License and collaboration agreements may contain multiple elements as evaluated under Accounting Standards Codification (ASC) 605-25, Revenue Recognition—Multiple-Element Arrangements, including agreements to provide research and development services, and manufacturing and commercialization services, grants of licenses to intellectual property rights and know-how, as well as participation in development and/or commercialization committees. Each deliverable under the agreement is evaluated to determine whether it qualifies as a separate unit of accounting based on whether the deliverable has standalone value to the customer. The arrangement’s consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the following hierarchy: (i) vendor-specific objective evidence of the fair value of the deliverable, if it exists; (ii) third-party evidence of selling price, if vendor-specific objective evidence is not available or (iii) the best estimate of selling price if neither vendor-specific objective evidence or third-party evidence is available.
Upfront payments for licenses are evaluated to determine if the licensee can obtain standalone value from the license separate from the value of the research and development services and other deliverables in the arrangement to be provided by us. The assessment of multiple-element arrangements also requires judgment in order to determine the allocation of revenue to each deliverable and the appropriate period of time over which the revenue should be recognized. If we determine that the license does not have standalone value separate from the research and development services, the license and the services are combined as one unit of accounting and upfront payments are recorded initially as deferred revenue in the balance sheet. Revenue is then recognized on a straight-line basis over an estimated performance period that is consistent with the term of performance obligations, unless the Company determines there is a discernible pattern of performance other than straight-line, in which case the Company uses a proportionate performance method to recognize the revenue over the estimated performance period. If the license is determined to have standalone value, then the allocated consideration is recorded as revenue when the license or is delivered.
License and collaboration agreements may also contain milestone payments that become due upon the achievement of certain milestones. We apply ASC 605-28, Revenue Recognition—Milestone Method. Under the milestone method, payments that are contingent upon achievement of a substantive milestone are recognized in the period in which the milestone is achieved. A substantive milestone is defined as an event that can only be achieved based on our performance, and there is substantive uncertainty about whether the event will be achieved at the inception of the arrangement. Events that are contingent only on the passage of time or only on counterparty performance are not considered milestones subject to this guidance. Further, for the milestone to be considered substantive, the amounts received must relate solely to prior performance, be reasonable relative to all of the deliverables and payment terms within the agreement, and commensurate with our performance to achieve the milestone.
Preclinical Study and Clinical Trial Accruals
Our preclinical study and clinical trial accruals are a component of research and development expenses, and based on patient enrollment and related costs at clinical investigator sites as well as estimates for the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage preclinical studies and clinical trials on our behalf.
We estimate preclinical study and clinical trial expenses based on the services performed, pursuant to contracts with research institutions and CROs that conduct and manage preclinical studies and clinical trials on our behalf. We estimate these expenses based on discussions with internal clinical management personnel and external service providers as to the progress or stage of completion of trials or services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, we will adjust the accrual accordingly. To date, there have been no material differences from our accrued preclinical study and clinical trial expenses to our actual preclinical and clinical expenses. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.
Stock-Based Compensation Expense
We account for stock-based compensation arrangements with employees in accordance with ASC 718, Stock Compensation. ASC 718 requires the recognition of compensation expense, using a fair value-based method, for costs related to all stock-based payments including stock options. Our determination of the fair value of stock options on the date of grant utilizes the Black-Scholes option-pricing model for stock options with time-based vesting, and is impacted by our common stock price as well as changes in assumptions regarding a number of highly complex and subjective variables. These variables include expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends.
The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. As permitted under ASU 2016-09, beginning January 1, 2017, we have elected to recognize forfeitures as they occur, and no longer estimate a forfeiture rate when calculating the stock-based compensation for our equity awards. Until December 31, 2016, stock-based compensation expense recognized at fair value included the impact of estimated forfeitures as we estimated future forfeitures at the date of grant and revised the estimates, if necessary, in subsequent periods if actual forfeitures differed from those estimates.