In November 2019, we entered into a research collaboration and option agreement with KKC (the “2019 KKC Agreement”) for research associated with identifying two preclinical compounds that are ready for designation as development compounds (“DCs”), with one compound inhibiting the first undisclosed target (“Program 1”), and a second inhibiting the second undisclosed target (“Program 2”). Pursuant to the 2019 KKC Agreement, upon completion of the research and designation by the research steering committee of one or more DCs, KKC has the right to execute one or more separate collaborative agreements relating to the development and commercialization of one or both DCs in certain specified territories.

Under the terms of the 2019 KKC Agreement, KKC paid us a non-refundable, non-creditable upfront fee of $10.0 million in two installments as follows: the first installment of $5.0 million within 30 days of November 11, 2019 (the “Effective Date”), and the second installment of $5.0 million on the first anniversary of the Effective Date. The term of the 2019 KKC Agreement commenced on the Effective Date and ends on the earliest of: (i) 2 years following the Effective Date, (ii) the nomination of a program DC for both programs, (iii) the nomination of one program DC and the decision by the parties to cease research for the other program, or (iv) the decision by the parties to cease research for both programs.

We have no material future obligations under the 2019 KKC Agreement and recorded no revenue under the 2019 KKC Agreement during the three months ended March 31, 2022. During the three months ended March 31, 2021, we recognized $1.5 million as collaborative development revenue under the 2019 KKC Agreement in the accompanying condensed statement of operations and comprehensive loss.

In November 2017, we entered into an exclusive license agreement with KKC (the “2017 KKC Agreement”), for the development, commercialization, and distribution of tenapanor in Japan for cardiorenal indications. We granted KKC an exclusive license to develop and commercialize certain NHE3 inhibitors including tenapanor in Japan for the treatment of cardiorenal diseases and conditions, excluding cancer. We retained the rights to tenapanor outside of Japan, and also retained the rights to tenapanor in Japan for indications other than those stated above. Pursuant to the 2017 KKC Agreement, KKC is responsible for all costs and expenses incurred in the development and commercialization of tenapanor for all licensed indications in Japan. We are responsible for supplying the tenapanor drug substance for KKC’s use in development and commercialization throughout the term of the 2017 KKC Agreement, provided that KKC may exercise an option to manufacture the tenapanor drug substance under certain conditions.

We assessed these arrangements in accordance with Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606) and related amendments (“ASC 606”) and concluded that the contract counterparty, KKC, is a customer. Under the terms of the 2017 KKC Agreement, we received $30.0 million in upfront license fees, which was recognized as revenue when the agreement was executed. Based on our assessment, management determined that the license and the manufacturing supply services were its material performance obligations at the inception of the 2017 KKC Agreement, and as such, each of the performance obligations is distinct.

In addition to the up-front license fee received of $30.0 million, we may be entitled to receive up to $55.0 million in total development milestones, of which $10.0 million has been received and recognized as revenue as of March 31, 2022, and approximately ¥8.5 billion for commercialization milestones, or approximately $69.7 million at the currency exchange rate on March 31, 2022, as well as reimbursement of costs plus a reasonable overhead for the supply of product and royalties on net sales throughout the term of the agreement. The variable consideration related to the remaining development milestone payments has not been included in the transaction price as these were fully constrained at March 31, 2022.

As discussed in Note 14 - Subsequent events, on April 11, 2022, we entered into a second amendment (the "Amendment") to the 2017 KKC Agreement. Under the terms of the Amendment, the parties have agreed to a reduction in the royalty rate payable to us by KKC upon net sales of tenapanor in Japan. The royalty rate will be reduced from the high teens to low double digits for a two-year period of time following the first commercial sale in Japan, and then to mid-single digits for the remainder of the royalty term. As consideration for the reduction in the royalty rate, KKC has agreed to pay us up to an additional U.S. $40.0 million payable in two tranches, with the first payment due following KKC's filing with the Japanese Ministry Health, Labour and Welfare (MHLW) of its application for marketing approval for tenapanor and the second payment due following KKC’s receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan.

