000
Restructuring charges		406,000
General and administrative	4,793,000	4,600,000
Total operating expenses	9,826,000	9,993,000
Loss from operations	(9,077,000)	(9,456,000)
Unrealized gain on derivatives		16,000
Interest and other income	256,000	149,000
Interest and other expense	(21,000)	(24,000)
Net loss	$ (8,842,000)	$ (9,315,000)
Basic and diluted net loss per share (in dollars per share)	$ (0.06)	$ (0.06)
Shares used in computing basic and diluted net loss per share (in shares)	158,896,038	157,547,568

CONDENSED STATEMENTS OF COMPREH

CONDENSED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CONDENSED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (8,842)	$ (9,315)
Net unrealized gain on marketable securities	253	67
Comprehensive loss	$ (8,589)	$ (9,248)

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS CHANGE IN CASH AND CASH EQUIVALENTS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (8,842)	$ (9,315)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	21	9
Accretion and amortization on investments, net	284	629
Stock-based compensation for services by non-employees	50	67
Stock-based compensation for employees and directors	2,019	2,013
Amortization related to 401(k) contributions	53	154
Unrealized gain on derivatives		(16)
Changes in assets and liabilities:
Other current assets	813	(95)
Other current liabilities	24	(1,151)
Net cash used in operating activities	(5,578)	(7,705)
Cash flows from investing activities:
Purchases of property and equipment	(26)	(7)
Purchases of marketable securities	(46,751)	(78,869)
Proceeds from maturities of marketable securities	43,083	52,490
Net cash used in investing activities	(3,694)	(26,386)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	826	1,477
Net cash provided by financing activities	826	1,477
Net decrease in cash and cash equivalents	(8,446)	(32,614)
Cash and cash equivalents at the beginning of the period	21,248	42,796
Cash and cash equivalents at the end of the period	12,802	10,182
Supplemental Disclosure of Non-Cash Investing Activities:
Net unrealized gain on marketable securities	$ 253	$ 67

