Our collaboration and license agreements typically involve us granting licenses of our intellectual property and performing research and development services in exchange of upfront fees, milestone payments and royalty payments. Since December 31, 2018, there have been no material changes to the key terms of our collaboration or license agreements. For further information on the terms and conditions of our existing collaboration and license agreements, please see the notes to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2018.

On January 1, 2018 we adopted ASC 606, Revenue from Contracts with Customers, under the modified retrospective method. Prior to January 1, 2018, we accounted for collaboration agreements under ASC 605-25, Multiple Element Arrangements. In determining the appropriate amount of revenue to be recognized under ASC 606, we performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measured the transaction price, including the constraint on variable consideration; (iv) allocated the transaction price to the performance obligations; and (v) recognized revenue when (or as) we satisfied each performance obligation.

For arrangements that include sales-based royalties and sales-based milestones and in which the license is deemed to be the predominant item to which the royalties relate, we recognize royalty revenue upon the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

At each reporting period we evaluate whether milestones are considered probable of being reached and, to the extent that a significant reversal would not occur in future periods, estimate the amount to be included in the transaction price using the most likely amount method. Milestone payments that are not within our control, such as regulatory approvals, are not considered probable of being achieved and are excluded from the transaction price until those approvals are received.

•In April 2010, we entered into a discovery and development collaboration and license agreement focused on cancer metabolism, or the 2010 Agreement, which was amended in October 2011 and July 2014. The discovery phase of the 2010 Agreement expired in April 2016. On August 15, 2016, we terminated the 2010 Agreement as to the program directed to the isocitrate dehydrogenase 1, or IDH1, target, for which ivosidenib was the lead development candidate. Accordingly, the sole program remaining under the 2010 Agreement is IDHIFA® (enasidenib), a co-commercialized licensed program for which Celgene leads and funds global development and commercialization activities. Under the remaining terms of the 2010 Agreement, we are eligible to receive up to $80.0 million in potential milestone payments for the enasidenib program. The potential milestone payments are comprised of: (i) up to $55.0 million in milestone payments upon achievement of specified ex-U.S. regulatory milestone events, and (ii) a $25.0 million milestone payment upon achievement of a specified ex-U.S. commercial milestone event, as well as royalties at tiered, low-double digit to mid-teen percentage rates on net sales of IDHIFA®.

•In April 2015, we entered into a joint worldwide development and profit share collaboration and license agreement with Celgene, and our wholly owned subsidiary, Agios International Sarl, entered into a collaboration and license agreement with Celgene International II Sarl, or collectively, the AG-881 Agreements, to establish a worldwide collaboration focused on the development and commercialization of vorasidenib products. Under the AG-881 Agreements, we and Celgene split all worldwide development costs for vorasidenib, subject to specified exceptions. The AG-881 Agreements were terminated effective September 4, 2018, upon which we received sole global rights to vorasidenib. In connection with the termination of the AG-881 Agreements, Celgene will be eligible to receive royalties from us at a low single-digit percentage rate on worldwide net sales of products containing vorasidenib.

•In May 2016, we entered into a master research and collaboration agreement with Celgene, or the 2016 Agreement, focused on metabolic immuno-oncology, or MIO. The initial four-year research term of the 2016 Agreement may be extended for up to two, or in specified cases, up to four additional one-year terms by paying a $40.0 million per year extension fee. Celgene has designated AG-270, our methionine adenosyltransferase 2a, or MAT2A, inhibitor, as a development candidate under the 2016 Agreement, and has the option, upon payment of an option exercise fee of at least $30.0 million, to participate in a worldwide 50/50 cost and profit share with us for AG-270, under which we are eligible for up to $168.8 million in potential milestone payments for the program, comprised of: (i) a $20.0 million milestone-based payment upon achievement of a specified clinical development event and (ii) up to $148.8 million in milestone-based payments upon achievement of specified regulatory milestone events. We are also eligible to receive designation, option exercise and milestone and royalty payments for other programs that may be designated for further development under the 2016 Agreement.