During the three months ended March 31, 2022 we recognized no licensing revenue upon the achievement of development milestones. During the three months ended March 31, 2021, we recognized $5.0 million licensing revenue upon the initiation of phase 3 clinical studies by KKC in Japan to evaluate tenapanor for hyperphosphatemia. During the three months ended March 31, 2022, we recognized $14 thousand as product supply revenue related to the manufacturing supply of tenapanor and other materials to KKC pursuant to the 2017 KKC Agreement. During the three months ended March 31, 2021, we recognized $0.1 million as product supply revenue pursuant to the 2017 KKC Agreement.

As detailed below under the heading Deferred revenue - non-current, we have received prepayments from KKC for the manufacturing of tenapanor drug substance that will be used to satisfy KKC needs. We also have recorded certain unbilled prepayments from KKC for the manufacturing of tenapanor drug product reflected within prepaid and other current assets. Both amounts are reflected within our deferred revenue, non-current on our condensed balance sheet as of March 31, 2022. The prepayment is reflected within prepaid and other current assets and deferred revenue, non-current on our condensed balance sheet as of March 31, 2022.

In December 2017, we entered into an exclusive license agreement with Fosun Pharma (the “Fosun Agreement”), for the development, commercialization and distribution of tenapanor in China for both hyperphosphatemia and IBS-C. We assessed these arrangements in accordance with ASC 606 and concluded that the contract counterparty, Fosun Pharma, is a customer. Under the terms of the Fosun Agreement, we received $12.0 million in upfront license fees which was recognized as revenue when the agreement was executed. Based on management’s assessment, we determined that the license and the manufacturing supply services represented the material performance obligations at the inception of the agreement, and as such, each of the performance obligations is distinct.

We may be entitled to additional development and commercialization milestones of up to $110.0 million, as well as reimbursement of cost plus a reasonable overhead for the supply of product and tiered royalties on net sales ranging from the mid-teens to 20%. The variable consideration related to the remaining development milestone payments has not been included in the transaction price as these were fully constrained at March 31, 2022.

In March 2018, we entered into an exclusive license agreement with Knight (the “Knight Agreement”) for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. We assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Knight, is a customer. Based on management’s assessment, we determined that the license and the manufacturing supply services represented the material performance obligations at the inception of the agreement, and as such, each of the performance obligations is distinct. Under the terms of the agreement, we received a $2.3 million nonrefundable, one-time upfront payment in March 2018 and are eligible to receive additional development and commercialization milestone payments worth up to $17.8 million. We are also eligible to receive royalties throughout the term of the agreement, and a transfer price for manufacturing services. The variable consideration related to the remaining development milestone payments has not been included in the transaction price as they were fully constrained at March 31, 2022.

In June 2015, we entered into a termination agreement with AstraZeneca (the “AstraZeneca Termination Agreement”) pursuant to which we have agreed to pay AstraZeneca (i) future royalties at a royalty rate of 10% of net sales of tenapanor or other NHE3 products by us or our licensees, and (ii) 20% of non-royalty revenue received from a licensee of tenapanor or another NHE3 inhibitor, up to a maximum of $75.0 million in aggregate for (i) and (ii). As of March 31, 2022, to date in aggregate, we have recognized $11.7 million of the $75.0 million, which has been recorded as cost of revenue, and have paid AstraZeneca $11.6 million. During the three months ended March 31, 2022 we recognized and recorded as cost of revenue $0.1 million related to the AstraZeneca Termination Agreement. During the three months ended March 31, 2021 we recognized $1.0 million cost of revenue related to the AstraZeneca Termination Agreement.

The following tables present changes in our current and non-current deferred revenue balances during the reporting period. The March 31, 2021 current deferred revenue balance is attributable entirely to the 2019 KKC Agreement and the non-current deferred revenue balances at March 31, 2022 and 2021 are attributable entirely to the 2017 KKC Agreement (in thousands):


Deferred revenue - non-current	2022		2021
Balance at January 1,	$	4,727	$	—

Increases to amounts invoiced, for which cash has not yet been received	3,829		2,947
Increase due to unbilled prepayments recorded during the period	7		—

Balance at March 31,	$	8,563	$	2,947