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The terms “Geron”, the “Company”, “we” and “us” as used in this report refer to Geron Corporation. The accompanying unaudited condensed financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management of Geron, all adjustments (consisting only of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 or any other period. These financial statements and notes should be read in conjunction with the financial statements for each of the three years ended December 31, 2015, included in the Company’s Annual Report on Form 10-K. The accompanying condensed balance sheet as of December 31, 2015 has been derived from audited financial statements at that date. Net Loss Per Share Basic net income (loss) per share is calculated by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the periods presented, without consideration for common stock equivalents. Diluted net income per share is calculated by adjusting the weighted-average number of shares of common stock outstanding for the dilutive effect of common stock equivalents outstanding for the periods presented, as determined using the treasury-stock method. Potential dilutive securities primarily consist of outstanding stock options, restricted stock awards, and warrants to purchase our common stock. Diluted net loss per share excludes common stock equivalents outstanding for the periods presented, as determined using the treasury-stock method, as their effect would be anti-dilutive, resulting in the same number of shares being used for the calculation of basic and diluted net loss per share. For all periods presented in the accompanying condensed statements of operations, the net loss applicable to common stockholders is equal to the reported net loss. Since we incurred a net loss for the three months ended March 31, 2016 and 2015, 3,593,074 and 4,122,123 common stock equivalents, respectively, related to outstanding stock options and restricted stock awards (as determined using the treasury-stock method at the estimated average market value) were excluded from the diluted net loss per share calculation as their effect would have been anti-dilutive . In addition, for the three months ended March 31, 2016 and 2015, 10,617,930 and 8,783,291 potentially dilutive securities, respectively, were excluded from the treasury-stock method and calculation of diluted net loss per share as their effect would have been anti-dilutive . Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On a regular basis, management evaluates these estimates and assumptions. Actual results could differ from those estimates. Fair Value of Financial Instruments Cash Equivalents and Marketable Securities We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. We are subject to credit risk related to our cash equivalents and marketable securities. We place our cash and cash equivalents in money market funds, commercial paper, corporate notes and cash operating accounts. Our marketable securities include U.S. government-sponsored enterprise securities, commercial paper and corporate notes with original maturities ranging from four to 24 months. We classify our marketable securities as available-for-sale. We record available-for-sale securities at fair value with unrealized gains and losses reported in accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses are included in interest and other income and are derived using the specific identification method for determining the cost of securities sold and have been insignificant to date. Dividend and interest income are recognized when earned and included in interest and other income in our condensed statements of operations. We recognize a charge when the declines in the fair values below the amortized cost basis of our available-for-sale securities are judged to be other-than-temporary. We consider various factors in determining whether to recognize an other-than-temporary charge, including whether we intend to sell the security or whether it is more likely than not that we would be required to sell the security before recovery of the amortized cost basis. Declines in market value associated with credit losses judged as other-than-temporary result in a charge to interest and other income. Other-than-temporary charges not related to credit losses are included in accumulated other comprehensive income (loss) in stockholders’ equity. We have not recorded any other-than-temporary impairment charges on our available-for-sale securities for the three months ended March 31, 2016 and 2015. See Note 2 on Fair Value Measurements. Revenue Recognition We recognize revenue for each unit of accounting when all of the following criteria have been met: (a) persuasive evidence of an arrangement exists, (b) delivery has occurred or services have been rendered, (c) the seller’s price to the buyer is fixed or determinable, and (d) collectability is reasonably assured. Amounts received prior to satisfying these revenue recognition criteria are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as noncurrent deferred revenue. License and/or Collaboration Agreements In addition to the exclusive collaboration and license agreement, or Collaboration Agreement, that we entered into with Janssen Biotech, Inc., or Janssen, in November 2014 (which is more fully described in Note 3 on Collaboration and License Agreement), we have entered into several license or collaboration agreements with various oncology, diagnostics, research tools and biologics production companies. Economic terms in these agreements may include non-refundable license payments in cash or equity securities, option payments in cash or equity securities, cost reimbursements, cost-sharing arrangements, milestone payments, royalties on future sales of products, or any combination of these items. In applying the appropriate revenue recognition guidance related to these agreements, we first assess whether the arrangement contains multiple elements. In this evaluation, we consider: (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires us to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis, and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in our control. In assessing whether an item has standalone value, we consider factors such as the research, manufacturing and commercialization capabilities of the collaboration partner or licensee and the availability of the associated expertise in the general marketplace. In addition, we consider whether the collaboration partner or licensee can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. We then apply the applicable revenue recognition criteria noted above to each of the separate units of accounting in determining the appropriate period and pattern of recognition. We determine how to allocate arrangement consideration to identified units of accounting based on the selling price hierarchy provided under relevant accounting guidance. The estimated fair value of deliverables under the arrangement may be derived using a best estimate of selling price if vendor-specific-objective evidence and third-party evidence are not available. Upfront non-refundable signing, license or non-exclusive option fees are recognized as revenue: (i) when rights to use the intellectual property have been delivered, if the license has standalone value from the other deliverables to be provided under the agreement, or (ii) over the term of the agreement if we have continuing performance obligations, as the arrangement would be accounted for as a single unit of accounting. When payments are received in equity securities, we do not recognize any revenue unless such securities are determined to be realizable in cash. At the inception of an arrangement that includes milestone payments, we assess whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether: (i) the consideration is commensurate with either the performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. We consider various factors, such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone and the level of effort and investment required to achieve the respective milestone, in making this assessment. There is considerable judgment involved in determining whether a milestone satisfies all of the criteria required to conclude that a milestone is substantive. Milestone payments for milestones that are considered substantive would be recognized as revenue in their entirety upon successful accomplishment of the milestone, assuming all other revenue recognition criteria are met. Milestone payments for milestones that are not considered substantive would be recognized as revenue over the remaining period of performance, assuming all other revenue recognition criteria are met. Royalties are recognized as earned in accordance with contract terms when royalties from licensees can be reasonably estimated and collectability is reasonably assured. If royalties cannot be reasonably estimated or collectability of a royalty amount is not reasonably assured, royalties are recognized as revenue when the cash is received. Revenue from commercial milestone payments is accounted for as royalties and recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. Cost-sharing expenses are recorded as earned or owed based on the performance requirements by both parties under the respective contracts. For arrangements in which we and our collaboration partner in the agreement are exposed to significant risks and rewards depending on the commercial success of the activity, we recognize payments between the parties on a net basis and record such amounts as a reduction or addition to research and development expense. For arrangements in which we have agreed to perform certain research and development services for our collaboration partner and are not exposed to significant risks and rewards depending on the commercial success of the activity, we recognize the respective cost reimbursements as revenue under the collaborative agreement as the related research and development services are rendered. Restricted Cash Restricted cash consists of funds maintained in a separate certificate of deposit account for credit card purchases. Research and Development Expenses Research and development expenses consist of expenses incurred in identifying, developing and testing product candidates resulting from our independent efforts as well as efforts associated with collaborations. These expenses include, but are not limited to, in-process research and development acquired in an asset acquisition and deemed to have no alternative future use, payroll and personnel expense, lab supplies, preclinical studies, clinical trials, including support for investigator-sponsored clinical trials, raw materials to manufacture clinical trial drugs, manufacturing costs for research and clinical trial materials, sponsored research at other labs, consulting, costs to maintain technology licenses, our proportionate share of research and development costs under cost-sharing arrangements with collaboration partners and research-related overhead. Research and development costs are expensed as incurred, including payments made under our collaboration and/or license agreements. For the clinical development activities being conducted by Janssen, we monitor patient enrollment levels and related activities to the extent possible through discussions with Janssen personnel and base our estimates on the best information available at the time. However, additional information may become available to us which would allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain. Depreciation and Amortization We record property and equipment at cost and calculate depreciation using the straight-line method over the estimated useful lives of the assets, generally four years. Leasehold improvements are amortized over the shorter of the estimated useful life or remaining term of the lease. Stock-Based Compensation We recognize stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting period. The following table summarizes the stock-based compensation expense included in operating expenses on our condensed statements of operations related to stock options, restricted stock awards and employee stock purchases for the three months ended March 31, 2016 and 2015 which was allocated as follows: Three Months Ended March 31, (In thousands) 2016 2015 Research and development $ $ Restructuring charges — General and administrative Stock-based compensation expense included in operating expenses $ $ In connection with a restructuring we announced in March 2015, the post-termination exercise period for certain stock options previously granted to employees affected by the restructuring was extended from 90 days to one year from their respective termination dates, subject to each employee’s continuous service until his/her specified termination date. The incremental value associated with these stock option modifications was recognized as non-cash stock-based compensation expense over each employee’s remaining service period with the Company and recorded as restructuring charges on our condensed statements of operations as reflected in the table above. See Note 4 on Restructuring for a further discussion of the March 2015 restructuring. As stock-based compensation expense recognized in our condensed statements of operations for the three months ended March 31, 2016 and 2015 is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures, but at a minimum, reflects the grant-date fair value of those awards that actually vested in the period. Forfeitures have been estimated at the time of grant based on historical data and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Stock Options We grant options with service-based vesting under our equity plans to employees, non-employee directors and consultants. The vesting period for employee options is generally four years. The fair value of options granted during the three months ended March 31, 2016 and 2015 has been estimated at the date of grant using the Black Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility 0.890 0.884 Risk-free interest rate 1.21% 1.70% Expected term 5.5 yrs 5.5 yrs Employee Stock Purchase Plan The fair value of employees’ purchase rights during the three months ended March 31, 2016 and 2015 has been estimated using the Black Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility range 0.684 0.721 to 1.392 Risk-free interest rate range 0.28% 0.11% to 0.25% Expected term range 12 mos 6 – 12 mos Dividend yield is based on historical cash dividend payments. The expected volatility is based on historical volatilities of our stock since traded options on Geron stock do not correspond to option terms and the trading volume of options is limited. The risk-free interest rate is based on the U.S. Zero Coupon Treasury Strip Yields for the expected term in effect on the date of grant for an award. The expected term of options is derived from actual historical exercise and post-vesting cancellation data and represents the period of time that options granted are expected to be outstanding. The expected term of employees’ purchase rights is equal to the purchase period. Restricted Stock Awards We have granted restricted stock awards to employees and non-employee directors with service-based vesting schedules that generally vest annually over four years. The fair value for service-based restricted stock awards is determined using the fair value of our common stock on the date of grant. The fair value is amortized as stock-based compensation expense over the requisite service period of the award, which is generally the vesting period, on a straight-line basis and is reduced for estimated forfeitures, as applicable. Non-Employee Stock-Based Awards For our non-employee stock-based awards, the measurement date on which the fair value of the stock-based award is calculated is equal to the earlier of: (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. We recognize stock-based compensation expense for the fair value of the vested portion of non-employee awards in our condensed statements of operations. Segment Information Our executive management team represents our chief decision maker. We view our operations as a single segment, the development of therapeutic products for oncology. As a result, the financial information disclosed herein materially represents all of the financial information related to our principal operating segment. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2014-09, or ASU 2014-09, which creates Accounting Standards Codification Topic 606, Revenue from Contracts with Customers , or Topic 606, and supersedes the revenue recognition requirements in Accounting Standards Codification Topic 605, Revenue Recognition , including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. In summary, the core principle of Topic 606 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. Companies are allowed to select between two transition methods: (1) a full retrospective transition method with the application of the new guidance to each prior reporting period presented, or (2) a retrospective transition method that recognizes the cumulative effect on prior periods at the date of adoption together with additional footnote disclosures. The amendments in ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, and early application is not permitted. We are currently evaluating the impact that the adoption of ASU 2014-09 will have on our financial statements and related disclosures and have not made any decision on the method of adoption. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes , or ASU 2015-17. Current generally accepted accounting principles requires an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. To simplify the presentation of deferred income taxes, ASU 2015-17 requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets of a tax paying component of an entity be offset and presented as a single amount is not affected by the amendments in this update. The amendments in this update are effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Earlier application is permitted for all entities as of the beginning of an interim or annual reporting period. We are currently evaluating the impact that the adoption of ASU 2015-17 will have on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) , or ASU 2016-02. ASU 2016-02 requires an entity to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. Recognition, measurement and presentation of expenses will depend on classification as a finance or operating lease. Certain quantitative and qualitative disclosures about leasing arrangements also are required. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The updated guidance requires a modified retrospective adoption. We are currently evaluating the impact that the adoption of ASU 2016-02 will have on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU 2016-09, which amends Accounting Standards Codification Topic 718, Compensation — Stock Compensation . ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods and early adoption is permitted. We are currently evaluating the impact of the adoption of ASU 2016-09 on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. With the exception of the standards discussed above, there have been no new accounting pronouncements not yet effective that have significance, or potential significance, to our financial statements.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2016
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	2 . FAIR VALUE MEASUREMENTS We categorize financial instruments recorded at fair value on our condensed balance sheets based upon the level of judgment associated with inputs used to measure their fair value. The categories are as follows: Level 1 — Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. An active market for an asset or liability is a market in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 — Inputs (other than quoted market prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 — Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Below is a description of the valuation methodologies used for financial instruments measured at fair value on our condensed balance sheets, including the category for such financial instruments. Cash Equivalents and Marketable Securities Certificates of deposit and money market funds are categorized as Level 1 within the fair value hierarchy as their fair values are based on quoted prices available in active markets. U.S. government-sponsored enterprise securities, commercial paper and corporate notes are categorized as Level 2 within the fair value hierarchy as their fair values are estimated by using pricing models, quoted prices of securities with similar characteristics or discounted cash flows. Cash equivalents, restricted cash and marketable securities by security type at March 31, 2016 were as follows: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Included in cash and cash equivalents: Money market funds $ $ — $ — $ Commercial paper — Corporate notes — — $ $ $ — $ Restricted cash: Certificate of deposit $ $ — $ — $ Marketable securities: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ $ ) $ Commercial paper (due in less than 1 year) ) Corporate notes (due in less than 1 year) ) Corporate notes (due in 1 to 2 years) ) $ $ $ ) $ Cash equivalents, restricted cash and marketable securities by security type at December 31, 2015 were as follows: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Included in cash and cash equivalents: Money market funds $ $ — $ — $ Government-sponsored enterprise securities — — Commercial paper — — Corporate notes — ) $ $ — $ ) $ Restricted cash: Certificate of deposit $ $ — $ — $ Marketable securities: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ — $ ) $ Commercial paper (due in less than 1 year) ) Corporate notes (due in less than 1 year) ) Corporate notes (due in 1 to 2 years) — ) $ $ $ ) $ Cash equivalents and marketable securities with unrealized losses at March 31, 2016 and December 31, 2015 were as follows: Less Than 12 Months 12 Months or Greater Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized (In thousands) Fair Value Losses Fair Value Losses Fair Value Losses As of March 31, 2016: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ ) $ — $ — $ $ ) Commercial paper (due in less than 1 year) ) — — ) Corporate notes (due in less than 1 year) ) ) ) Corporate notes (due in 1 to 2 years) ) — — ) $ $ ) $ $ ) $ $ ) As of December 31, 2015: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ ) $ — $ — $ $ ) Commercial paper (due in less than 1 year) ) — — ) Corporate notes (due in less than 1 year) ) ) ) Corporate notes (due in 1 to 2 years) ) — — ) $ $ ) $ $ ) $ $ ) The gross unrealized losses related to government-sponsored enterprise securities, commercial paper and corporate notes as of March 31, 2016 and December 31, 2015 were due to changes in interest rates. We determined that the gross unrealized losses on our cash equivalents and marketable securities as of March 31, 2016 and December 31, 2015 were temporary in nature. We review our investments quarterly to identify and evaluate whether any investments have indications of possible impairment. Factors considered in determining whether a loss is temporary include the length of time and extent to which the fair value has been less than the amortized cost basis and whether we intend to sell the security or whether it is more likely than not that we would be required to sell the security before recovery of the amortized cost basis. We currently do not intend to sell these securities before recovery of their amortized cost basis. Fair Value on a Recurring Basis The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of March 31, 2016 and indicates the fair value category assigned. Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs (In thousands) Level 1 Level 2 Level 3 Total Money market funds (1) $ $ — $ — $ Government-sponsored enterprise securities (3) — — Commercial paper (1)(2) — — Corporate notes (1)(2)(3) — — Total $ $ $ — $ The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of December 31, 2015 and indicates the fair value category assigned. Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs (In thousands) Level 1 Level 2 Level 3 Total Money market funds (1) $ $ — $ — $ Government-sponsored enterprise securities (1)(3) — — Commercial paper (1)(2) — — Corporate notes (1)(2)(3) — — Total $ $ $ — $ (1) Included in cash and cash equivalents on our condensed balance sheets. (2) Included in current portion of marketable securities on our condensed balance sheets. (3) Included in noncurrent portion of marketable securities on our condensed balance sheets.

