Investment in Equity Securities	3 Months Ended
Mar. 31, 2022
Investments Debt And Equity Securities [Abstract]
Investment in Equity Securities	9. Investment in Equity Securities In November 2021, we entered into agreements related to the formation of SanReno, a corporation established to develop, manufacture and commercialize kidney disease therapies in mainland China, Hong Kong, Macau, Taiwan and Singapore (collectively, the “Territory”). In connection with the formation of SanReno and pursuant to a license agreement entered into between Chinook and SanReno in November 2021 (the “China License Agreement”), Chinook granted SanReno exclusive licenses under certain intellectual property to develop and commercialize atrasentan and BION-1301 in the Territory for use in all human indications. In return, Chinook received 40.0 million Series A preferred shares in SanReno representing 50% ownership of the outstanding voting securities and a warrant to purchase a total of 5.0 million common shares of SanReno at an exercise price of $0.01 per share upon the attainment of regulatory exclusivity for atrasentan in the Territory. Such warrant will only be exercisable if and provided that SanReno obtains, before the 10-year anniversary of the closing of the formation of SanReno, the regulatory exclusivity for atrasentan in China for at least three years commencing from the New Drug Application approval by the National Medical Product Administration of China. The warrant will have a five-year exercise period after it becomes exercisable upon satisfaction of the exercise conditions and was valued at $1.2 million on the grant date based on the probability of exercise of the warrant and the market for such instruments. An investor syndicate led by Frazier Healthcare Partners and Pivotal bioVenture Partners China, along with existing Chinook investors Versant Ventures and Samsara BioCapital, invested $40.0 million in exchange for an additional 40.0 million Series A preferred shares, representing the remaining 50% of the outstanding voting securities of SanReno. Refer to Note 11 “Collaboration and License Agreements” for more information regarding the China License Agreement. In connection with the formation of SanReno in November 2021, Chinook also entered into a Shareholders Agreement (the “Shareholders Agreement”) providing for certain rights and obligations of SanReno and its shareholders. Pursuant to the Shareholders Agreement, Chinook has the right to designate an individual for election to the board of directors of SanReno and SanReno has agreed that certain specified events (including certain liquidation events) shall require the approval of shareholders of SanReno holding a supermajority of SanReno’s Series A preferred shares. The Shareholders Agreement terminates by mutual consent of the parties, and automatically terminates upon the dissolution of SanReno or immediately prior to the consummation of a qualified initial public offering. We account for the investment in SanReno in accordance with the provisions of ASC Topic 321, Investments – Equity Securities, and elect to use the measurement alternative therein. As such, the investment is valued at $41.2 million as of March 31, 2022, which was the total of the aggregate cost value of the 40.0 million preferred shares in SanReno received by us on the date of the closing of the formation of SanReno and the grant date value of the warrant. The investment will be re-measured upon future observable price changes(s) in orderly transaction(s) or upon impairment, if any. There were no impairments of this investment during the three months ended March 31, 2022. Pursuant to the terms of the Series A preferred stock, we are entitled to non-cumulative dividends at 8% of our initial investment, payable when and if declared by the board of directors of SanReno. Dividends from our investment in equity securities, if declared, are reflected in the consolidated statements of operations and comprehensive loss. There were no dividends declared during the three months ended March 31, 2022.

Investment in Equity Securities

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

9. Investment in Equity Securities

In November 2021, we entered into agreements related to the formation of SanReno, a corporation established to develop, manufacture and commercialize kidney disease therapies in mainland China, Hong Kong, Macau, Taiwan and Singapore (collectively, the “Territory”). In connection with the formation of SanReno and pursuant to a license agreement entered into between Chinook and SanReno in November 2021 (the “China License Agreement”), Chinook granted SanReno exclusive licenses under certain intellectual property to develop and commercialize atrasentan and BION-1301 in the Territory for use in all human indications. In return, Chinook received 40.0 million Series A preferred shares in SanReno representing 50% ownership of the outstanding voting securities and a warrant to purchase a total of 5.0 million common shares of SanReno at an exercise price of $0.01 per share upon the attainment of regulatory exclusivity for atrasentan in the Territory. Such warrant will only be exercisable if and provided that SanReno obtains, before the 10-year anniversary of the closing of the formation of SanReno, the regulatory exclusivity for atrasentan in China for at least three years commencing from the New Drug Application approval by the National Medical Product Administration of China. The warrant will have a five-year exercise period after it becomes exercisable upon satisfaction of the exercise conditions and was valued at $1.2 million on the grant date based on the probability of exercise of the warrant and the market for such instruments. An investor syndicate led by Frazier Healthcare Partners and Pivotal bioVenture Partners China, along with existing Chinook investors Versant Ventures and Samsara BioCapital, invested $40.0 million in exchange for an additional 40.0 million Series A preferred shares, representing the remaining 50% of the outstanding voting securities of SanReno. Refer to Note 11 “Collaboration and License Agreements” for more information regarding the China License Agreement.

In connection with the formation of SanReno in November 2021, Chinook also entered into a Shareholders Agreement (the “Shareholders Agreement”) providing for certain rights and obligations of SanReno and its shareholders. Pursuant to the Shareholders Agreement, Chinook has the right to designate an individual for election to the board of directors of SanReno and SanReno has agreed that certain specified events (including certain liquidation events) shall require the approval of shareholders of SanReno holding a supermajority of SanReno’s Series A preferred shares. The Shareholders Agreement terminates by mutual consent of the parties, and automatically terminates upon the dissolution of SanReno or immediately prior to the consummation of a qualified initial public offering.

We account for the investment in SanReno in accordance with the provisions of ASC Topic 321, Investments – Equity Securities, and elect to use the measurement alternative therein. As such, the investment is valued at $41.2 million as of March 31, 2022, which was the total of the aggregate cost value of the 40.0 million preferred shares in SanReno received by us on the date of the closing of the formation of SanReno and the grant date value of the warrant. The investment will be re-measured upon future observable price changes(s) in orderly transaction(s) or upon impairment, if any. There were no impairments of this investment during the three months ended March 31, 2022.

Pursuant to the terms of the Series A preferred stock, we are entitled to non-cumulative dividends at 8% of our initial investment, payable when and if declared by the board of directors of SanReno. Dividends from our investment in equity securities, if declared, are reflected in the consolidated statements of operations and comprehensive loss. There were no dividends declared during the three months ended March 31, 2022.