Collaboration and Licensing Agreements	6 Months Ended
Jun. 30, 2014
Collaboration and Licensing Agreements	4. Collaboration and Licensing agreements AstraZeneca AB (“AstraZeneca”) Under the terms of the AstraZeneca collaboration partnership agreement, the Company received an up-front license fee of $35.0 million in October 2012 and a $15.0 million payment in December 2013, which are both being recognized as revenue on a straight-line basis over the estimated period of performance, which is currently estimated to be December 2016. AstraZeneca reimburses the Company for its internal and external development-related costs. These reimbursements are recognized as collaborative development revenue when the development-related costs are incurred. In May 2014, the Company received from AstraZeneca a $25.0 million payment as a result of the dosing of the first patient in the Phase 2b clinical trial in hyperphosphatemia. As the $25.0 million did not meet the criteria to be considered the achievement of a substantive milestone for accounting purposes, the amount was recorded as deferred revenue when received and is being recognized as revenue on a straight-line basis over the remaining estimated period of performance under the AstraZeneca collaboration partnership agreement, which is currently estimated to be December 2016. As of June 30, 2014, the Company was eligible to receive future contingent payments up to a total of $795.0 million, which is comprised of future development milestones up to an additional $197.5 million and launch, commercialization, and sales milestones up to an additional $597.5 million. The contingent payments are triggered upon the activities expected to be undertaken by AstraZeneca. Revenue from milestones, if they are nonrefundable and deemed substantive, are recognized upon successful accomplishment of the milestone. The Company will recognize revenue associated with non-substantive milestones upon achievement of the milestones if there are no undelivered elements and it has no remaining performance obligation. To the extent that non-substantive milestones are achieved and the Company has remaining performance obligations, milestones are deferred and recognized as revenue over the estimated remaining period of performance. For the three months ended June 30, 2014 and 2013, the Company recognized revenue of $6.5 million and $2.0 million, respectively, related to amortization of the up-front and other license fees, and $2.6 million and $5.3 million for collaborative development services. For the six months ended June 30, 2014 and 2013, the Company recognized revenues of $9.7 million and $4.0 million, respectively, related to amortization of the up-front and other license fees, and $7.9 million and $9.9 million for collaborative development services. As of June 30, 2014 and December 31, 2013, the Company had total deferred revenue of $56.4 million and $40.3 million related to the AstraZeneca license agreement. Sanofi SA (“Sanofi”) In February 2014, the Company entered into a License Option and License Agreement with Sanofi (“Option and License Agreement”) for its NaP2b phosphate transport inhibitor program. NaP2b is an intestinal phosphate transporter whose activity accounts for a significant portion of dietary phosphate absorption in humans. The inhibition of NaP2b is believed to have utility for the treatment of hyperphosphatemia (elevated serum phosphate) in patients with end stage renal disease (ESRD) and other forms of chronic kidney disease (CKD). Under the Option and License Agreement, the Company granted Sanofi an exclusive worldwide license to conduct research utilizing the Company’s small molecule NaP2b inhibitors. In addition, Sanofi has the option to obtain an exclusive license to develop, manufacture and commercialize the Company’s NaP2b inhibitors. Sanofi is advancing this program towards first-in-human clinical trials. Under the Option and License Agreement, Sanofi is responsible for all of the costs and expenses for research and preclinical activities and, should it exercise its option, for the development and commercialization efforts under the program. Under the Option and License Agreement, the Company received a payment of $1.25 million, which was recognized as revenue after the Company provided to Sanofi the background know-how, listed patents, and materials (together, the “Technology Transfer Deliverables”) in May 2014 pursuant to the Option and License Agreement. The Company has the potential to earn future development, regulatory and commercial milestone payments of up to $196.8 million if Sanofi continues to advance the program into development and through commercialization. If a NaP2b inhibitor is commercialized by Sanofi as a result of this program, the Company will receive tiered royalties ranging from mid-single digits into the low double digits. As part of the arrangement with Sanofi, the Company retains an option to participate in co-promotional activities in the United States. Future potential milestone payments do not meet the criteria to be considered substantive milestones, and therefore will be treated as other contingent consideration and recognized as revenue as they are achieved as the Company has no performance obligations under the Option and License Agreement. No milestones have been received since the inception of the agreement.