COLLABORATION AND LICENSE AGREE

COLLABORATION AND LICENSE AGREEMENT	3 Months Ended
	Mar. 31, 2016
COLLABORATION AND LICENSE AGREEMENT
COLLABORATION AND LICENSE AGREEMENT	3. COLLABORATION AND LICENSE AGREEMENT In November 2014, we and Janssen entered into the Collaboration Agreement, under which we granted to Janssen exclusive worldwide rights to develop and commercialize imetelstat for all human therapeutic uses, including hematologic myeloid malignancies. Upon the effectiveness of the Collaboration Agreement, we received $35,000,000 from Janssen as an upfront payment, which we classified as deferred revenue upon receipt. Under the Collaboration Agreement, Janssen is wholly responsible for the development, manufacturing and commercialization of, and seeking regulatory approval for imetelstat worldwide. To that end, Janssen is currently proceeding with the development of imetelstat with two clinical trials: a Phase 2 trial in myelofibrosis, referred to as IMbark™, and a Phase 2/3 trial in myelodysplastic syndromes, referred to as IMerge™. Development costs for IMbark™ and IMerge™ are being shared between us and Janssen on a 50/50 basis. Additionally, under the terms of the Collaboration Agreement, we remain responsible for prosecuting, at Janssen’s direction, the patents licensed to Janssen at the time we entered into the Collaboration Agreement, with costs shared between us and Janssen on a 50/50 basis. The cost sharing arrangement with Janssen began in January 2015. As of March 31, 2016, accrued collaboration charges of $3,537,000 on our condensed balance sheet represent the net amount owed to Janssen for our proportionate share of research and development costs incurred by them under the Collaboration Agreement for the three months ended March 31, 2016. Following completion of the protocol specified primary analysis of IMbark™ or after a certain time period after the initiation of the first Phase 3 myelofibrosis study, if any, Janssen must notify us whether it elects to maintain its license rights and continue to advance the development of imetelstat in any indication. In the event that IMbark™ has been terminated early or suspended, Janssen must instead notify us of its decision by the date that is the later of 24 months from the initiation of IMerge™ or 24 months from the termination of IMbark™ or commencement of the suspension period, as applicable. In the event that Janssen elects to continue to maintain its license rights and advance the development of imetelstat in any indication within the applicable timeframe set forth in the Collaboration Agreement (such decision, the Continuation Decision), we then would have an option, or the U.S. Opt-In Rights, to share further U.S. development and promotion costs in exchange for higher tiered royalty rates and higher future development and regulatory milestone payments if imetelstat is successfully developed and approved. If we exercise the U.S. Opt-In Rights, then we and Janssen would share U.S. development and promotion costs beyond IMbark™ or IMerge™ on a 20/80 basis (Geron 20%, Janssen 80%), we would receive a $65,000,000 milestone payment, or the Continuation Fee, at the time of an affirmative Continuation Decision, and would be eligible to receive additional potential payments of up to $470,000,000 in development and regulatory milestones, up to $350,000,000 in sales milestones, and tiered royalties ranging from a mid-teens up to low twenties percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen. In addition, if we exercise the U.S. Opt-In Rights, we then would also have a separate option, or the U.S. Co-Promotion Option, to provide 20% of the U.S. selling effort with sales force personnel, in lieu of funding 20% of U.S. promotion costs, upon regulatory approval and commercial launch of imetelstat in the United States. Such co-promotion would be conducted under a Janssen prepared promotion plan, and in accordance with a co-promotion agreement to be agreed by the parties at the time of our exercise of the U.S. Co-Promotion Option. We would be responsible for all costs associated with establishing and maintaining a sales force in any conduct of such co-promotion. All product sales would be booked by Janssen. If we do not exercise the U.S. Opt-In Rights, then all further development and promotion costs beyond IMbark™ or IMerge™ would be borne by Janssen, we would receive the $65,000,000 Continuation Fee at the time of an affirmative Continuation Decision plus a $70,000,000 payment, or the Full U.S. Rights Fee, for Janssen’s retention of full U.S. rights to imetelstat, and would be eligible to receive additional potential payments of up to $415,000,000 in development and regulatory milestones, up to $350,000,000 in sales milestones, and tiered royalties ranging from a double-digit up to mid-teens percentage rate on worldwide net sales of imetelstat in any countries where regulatory exclusivity exists or there are valid claims under the patent rights exclusively licensed to Janssen. After an affirmative Continuation Decision by Janssen, the Collaboration Agreement would remain in effect until the expiration of the last-to-expire patent or the royalty obligations on sales of imetelstat cease, unless terminated earlier. If Janssen does not effect an affirmative Continuation Decision, then the Collaboration Agreement would terminate and all rights to the imetelstat program would revert to us. Janssen may terminate the Collaboration Agreement at any time for convenience or due to a safety-related concern. If a notice of termination from Janssen occurs, we would be entitled to certain continued operational support and cost sharing under various circumstances and all rights to the imetelstat program would revert to us. We concluded the license for exclusive worldwide rights to develop and commercialize imetelstat has standalone value to Janssen and that delivery of the license rights granted by us to Janssen, together with our performance of certain technology transfer-related activities under the Collaboration Agreement, represented the sole non-contingent deliverable under the Collaboration Agreement associated with the upfront payment. Therefore, we accounted for our delivery of the imetelstat license rights and our performance of the technology transfer-related activities as a single unit of accounting. During the third quarter of 2015, we completed performance of the technology transfer-related activities to Janssen as outlined under the Collaboration Agreement. Combining this performance with the delivery of the imetelstat license rights, we fully recognized the $35,000,000 upfront payment from Janssen as collaboration revenue on our condensed statements of operations in the third quarter of 2015. We have determined that each of the additional potential milestone payments to us under the Collaboration Agreement, including: (i) the Continuation Fee at the time of an affirmative Continuation Decision, (ii) the Full U.S. Rights Fee, if we do not exercise the U.S. Opt-In Rights and (iii) payments based on the achievement of certain development, regulatory or sales milestones, represent substantive milestones. Consequently, we will recognize revenue for these payments in their entirety upon successful accomplishment of the respective milestone. Royalties on future product sales of imetelstat, if successfully commercialized under the Collaboration Agreement, will be recognized as revenue when earned.

