In November 2019, we entered into a research collaboration and option agreement with KKC ("2019 KKC Agreement”), to undergo research to identify two preclinical study-ready compounds for designation as development compounds, 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 development candidates (“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 ("Effective Date"), and the second installment of $5.0 million on the first anniversary of the Effective Date. The original term of the 2019 KKC Agreement commenced on the Effective Date and was to end on the earliest of: (i) two 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 entered into three amendments to the 2019 KKC Agreement, which have resulted in the extension of the original term. Under the third amendment to the 2019 KKC Agreement entered into on June 28, 2022, the 2019 KKC Agreement ended on February 28, 2023.

We assessed the 2019 KKC Agreement in accordance with ASC 606 and concluded that the contract’s counterparty, KKC, is a customer. We also considered the modification guidance prescribed in ASC 606 and concluded that the 2019 KKC Agreement should be accounted for as a separate contract from the 2017 KKC Agreement, as defined and discussed below.

We identified various promises in the 2019 KKC Agreement, including the grant of an initial research license, the Program 1 research, the Program 2 research, the right to obtain certain development and commercialization rights with Program 1 in certain territories and the right to obtain development and commercialization rights with Program 2 in certain territories, and participation in a joint steering committee (“JSC”) and determined that KKC could not benefit from either of the research programs without the research license and participation in the JSC. As such, the combined license, research programs and participation in the JSC were deemed to be the highest level of goods and services that can be deemed distinct for each of the Program 1 research and Program 2 research. We concluded that the options to obtain additional development and commercialization rights that are exercisable by KKC under certain circumstances are not performance obligations of the contract at inception because the option fees reflect the standalone selling price of the options, and therefore, the options are not considered to be material rights.

At the outset of the 2019 KKC Agreement, we determined that the initial transaction price was $10.0 million and that revenue associated with the combined performance obligations should be recognized as services are provided using the input method. Since transfer of control occurs over time, in management’s judgment this input method is the best measure of progress towards satisfying the performance obligations and reflects a faithful depiction of the transfer of goods and services. Revenue was recognized over the Program 1 and Program 2 research periods which concluded in 2021.

During the years ended December 31, 2022 and 2021, we recognized zero and $4.2 million, respectively, as revenue under the 2019 KKC Agreement in the statement of operations and comprehensive loss. The transaction price had been fully allocated to revenue as of December 31, 2021 and there was no associated deferred revenue presented on the balance sheet as of December 31, 2022 or 2021. As of December 31, 2022 and 2021, we had no material future obligations under the 2019 KKC Agreement.

In November 2017, we entered into an exclusive license agreement with KKC (“2017 KKC Agreement”), under which 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. In October 2022, we entered into a Commercial Supply Agreement with KKC to further define the obligations of the parties with respect to the commercial supply of tenapanor drug substance (“2022 KKC Supply Agreement”). As detailed below under the heading “Deferred revenue’ we have received advanced payments from KKC for the manufacturing of tenapanor drug substance that will be used to satisfy KKC needs.

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 up-front license fees, which was recognized as revenue when the agreement was executed. Based on our assessment, management determined that the

Under the terms of the 2017 KKC Agreement, KKC paid us an up-front license fee of $30.0 million,. We may be entitled to receive up to $55.0 million in total development and regulatory milestones, of which $20.0 million has been received and recognized as revenue as of December 31, 2022. We may also be eligible to receive approximately ¥8.5 billion for commercialization milestones, or approximately $64.6 million at the currency exchange rate on December 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. As discussed in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, the future royalties and commercial milestone payments we may receive under the 2017 KKC Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement. The variable consideration related to the remaining milestone payments was fully constrained at December 31, 2022 and 2021.

In April 2022, we entered into a second amendment to the 2017 KKC Agreement ("2022 Amendment"). Under the terms of the 2022 Amendment, we and KKC have agreed to a reduction in the royalty rate payable to us by KKC upon net sales of tenapanor for hyperphosphatemia 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 discussed in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, the future commercial milestones and royalties we may receive under the 2017 KKC Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement. As consideration for the reduction in the royalty rate, KKC agreed to pay us up to an additional $40.0 million payable in two tranches, with the first payment due following KKC's filing with the Japanese Ministry of Health, Labour and Welfare 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.