4. Collaboration and Licensing agreements

AstraZeneca AB (“AstraZeneca”)

Under the terms of the AstraZeneca collaboration partnership agreement, the Company received an up-front license fee of $35.0 million in October 2012 and a $15.0 million payment in December 2013, which are both being recognized as revenue on a straight-line basis over the estimated period of performance, which is currently estimated to be December 2016. AstraZeneca reimburses the Company for its internal and external development-related costs. These reimbursements are recognized as collaborative development revenue when the development-related costs are incurred.

In May 2014, the Company received from AstraZeneca a $25.0 million payment as a result of the dosing of the first patient in the Phase 2b clinical trial in hyperphosphatemia. As the $25.0 million did not meet the criteria to be considered the achievement of a substantive milestone for accounting purposes, the amount was recorded as deferred revenue when received and is being recognized as revenue on a straight-line basis over the remaining estimated period of performance under the AstraZeneca collaboration partnership agreement, which is currently estimated to be December 2016.

As of June 30, 2014, the Company was eligible to receive future contingent payments up to a total of $795.0 million, which is comprised of future development milestones up to an additional $197.5 million and launch, commercialization, and sales milestones up to an additional $597.5 million. The contingent payments are triggered upon the activities expected to be undertaken by AstraZeneca. Revenue from milestones, if they are nonrefundable and deemed substantive, are recognized upon successful accomplishment of the milestone. The Company will recognize revenue associated with non-substantive milestones upon achievement of the milestones if there are no undelivered elements and it has no remaining performance obligation. To the extent that non-substantive milestones are achieved and the Company has remaining performance obligations, milestones are deferred and recognized as revenue over the estimated remaining period of performance.

For the three months ended June 30, 2014 and 2013, the Company recognized revenue of $6.5 million and $2.0 million, respectively, related to amortization of the up-front and other license fees, and $2.6 million and $5.3 million for collaborative development services. For the six months ended June 30, 2014 and 2013, the Company recognized revenues of $9.7 million and $4.0 million, respectively, related to amortization of the up-front and other license fees, and $7.9 million and $9.9 million for collaborative development services. As of June 30, 2014 and December 31, 2013, the Company had total deferred revenue of $56.4 million and $40.3 million related to the AstraZeneca license agreement.

Sanofi SA (“Sanofi”)

In February 2014, the Company entered into a License Option and License Agreement with Sanofi (“Option and License Agreement”) for its NaP2b phosphate transport inhibitor program. NaP2b is an intestinal phosphate transporter whose activity accounts for a significant portion of dietary phosphate absorption in humans. The inhibition of NaP2b is believed to have utility for the treatment of hyperphosphatemia (elevated serum phosphate) in patients with end stage renal disease (ESRD) and other forms of chronic kidney disease (CKD). Under the Option and License Agreement, the Company granted Sanofi an exclusive worldwide license to conduct research utilizing the Company’s small molecule NaP2b inhibitors. In addition, Sanofi has the option to obtain an exclusive license to develop, manufacture and commercialize the Company’s NaP2b inhibitors. Sanofi is advancing this program towards first-in-human clinical trials. Under the Option and License Agreement, Sanofi is responsible for all of the costs and expenses for research and preclinical activities and, should it exercise its option, for the development and commercialization efforts under the program. Under the Option and License Agreement, the Company received a payment of $1.25 million, which was recognized as revenue after the Company provided to Sanofi the background know-how, listed patents, and materials (together, the “Technology Transfer Deliverables”) in May 2014 pursuant to the Option and License Agreement.

The Company has the potential to earn future development, regulatory and commercial milestone payments of up to $196.8 million if Sanofi continues to advance the program into development and through commercialization. If a NaP2b inhibitor is commercialized by Sanofi as a result of this program, the Company will receive tiered royalties ranging from mid-single digits into the low double digits. As part of the arrangement with Sanofi, the Company retains an option to participate in co-promotional activities in the United States. Future potential milestone payments do not meet the criteria to be considered substantive milestones, and therefore will be treated as other contingent consideration and recognized as revenue as they are achieved as the Company has no performance obligations under the Option and License Agreement. No milestones have been received since the inception of the agreement.