RESTRUCTURING

RESTRUCTURING	3 Months Ended
	Mar. 31, 2016
RESTRUCTURING
RESTRUCTURING	4. RESTRUCTURING With projected reduced operational demands as a result of the Collaboration Agreement with Janssen, on March 3, 2015, we announced an organizational resizing to reduce our workforce from 39 to 21 positions. For the three months ended March 31, 2015, we recognized $406,000 in restructuring charges for the pro-rata portion of the one-time termination benefits, which included $90,000 of non-cash stock-based compensation expense relating to the extension of the post-termination exercise period for certain stock options previously granted to employees affected by the restructuring from 90 days to one year from their respective termination dates. For the year ended December 31, 2015, we recorded aggregate restructuring charges of approximately $1,306,000 related to one-time termination benefits which were recognized on a pro-rata basis commencing from the date of announcement of the resizing over the specified remaining service periods for the employees affected by the restructuring. All actions associated with this restructuring were completed in 2015, and we do not anticipate incurring any further charges in connection with this restructuring. We expect this restructuring to result in aggregate cash expenditures of approximately $999,000, of which $964,000 has been paid as of March 31, 2016. The components relating to the restructuring, including the outstanding restructuring liability which is included in accrued restructuring charges on our condensed balance sheet as of March 31, 2016, are summarized in the following table: (In thousands) Employee Severance and Other Benefits Beginning accrual balance as of December 31, 2015 $ Cash payments ) Ending accrual balance as of March 31, 2016 $

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2016
COMMITMENTS AND CONTINGENCIES.
COMMITMENTS AND CONTINGENCIES	5. COMMITMENTS AND CONTINGENCIES Securities and Derivative Lawsuits On March 14, 2014, a purported class action securities lawsuit was commenced in the United States District Court for the Northern District of California, or the California District Court, naming as defendants us and certain of our officers. The lawsuit alleges violations of the Securities Exchange Act of 1934 in connection with allegedly false and misleading statements made by us related to our Phase 2 trial of imetelstat in patients with essential thrombocythemia, or ET, or polycythemia vera, or PV. The plaintiff alleges, among other things, that we failed to disclose facts related to the occurrence of persistent low-grade liver function test, or LFT, abnormalities observed in our Phase 2 trial of imetelstat in ET or PV patients and the potential risk of chronic liver injury following long-term exposure to imetelstat. The plaintiff seeks damages and an award of reasonable costs and expenses, including attorneys’ fees. On March 28, 2014, a second purported class action securities lawsuit was commenced in the California District Court, and on June 6, 2014, a third securities lawsuit, not styled as a class action, was commenced in the United States District Court for the Southern District of Mississippi, or the Mississippi District Court, naming as defendants us and certain of our officers. These lawsuits, which are based on the same factual background as the purported class action securities lawsuit that commenced on March 14, 2014, also allege violations of the Securities Exchange Act of 1934 and seek damages and an award of reasonable costs and expenses, including attorneys’ fees. On June 30, 2014, the California District Court consolidated both of the purported class action securities lawsuits filed in the California District Court, or the Class Action Lawsuits, and appointed a lead plaintiff and lead counsel to represent the purported class. On July 21, 2014, the California District Court ordered the lead plaintiff to file its consolidated amended complaint in the Class Action Lawsuits, which was filed on September 19, 2014. On August 11, 2014, we filed a motion to transfer the securities lawsuit filed in the Mississippi District Court to the California District Court. On November 4, 2014, the Mississippi District Court granted our motion and transferred the case to the California District Court, which was thereafter consolidated with the Class Action Lawsuits. We filed our motion to dismiss the consolidated amended complaint on November 18, 2014. On April 10, 2015, the California District Court granted our motion to dismiss with respect to some of the allegedly false and misleading statements made by us and denied our motion to dismiss with respect to other allegedly false and misleading statements made by us. On May 22, 2015, we filed our answer to the consolidated amended complaint in the Class Action Lawsuits. It is possible that additional suits will be filed, or allegations made by stockholders, with respect to these same or other matters and also naming us and/or our officers and directors as defendants. We believe we have meritorious defenses and intend to defend against these lawsuits vigorously. On April 21, 2014, a stockholder purporting to act on our behalf filed a derivative lawsuit in the Superior Court of California for the County of San Mateo, or the San Mateo County Court, against certain of our officers and directors. The lawsuit alleges breaches of fiduciary duties by the defendants and other violations of law. In general, the lawsuit alleges that the defendants caused or allowed the dissemination of allegedly false and misleading statements related to our Phase 2 trial of imetelstat in patients with ET or PV. The plaintiff is seeking unspecified monetary damages and other relief, including reforms and improvements to our corporate governance and internal procedures. On June 26, 2015 and June 29, 2015, respectively, two additional derivative lawsuits naming certain of our officers and directors as defendants were filed in the California District Court by stockholders purporting to act on our behalf. The two derivative cases filed in the California District Court were consolidated on August 1 7 , 2015. On August 25, 2015, an additional derivative lawsuit naming certain of our officers and directors as defendants was filed in the San Mateo County Court. The two derivative cases filed in the San Mateo County Court were consolidated on September 2 5, 2015. These lawsuits, each of which is based on the same factual background as the derivative lawsuit filed on April 21, 2014 in the San Mateo County Court, also allege breaches of fiduciary duties by the defendants and other violations of law. The plaintiffs in each of the foregoing derivative lawsuits are seeking unspecified monetary damages and other relief, including reforms and improvements to our corporate governance and internal procedures. It is possible that additional derivative lawsuits will be filed with respect to these same or other matters and also naming our officers and directors as defendants. Proceedings in the derivative lawsuits have been stayed. We intend to vigorously defend against the claims alleged and to seek dismissal of these lawsuits. These lawsuits and any other related lawsuits are subject to inherent uncertainties, and the actual defense and disposition costs will depend upon many unknown factors. The outcome of these lawsuits is necessarily uncertain. We could be forced to expend significant resources in the defense against these and any other related lawsuits and we may not prevail. We currently are not able to estimate the possible cost to us from these lawsuits, as they are currently at an early stage, and we cannot be certain how long it may take to resolve these lawsuits or the possible amount of any damages that we may be required to pay. Such amounts could be material to our financial statements even if we prevail in the defense against these lawsuits. We have not established any reserves for any potential liability relating to these lawsuits. It is possible that we could, in the future, incur judgments or enter into settlements of claims for monetary damages.