	Three Months Ended September 30,						Nine Months Ended September 30,
	2019		2018		2019		2018
Services performed that were considered performance obligations as of the modification dates
Licenses	$	—	$	—	$	—	$	15,000
On-going research and development services	4,695		7,504		29,915		23,698

Services performed that were not considered performance obligations as of the modification dates
Development activities	—		312		—		902
Commercialization activities	821		916		2,499		2,878
Total collaboration revenue - related party	$	5,516	$	8,732	$	32,414	$	42,478


	December 31, 2018		Additions		Deductions		September 30, 2019
Contract assets (1)
Collaboration receivable – related party	$	2,462	$	6,568	$	(7,192)	$	1,838
Royalty receivable – related party	2,234		7,569		(7,203)		2,600
Contract liabilities (2)
Deferred revenue – related party, current and net of current portions	92,519		5,000		(30,849)		66,670


	Three Months Ended September 30,						Nine Months Ended September 30,
	2019		2018		2019		2018
Amounts included in the contract liability at the beginning of the period	$	4,404	$	7,555	$	28,823	$	23,472
Performance obligations satisfied in previous periods	—		219		—		762

As of September 30, 2019, the aggregate amount of the transaction price allocated to performance obligations that are partially unsatisfied was $70.8 million. This amount is expected to be recognized as performance obligations are satisfied through March 2023.

As the underlying performance obligation, or delivery of the enasidenib license, had been satisfied as of June 2014, royalty revenue is recognized as the related sales occur. During the three and nine months ended September 30, 2019 and 2018, we recognized the following as royalty revenue (in thousands):

refractory, or R/R, acute myeloid leukemia, or AML. As a result of the filing, we recognized a $15.0 million milestone payment as collaboration revenue - related party. No other milestones were achieved during the three and nine months ended September 30, 2019 or 2018. The next potential milestone expected to be achieved under our Collaboration Agreements is the first regulatory approval in any of China, Japan or a major European country, which would result in a milestone payment of $35.0 million under the 2010 Agreement.

In June 2018, we and CStone Pharmaceuticals, or CStone, entered into an exclusive license agreement, or the CStone Agreement, to grant CStone specified intellectual property licenses to enable CStone to develop and commercialize certain products containing ivosidenib in mainland China, Hong Kong, Macau and Taiwan, or the CStone Territory. We retain development and commercialization rights for the rest of the world. Pursuant to the CStone Agreement, CStone will initially be responsible for the development and commercialization of ivosidenib in AML, cholangiocarcinoma, and, at our discretion, brain cancer indications. CStone is responsible for all costs it incurs in developing, obtaining regulatory approval of, and commercializing ivosidenib in the CStone Territory, as well as certain costs incurred by us. Pursuant to the CStone Agreement, we received an initial upfront payment in the amount of $12.0 million and are entitled to receive up to an additional $412.0 million in milestone payments upon the achievement of certain development, regulatory and sales milestone events. We will also be entitled to receive tiered royalties, ranging from 15% to 19% percent, on annual net sales, if any, of ivosidenib in the CStone Territory.


	Three Months Ended September 30,						Nine Months Ended September 30,
	2019		2018		2019		2018
Services performed that were considered performance obligations as of the inception date
License and other services	$	(103)	$	—	$	(103)	$	12,440
Services performed that were not considered performance obligations as of the inception date
Other Services	523		—		2,305		—

Total collaboration revenue - other	$	420	$	—	$	2,202	$	12,440

The license was determined to be the predominant item to which sales-based royalties and sales-based milestones relate. As the license was delivered in June 2018, we will recognize royalty revenue when the related sales occur. To date, no royalties have been received under the CStone Agreement.

No milestones were earned during the three and nine months ended September 30, 2019 and 2018. The next potential milestone expected to be achieved under the CStone Agreement is the dosing of the first patient in a local study in a hematological indication in mainland China. Achievement of this event will result in a milestone payment of $5.0 million.