CRISPR Therapeutics AG (NASDAQ:CRSP) was down $10.14 (14%) to $63.45 in after-hours trading after it said late Wednesday that FDA placed a clinical hold on its IND for a Phase I/II trial of CTX001 to treat sickle cell disease. CRISPR and partner Vertex Pharmaceuticals Inc. (NASDAQ:VRTX) said they expect additional information from the agency in the near future.
CRISPR said the hold does not affect its plans to start next half a European Phase I/II trial of CTX001 to treat transfusion-dependent beta-thalassemia.
Stocks for other companies developing CRISPR-associated protein 9 (Cas9)-based products also fell after hours Wednesday. Intellia Therapeutics Inc. (NASDAQ:NTLA) dropped $0.70 to $26 and Editas Medicine Inc. (NASDAQ:EDIT) fell $0.98 to $36.95.
CRISPR added $4.68 to $73.59 during trading hours Wednesday. Vertex added $1.40 to $156.64 during the session and was unchanged in after-hours trading.