SUMMARY OF SIGNIFICANT ACCOUN11

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation	Basis of Presentation The terms “Geron”, the “Company”, “we” and “us” as used in this report refer to Geron Corporation. The accompanying unaudited condensed financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management of Geron, all adjustments (consisting only of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 or any other period. These financial statements and notes should be read in conjunction with the financial statements for each of the three years ended December 31, 2015, included in the Company’s Annual Report on Form 10-K. The accompanying condensed balance sheet as of December 31, 2015 has been derived from audited financial statements at that date.
Net Loss Per Share	Net Loss Per Share Basic net income (loss) per share is calculated by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the periods presented, without consideration for common stock equivalents. Diluted net income per share is calculated by adjusting the weighted-average number of shares of common stock outstanding for the dilutive effect of common stock equivalents outstanding for the periods presented, as determined using the treasury-stock method. Potential dilutive securities primarily consist of outstanding stock options, restricted stock awards, and warrants to purchase our common stock. Diluted net loss per share excludes common stock equivalents outstanding for the periods presented, as determined using the treasury-stock method, as their effect would be anti-dilutive, resulting in the same number of shares being used for the calculation of basic and diluted net loss per share. For all periods presented in the accompanying condensed statements of operations, the net loss applicable to common stockholders is equal to the reported net loss. Since we incurred a net loss for the three months ended March 31, 2016 and 2015, 3,593,074 and 4,122,123 common stock equivalents, respectively, related to outstanding stock options and restricted stock awards (as determined using the treasury-stock method at the estimated average market value) were excluded from the diluted net loss per share calculation as their effect would have been anti-dilutive . In addition, for the three months ended March 31, 2016 and 2015, 10,617,930 and 8,783,291 potentially dilutive securities, respectively, were excluded from the treasury-stock method and calculation of diluted net loss per share as their effect would have been anti-dilutive .
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires us to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On a regular basis, management evaluates these estimates and assumptions. Actual results could differ from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Cash Equivalents and Marketable Securities We consider all highly liquid investments with an original maturity of three months or less to be cash equivalents. We are subject to credit risk related to our cash equivalents and marketable securities. We place our cash and cash equivalents in money market funds, commercial paper, corporate notes and cash operating accounts. Our marketable securities include U.S. government-sponsored enterprise securities, commercial paper and corporate notes with original maturities ranging from four to 24 months. We classify our marketable securities as available-for-sale. We record available-for-sale securities at fair value with unrealized gains and losses reported in accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses are included in interest and other income and are derived using the specific identification method for determining the cost of securities sold and have been insignificant to date. Dividend and interest income are recognized when earned and included in interest and other income in our condensed statements of operations. We recognize a charge when the declines in the fair values below the amortized cost basis of our available-for-sale securities are judged to be other-than-temporary. We consider various factors in determining whether to recognize an other-than-temporary charge, including whether we intend to sell the security or whether it is more likely than not that we would be required to sell the security before recovery of the amortized cost basis. Declines in market value associated with credit losses judged as other-than-temporary result in a charge to interest and other income. Other-than-temporary charges not related to credit losses are included in accumulated other comprehensive income (loss) in stockholders’ equity. We have not recorded any other-than-temporary impairment charges on our available-for-sale securities for the three months ended March 31, 2016 and 2015. See Note 2 on Fair Value Measurements.
Revenue Recognition	Revenue Recognition We recognize revenue for each unit of accounting when all of the following criteria have been met: (a) persuasive evidence of an arrangement exists, (b) delivery has occurred or services have been rendered, (c) the seller’s price to the buyer is fixed or determinable, and (d) collectability is reasonably assured. Amounts received prior to satisfying these revenue recognition criteria are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as current deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as noncurrent deferred revenue. License and/or Collaboration Agreements In addition to the exclusive collaboration and license agreement, or Collaboration Agreement, that we entered into with Janssen Biotech, Inc., or Janssen, in November 2014 (which is more fully described in Note 3 on Collaboration and License Agreement), we have entered into several license or collaboration agreements with various oncology, diagnostics, research tools and biologics production companies. Economic terms in these agreements may include non-refundable license payments in cash or equity securities, option payments in cash or equity securities, cost reimbursements, cost-sharing arrangements, milestone payments, royalties on future sales of products, or any combination of these items. In applying the appropriate revenue recognition guidance related to these agreements, we first assess whether the arrangement contains multiple elements. In this evaluation, we consider: (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires us to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis, and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in our control. In assessing whether an item has standalone value, we consider factors such as the research, manufacturing and commercialization capabilities of the collaboration partner or licensee and the availability of the associated expertise in the general marketplace. In addition, we consider whether the collaboration partner or licensee can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. We then apply the applicable revenue recognition criteria noted above to each of the separate units of accounting in determining the appropriate period and pattern of recognition. We determine how to allocate arrangement consideration to identified units of accounting based on the selling price hierarchy provided under relevant accounting guidance. The estimated fair value of deliverables under the arrangement may be derived using a best estimate of selling price if vendor-specific-objective evidence and third-party evidence are not available. Upfront non-refundable signing, license or non-exclusive option fees are recognized as revenue: (i) when rights to use the intellectual property have been delivered, if the license has standalone value from the other deliverables to be provided under the agreement, or (ii) over the term of the agreement if we have continuing performance obligations, as the arrangement would be accounted for as a single unit of accounting. When payments are received in equity securities, we do not recognize any revenue unless such securities are determined to be realizable in cash. At the inception of an arrangement that includes milestone payments, we assess whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether: (i) the consideration is commensurate with either the performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the performance to achieve the milestone, (ii) the consideration relates solely to past performance and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. We consider various factors, such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone and the level of effort and investment required to achieve the respective milestone, in making this assessment. There is considerable judgment involved in determining whether a milestone satisfies all of the criteria required to conclude that a milestone is substantive. Milestone payments for milestones that are considered substantive would be recognized as revenue in their entirety upon successful accomplishment of the milestone, assuming all other revenue recognition criteria are met. Milestone payments for milestones that are not considered substantive would be recognized as revenue over the remaining period of performance, assuming all other revenue recognition criteria are met. Royalties are recognized as earned in accordance with contract terms when royalties from licensees can be reasonably estimated and collectability is reasonably assured. If royalties cannot be reasonably estimated or collectability of a royalty amount is not reasonably assured, royalties are recognized as revenue when the cash is received. Revenue from commercial milestone payments is accounted for as royalties and recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met. Cost-sharing expenses are recorded as earned or owed based on the performance requirements by both parties under the respective contracts. For arrangements in which we and our collaboration partner in the agreement are exposed to significant risks and rewards depending on the commercial success of the activity, we recognize payments between the parties on a net basis and record such amounts as a reduction or addition to research and development expense. For arrangements in which we have agreed to perform certain research and development services for our collaboration partner and are not exposed to significant risks and rewards depending on the commercial success of the activity, we recognize the respective cost reimbursements as revenue under the collaborative agreement as the related research and development services are rendered.
Restricted Cash	Restricted Cash Restricted cash consists of funds maintained in a separate certificate of deposit account for credit card purchases.
Research and Development Expenses	Research and Development Expenses Research and development expenses consist of expenses incurred in identifying, developing and testing product candidates resulting from our independent efforts as well as efforts associated with collaborations. These expenses include, but are not limited to, in-process research and development acquired in an asset acquisition and deemed to have no alternative future use, payroll and personnel expense, lab supplies, preclinical studies, clinical trials, including support for investigator-sponsored clinical trials, raw materials to manufacture clinical trial drugs, manufacturing costs for research and clinical trial materials, sponsored research at other labs, consulting, costs to maintain technology licenses, our proportionate share of research and development costs under cost-sharing arrangements with collaboration partners and research-related overhead. Research and development costs are expensed as incurred, including payments made under our collaboration and/or license agreements. For the clinical development activities being conducted by Janssen, we monitor patient enrollment levels and related activities to the extent possible through discussions with Janssen personnel and base our estimates on the best information available at the time. However, additional information may become available to us which would allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain.
Depreciation and Amortization	Depreciation and Amortization We record property and equipment at cost and calculate depreciation using the straight-line method over the estimated useful lives of the assets, generally four years. Leasehold improvements are amortized over the shorter of the estimated useful life or remaining term of the lease.
Stock-Based Compensation	Stock-Based Compensation We recognize stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting period. The following table summarizes the stock-based compensation expense included in operating expenses on our condensed statements of operations related to stock options, restricted stock awards and employee stock purchases for the three months ended March 31, 2016 and 2015 which was allocated as follows: Three Months Ended March 31, (In thousands) 2016 2015 Research and development $ $ Restructuring charges — General and administrative Stock-based compensation expense included in operating expenses $ $ In connection with a restructuring we announced in March 2015, the post-termination exercise period for certain stock options previously granted to employees affected by the restructuring was extended from 90 days to one year from their respective termination dates, subject to each employee’s continuous service until his/her specified termination date. The incremental value associated with these stock option modifications was recognized as non-cash stock-based compensation expense over each employee’s remaining service period with the Company and recorded as restructuring charges on our condensed statements of operations as reflected in the table above. See Note 4 on Restructuring for a further discussion of the March 2015 restructuring. As stock-based compensation expense recognized in our condensed statements of operations for the three months ended March 31, 2016 and 2015 is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures, but at a minimum, reflects the grant-date fair value of those awards that actually vested in the period. Forfeitures have been estimated at the time of grant based on historical data and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Stock Options We grant options with service-based vesting under our equity plans to employees, non-employee directors and consultants. The vesting period for employee options is generally four years. The fair value of options granted during the three months ended March 31, 2016 and 2015 has been estimated at the date of grant using the Black Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility 0.890 0.884 Risk-free interest rate 1.21% 1.70% Expected term 5.5 yrs 5.5 yrs Employee Stock Purchase Plan The fair value of employees’ purchase rights during the three months ended March 31, 2016 and 2015 has been estimated using the Black Scholes option-pricing model with the following assumptions: Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility range 0.684 0.721 to 1.392 Risk-free interest rate range 0.28% 0.11% to 0.25% Expected term range 12 mos 6 – 12 mos Dividend yield is based on historical cash dividend payments. The expected volatility is based on historical volatilities of our stock since traded options on Geron stock do not correspond to option terms and the trading volume of options is limited. The risk-free interest rate is based on the U.S. Zero Coupon Treasury Strip Yields for the expected term in effect on the date of grant for an award. The expected term of options is derived from actual historical exercise and post-vesting cancellation data and represents the period of time that options granted are expected to be outstanding. The expected term of employees’ purchase rights is equal to the purchase period. Restricted Stock Awards We have granted restricted stock awards to employees and non-employee directors with service-based vesting schedules that generally vest annually over four years. The fair value for service-based restricted stock awards is determined using the fair value of our common stock on the date of grant. The fair value is amortized as stock-based compensation expense over the requisite service period of the award, which is generally the vesting period, on a straight-line basis and is reduced for estimated forfeitures, as applicable. Non-Employee Stock-Based Awards For our non-employee stock-based awards, the measurement date on which the fair value of the stock-based award is calculated is equal to the earlier of: (i) the date at which a commitment for performance by the counterparty to earn the equity instrument is reached or (ii) the date at which the counterparty’s performance is complete. We recognize stock-based compensation expense for the fair value of the vested portion of non-employee awards in our condensed statements of operations.
Segment Information	Segment Information Our executive management team represents our chief decision maker. We view our operations as a single segment, the development of therapeutic products for oncology. As a result, the financial information disclosed herein materially represents all of the financial information related to our principal operating segment.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2014-09, or ASU 2014-09, which creates Accounting Standards Codification Topic 606, Revenue from Contracts with Customers , or Topic 606, and supersedes the revenue recognition requirements in Accounting Standards Codification Topic 605, Revenue Recognition , including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. In summary, the core principle of Topic 606 is to recognize revenue when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. Companies are allowed to select between two transition methods: (1) a full retrospective transition method with the application of the new guidance to each prior reporting period presented, or (2) a retrospective transition method that recognizes the cumulative effect on prior periods at the date of adoption together with additional footnote disclosures. The amendments in ASU 2014-09 are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period, and early application is not permitted. We are currently evaluating the impact that the adoption of ASU 2014-09 will have on our financial statements and related disclosures and have not made any decision on the method of adoption. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes , or ASU 2015-17. Current generally accepted accounting principles requires an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. To simplify the presentation of deferred income taxes, ASU 2015-17 requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets of a tax paying component of an entity be offset and presented as a single amount is not affected by the amendments in this update. The amendments in this update are effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Earlier application is permitted for all entities as of the beginning of an interim or annual reporting period. We are currently evaluating the impact that the adoption of ASU 2015-17 will have on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) , or ASU 2016-02. ASU 2016-02 requires an entity to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. Recognition, measurement and presentation of expenses will depend on classification as a finance or operating lease. Certain quantitative and qualitative disclosures about leasing arrangements also are required. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The updated guidance requires a modified retrospective adoption. We are currently evaluating the impact that the adoption of ASU 2016-02 will have on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting , or ASU 2016-09, which amends Accounting Standards Codification Topic 718, Compensation — Stock Compensation . ASU 2016-09 simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods and early adoption is permitted. We are currently evaluating the impact of the adoption of ASU 2016-09 on our financial statements and related disclosures and have not made any decision regarding the timing of adoption. With the exception of the standards discussed above, there have been no new accounting pronouncements not yet effective that have significance, or potential significance, to our financial statements.

