Subsequent Event	6 Months Ended
Jun. 30, 2022
Subsequent Events [Abstract]
Subsequent Event	13. Subsequent Events In July 2022, the Medicines and Healthcare products Regulatory Agency (MHRA) granted Great Britain marketing authorization for Oxbryta for the treatment of hemolytic anemia due to SCD in adult and pediatric patients 12 years of age and older as monotherapy or in combination with hydroxyurea. On August 7, 2022, we entered into an Agreement and Plan of Merger, or Merger Agreement, with Pfizer Inc., a Delaware corporation, or Pfizer, and Ribeye Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of Pfizer, or Merger Sub, pursuant to which, and upon the terms and subject to the conditions described therein, Merger Sub will merge with and into the Company, with the Company surviving the merger as a wholly owned subsidiary of Pfizer, which we refer to as the Merger. Under the Merger Agreement, at the closing of the Merger, each issued and outstanding share of our common stock (other than shares owned by the Company, any subsidiary of the Company, Pfizer, Merger Sub or any other subsidiary of Pfizer and other than stockholders of the Company who have validly exercised their statutory rights of appraisal under the DGCL) will be converted into the right to receive $68.50 per share, net to the seller in cash, without interest and subject to any required withholding of taxes. The Merger is expected to close as early as the fourth quarter of 2022. If the Merger Agreement is terminated under specified circumstances, we will be required to pay Pfizer a termination fee of $217 million. The Merger Agreement also provides that, in connection with the termination of the Merger Agreement under specified antitrust related circumstances, Pfizer will be required to pay us a “reverse termination fee” of $326 million.

Subsequent Event

6 Months Ended

Jun. 30, 2022

13. Subsequent Events

In July 2022, the Medicines and Healthcare products Regulatory Agency (MHRA) granted Great Britain marketing authorization for Oxbryta for the treatment of hemolytic anemia due to SCD in adult and pediatric patients 12 years of age and older as monotherapy or in combination with hydroxyurea.

On August 7, 2022, we entered into an Agreement and Plan of Merger, or Merger Agreement, with Pfizer Inc., a Delaware corporation, or Pfizer, and Ribeye Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of Pfizer, or Merger Sub, pursuant to which, and upon the terms and subject to the conditions described therein, Merger Sub will merge with and into the Company, with the Company surviving the merger as a wholly owned subsidiary of Pfizer, which we refer to as the Merger. Under the Merger Agreement, at the closing of the Merger, each issued and outstanding share of our common stock (other than shares owned by the Company, any subsidiary of the Company, Pfizer, Merger Sub or any other subsidiary of Pfizer and other than stockholders of the Company who have validly exercised their statutory rights of appraisal under the DGCL) will be converted into the right to receive $68.50 per share, net to the seller in cash, without interest and subject to any required withholding of taxes. The Merger is expected to close as early as the fourth quarter of 2022. If the Merger Agreement is terminated under specified circumstances, we will be required to pay Pfizer a termination fee of $217 million. The Merger Agreement also provides that, in connection with the termination of the Merger Agreement under specified antitrust related circumstances, Pfizer will be required to pay us a “reverse termination fee” of $326 million.