In October 2022, we announced that KKC submitted an NDA to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis, which resulted in payment to us from KKC for an aggregate of $35.0 million for milestone payments and payments under the 2022 Amendment. We received these payments during the fourth quarter of 2022 and recorded them as licensing revenue on our statement of operations and comprehensive loss. The remaining variable consideration related to the reduction in the royalty rate was fully constrained at December 31, 2022. For the year ended December 31, 2021, $5.0 million of licensing revenue was recorded upon the initiation of phase 3 clinical studies by KKC in Japan to evaluate tenapanor for hyperphosphatemia.

For the years ended December 31, 2022 and 2021, $1.5 million and $0.9 million, respectively, of product supply revenue was recorded for manufacturing supply of tenapanor and other materials to KKC for product development and clinical trials in Japan, in accordance with our agreement with the 2017 KKC Agreement.

For the years ended December 31, 2022 and 2021, $35.0 million and $5.0 million, respectively, of licensing revenue was recorded. The 2022 licensing revenue was earned upon KKC's submission of an NDA to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. The 2021 licensing revenue was recorded upon the initiation of Phase 3 clinical studies by KKC in Japan to evaluate tenapanor for hyperphosphatemia.

In December 2017, we entered into an exclusive license agreement with Fosun Pharma ("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 up-front license fees which was recognized as revenue when the agreement was executed. Based on our 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 are 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 was fully constrained at December 31, 2022 and 2021.

In March 2018, we entered into an exclusive license agreement with Knight Therapeutics, Inc., ("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 our assessment, we determined that the license and the manufacturing supply services were the material performance obligations at the inception of the agreement and, as such, each of the performance obligations are distinct.

Under the terms of the Knight Agreement, we received a $2.3 million non-refundable, one-time upfront payment in March 2018 and may be eligible to receive additional development and commercialization milestone payments worth up to CAD22.2, or approximately $16.3 million at the currency exchange rate on December 31, 2022. We are also eligible to receive royalties ranging from the mid-single digits to the low twenties throughout the term of the agreement, and a transfer price for manufacturing services. The variable consideration related to the remaining development milestone payments were fully constrained at December 31, 2022 and 2021.

For the years ended December 31, 2022 and 2021, $31 thousand and $13 thousand of licensing revenue was recorded, respectively, related to the Knight Agreement. For the years ended December 31, 2022 and 2021, no product supply revenue was recorded, respectively, related to the Knight Agreement.

In June 2015, we entered into a termination agreement with AstraZeneca ("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 new collaboration partner should we elect to license, or otherwise provide rights to develop and commercialize tenapanor or another NHE3 inhibitor, up to a maximum of $75.0 million in aggregate for (i) and (ii). For the years ended December 31, 2022 and 2021, we recognized $3.6 million and $1.0 million, respectively, as cost of revenue related to the AstraZeneca Termination Agreement. To date in aggregate, we have recognized $15.3 million of the $75.0 million aggregate maximum 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 December 31, 2022 deferred revenue current and non-current balances are attributable entirely to prepayments for product supply under the 2017 KKC Agreement, while the December 31, 2021 current deferred revenue balance is attributable to the 2019 KKC Agreement and the December 31, 2021 non-current deferred revenue balance is attributable prepayments for product supply under the 2017 KKC Agreement (in thousands):


Deferred revenue - current	2022		2021
Balance at Balance at January 1,	$	—	$	4,177
Increases due to cash received, excluding amounts recognized as revenue during the period	42		—
Increases due to amounts reclassified from non-current, to be recognized in the next twelve months	3,961		—
Increases to amounts invoiced, for which cash has not yet been received	208		—

Decreases due to revenue recognized in the period for which cash has been received	—		(4,177)

Balance at December 31,	$	4,211	$	—