SUMMARY OF SIGNIFICANT ACCOUN12

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Summary of allocation of stock-based compensation expense included in operating expenses on condensed statements of operations related to share-based payment awards	Three Months Ended March 31, (In thousands) 2016 2015 Research and development $ $ Restructuring charges — General and administrative Stock-based compensation expense included in operating expenses $ $
Schedule of assumptions used to estimate the fair value of stock options granted	Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility 0.890 0.884 Risk-free interest rate 1.21% 1.70% Expected term 5.5 yrs 5.5 yrs
Schedule of assumptions used to estimate the fair value of employee stock purchases under the purchase plan	Three Months Ended March 31, 2016 2015 Dividend yield 0% 0% Expected volatility range 0.684 0.721 to 1.392 Risk-free interest rate range 0.28% 0.11% to 0.25% Expected term range 12 mos 6 – 12 mos

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2016
FAIR VALUE MEASUREMENTS
Schedule of cash equivalents, restricted cash and marketable securities by security type	Cash equivalents, restricted cash and marketable securities by security type at March 31, 2016 were as follows: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Included in cash and cash equivalents: Money market funds $ $ — $ — $ Commercial paper — Corporate notes — — $ $ $ — $ Restricted cash: Certificate of deposit $ $ — $ — $ Marketable securities: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ $ ) $ Commercial paper (due in less than 1 year) ) Corporate notes (due in less than 1 year) ) Corporate notes (due in 1 to 2 years) ) $ $ $ ) $ Cash equivalents, restricted cash and marketable securities by security type at December 31, 2015 were as follows: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Included in cash and cash equivalents: Money market funds $ $ — $ — $ Government-sponsored enterprise securities — — Commercial paper — — Corporate notes — ) $ $ — $ ) $ Restricted cash: Certificate of deposit $ $ — $ — $ Marketable securities: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ — $ ) $ Commercial paper (due in less than 1 year) ) Corporate notes (due in less than 1 year) ) Corporate notes (due in 1 to 2 years) — ) $ $ $ ) $
Schedule of cash equivalents and marketable securities with unrealized losses	Less Than 12 Months 12 Months or Greater Total Gross Gross Gross Estimated Unrealized Estimated Unrealized Estimated Unrealized (In thousands) Fair Value Losses Fair Value Losses Fair Value Losses As of March 31, 2016: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ ) $ — $ — $ $ ) Commercial paper (due in less than 1 year) ) — — ) Corporate notes (due in less than 1 year) ) ) ) Corporate notes (due in 1 to 2 years) ) — — ) $ $ ) $ $ ) $ $ ) As of December 31, 2015: Government-sponsored enterprise securities (due in 1 to 2 years) $ $ ) $ — $ — $ $ ) Commercial paper (due in less than 1 year) ) — — ) Corporate notes (due in less than 1 year) ) ) ) Corporate notes (due in 1 to 2 years) ) — — ) $ $ ) $ $ ) $ $ )
Schedule of financial instruments measured at fair value on recurring basis	The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of March 31, 2016 and indicates the fair value category assigned. Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs (In thousands) Level 1 Level 2 Level 3 Total Money market funds (1) $ $ — $ — $ Government-sponsored enterprise securities (3) — — Commercial paper (1)(2) — — Corporate notes (1)(2)(3) — — Total $ $ $ — $ The following table presents information about our financial instruments that are measured at fair value on a recurring basis as of December 31, 2015 and indicates the fair value category assigned. Fair Value Measurements at Reporting Date Using Quoted Prices in Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs (In thousands) Level 1 Level 2 Level 3 Total Money market funds (1) $ $ — $ — $ Government-sponsored enterprise securities (1)(3) — — Commercial paper (1)(2) — — Corporate notes (1)(2)(3) — — Total $ $ $ — $ (1) Included in cash and cash equivalents on our condensed balance sheets. (2) Included in current portion of marketable securities on our condensed balance sheets. (3) Included in noncurrent portion of marketable securities on our condensed balance sheets.

RESTRUCTURING (Tables)

RESTRUCTURING (Tables)	3 Months Ended
	Mar. 31, 2016
RESTRUCTURING
Summary of components of restructuring liability	(In thousands) Employee Severance and Other Benefits Beginning accrual balance as of December 31, 2015 $ Cash payments ) Ending accrual balance as of March 31, 2016 $

SUMMARY OF SIGNIFICANT ACCOUN15

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ANTI-DILUTIVE SHARES (Details) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potential dilutive securities excluded from diluted earnings (loss) per share calculation (in shares)	10,617,930	8,783,291
Stock options and restricted stock awards excluded from diluted net loss per share calculation due to net loss position
Antidilutive Securities Excluded from Computation of Earnings Per Share
Potential dilutive securities excluded from diluted earnings (loss) per share calculation (in shares)	3,593,074	4,122,123

SUMMARY OF SIGNIFICANT ACCOUN16

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - MARKETABLE SECURITIES AND USEFUL LIVES OF ASSETS (Details)	3 Months Ended
	Mar. 31, 2016
Depreciation and Amortization
Estimated useful lives of assets	4 years
Minimum
Marketable securities
Original maturity period of marketable securities	4 months
Maximum
Marketable securities
Original maturity period of marketable securities	24 months

SUMMARY OF SIGNIFICANT ACCOUN17

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK BASED COMPENSATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 2,019	$ 2,013
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	332	622
Restructuring charges
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses		90
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense included in operating expenses	$ 1,687	$ 1,301

SUMMARY OF SIGNIFICANT ACCOUN18

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK OPTIONS AND EMLOYEE STOCK PURCHASE PLAN (Details)	Mar. 03, 2015	Mar. 31, 2016	Mar. 31, 2015
Stock-Based Compensation
Original exercise period for vested outstanding awards after termination	90 days
Modified exercise period for vested outstanding awards after termination	1 year
Stock options
Stock-Based Compensation
Vesting period of awards		4 years
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)		0.00%	0.00%
Expected volatility (as a percent)		89.00%	88.40%
Risk-free interest rate (as a percent)		1.21%	1.70%
Expected term		5 years 6 months	5 years 6 months
Employee Stock Purchase Plan
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)		0.00%	0.00%
Expected volatility (as a percent)		68.40%
Expected volatility range, minimum (as a percent)			72.10%
Expected volatility range, maximum (as a percent)			139.20%
Risk-free interest rate (as a percent)		0.28%
Risk-free interest rate range, minimum (as a percent)			0.11%
Risk-free interest rate range, maximum (as a percent)			0.25%
Expected term		12 months
Employee Stock Purchase Plan | Minimum
Assumptions used to estimate fair value of awards
Expected term			6 months
Employee Stock Purchase Plan | Maximum
Assumptions used to estimate fair value of awards
Expected term			12 months
Service-based restricted stock awards
Stock-Based Compensation
Vesting period of awards		4 years

FAIR VALUE MEASUREMENTS - SECUR

FAIR VALUE MEASUREMENTS - SECURITY TYPE (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Included in cash and cash equivalents
Amortized Cost	$ 10,546	$ 19,177
Gross Unrealized Gains	1
Gross Unrealized Losses		(1)
Estimated Fair Value	10,547	19,176
Restricted cash
Amortized Cost	267	267
Estimated Fair Value	267	267
Marketable securities
Amortized Cost	128,783	125,397
Gross Unrealized Gains	86	50
Gross Unrealized Losses	(47)	(262)
Estimated Fair Value	128,822	125,185
Money market funds
Included in cash and cash equivalents
Amortized Cost	3,798	4,577
Estimated Fair Value	3,798	4,577
Commercial paper
Included in cash and cash equivalents
Amortized Cost	3,497	7,599
Gross Unrealized Gains	1
Estimated Fair Value	3,498	7,599
Government-sponsored enterprise securities
Included in cash and cash equivalents
Amortized Cost		1,999
Estimated Fair Value		1,999
Corporate notes
Included in cash and cash equivalents
Amortized Cost	3,251	5,002
Gross Unrealized Losses		(1)
Estimated Fair Value	3,251	5,001
Certificate of deposit
Restricted cash
Amortized Cost	267	267
Estimated Fair Value	267	267
Government-sponsored enterprise securities (due in 1 to 2 years)
Marketable securities
Amortized Cost	17,021	10,007
Gross Unrealized Gains	1
Gross Unrealized Losses	(2)	(57)
Estimated Fair Value	17,020	9,950
Commercial paper (due in less than 1 year)
Marketable securities
Amortized Cost	34,605	27,661
Gross Unrealized Gains	58	49
Gross Unrealized Losses	(1)	(2)
Estimated Fair Value	34,662	27,708
Corporate notes (due in less than 1 year)
Marketable securities
Amortized Cost	62,186	64,892
Gross Unrealized Gains	15	1
Gross Unrealized Losses	(17)	(77)
Estimated Fair Value	62,184	64,816
Corporate notes (due in 1 to 2 years)
Marketable securities
Amortized Cost	14,971	22,837
Gross Unrealized Gains	12
Gross Unrealized Losses	(27)	(126)
Estimated Fair Value	$ 14,956	$ 22,711

FAIR VALUE MEASUREMENTS - SEC20

FAIR VALUE MEASUREMENTS - SECURITIES WITH UNREALIZED LOSSES (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	$ 44,089	$ 101,501
Less Than 12 Months - Gross Unrealized Losses	(46)	(256)
More Than 12 Months - Estimated Fair Value	3,398	6,301
More Than 12 Months - Gross Unrealized Losses	(1)	(7)
Total - Estimated Fair Value	47,487	107,802
Total - Gross Unrealized Losses	(47)	(263)
Government-sponsored enterprise securities (due in 1 to 2 years)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	5,002	9,950
Less Than 12 Months - Gross Unrealized Losses	(2)	(57)
Total - Estimated Fair Value	5,002	9,950
Total - Gross Unrealized Losses	(2)	(57)
Commercial paper (due in less than 1 year)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	4,967	7,834
Less Than 12 Months - Gross Unrealized Losses	(1)	(2)
Total - Estimated Fair Value	4,967	7,834
Total - Gross Unrealized Losses	(1)	(2)
Corporate notes (due in less than 1 year)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	25,533	61,006
Less Than 12 Months - Gross Unrealized Losses	(16)	(71)
More Than 12 Months - Estimated Fair Value	3,398	6,301
More Than 12 Months - Gross Unrealized Losses	(1)	(7)
Total - Estimated Fair Value	28,931	67,307
Total - Gross Unrealized Losses	(17)	(78)
Corporate notes (due in 1 to 2 years)
Marketable securities with unrealized losses
Less Than 12 Months - Estimated Fair Value	8,587	22,711
Less Than 12 Months - Gross Unrealized Losses	(27)	(126)
Total - Estimated Fair Value	8,587	22,711
Total - Gross Unrealized Losses	$ (27)	$ (126)

FAIR VALUE MEASUREMENTS - RECUR

FAIR VALUE MEASUREMENTS - RECURRING BASIS (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets
Total	$ 139,369	$ 144,361
Money market funds
Assets
Total	3,798	4,577
Government-sponsored enterprise securities
Assets
Total	17,020	11,949
Commercial paper
Assets
Total	38,160	35,307
Corporate notes
Assets
Total	80,391	92,528
Level 1
Assets
Total	3,798	4,577
Level 1 | Money market funds
Assets
Total	3,798	4,577
Level 2
Assets
Total	135,571	139,784
Level 2 | Government-sponsored enterprise securities
Assets
Total	17,020	11,949
Level 2 | Commercial paper
Assets
Total	38,160	35,307
Level 2 | Corporate notes
Assets
Total	$ 80,391	$ 92,528

COLLABORATION AND LICENSE AGR22

COLLABORATION AND LICENSE AGREEMENT (Details)	Dec. 15, 2014USD ($)item	Sep. 30, 2015USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
LICENSE AGREEMENTS
Collaboration revenue		$ 35,000,000
Accrued collaboration charges			$ 3,537,000	$ 2,328,000
License agreements | Janssen Biotech | Initial Period
LICENSE AGREEMENTS
Upfront payment received	$ 35,000,000
Number of agreed upon studies | item	2
Percentage of costs to be paid by Geron	50.00%
Percentage of costs to be paid by Janssen	50.00%
Notification period	24 months
License agreements | Janssen Biotech | U.S. Opt-In Rights exercised
LICENSE AGREEMENTS
Percentage of costs to be paid by Geron	20.00%
Percentage of costs to be paid by Janssen	80.00%
Continuation Election milestone payment	$ 65,000,000
Aggregate maximum total payments for development and regulatory milestones under collaboration agreement	470,000,000
Aggregate maximum total of payments for sales milestones under collaboration agreement	$ 350,000,000
Tiered royalties percentage, low end of the range	mid-teens
Tiered royalties percentage, high end of the range	low twenties
U.S. selling effort percentage	20.00%
License agreements | Janssen Biotech | U.S. Opt-In Rights not exercised
LICENSE AGREEMENTS
Continuation Election milestone payment	$ 65,000,000
Aggregate maximum total payments for development and regulatory milestones under collaboration agreement	415,000,000
Aggregate maximum total of payments for sales milestones under collaboration agreement	$ 350,000,000
Tiered royalties percentage, low end of the range	double-digit
Tiered royalties percentage, high end of the range	mid-teens
Full U.S. Rights fee	$ 70,000,000
License agreements | Janssen Biotech | Collaborative Arrangement IP Exclusively Licensed
LICENSE AGREEMENTS
Percentage of costs to be paid by Geron	50.00%
Percentage of costs to be paid by Janssen	50.00%

RESTRUCTURING - (Details)

RESTRUCTURING - (Details)	Mar. 03, 2015USD ($)position	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Mar. 31, 2016USD ($)
Restructuring
Number of positions before restructuring | position	39
Number of positions after restructuring | position	21
Restructuring charges			$ 406,000	$ 1,306,000
Non-cash stock-based compensation expense			$ 90,000
Original exercise period for vested outstanding awards after termination	90 days
Modified exercise period for vested outstanding awards after termination	1 year
Expected cash payments	$ 999,000
Outstanding Restructuring Liability
Accrual balance at the beginning of the period		$ 52,000
Cash payments		(17,000)			$ 964,000
Accrual balance at the end of the period		$ 35,000		$ 52,000	$ 35,000