Allogene Therapeutics, Inc. (NASDAQ:ALLO) shares dropped more than 45% on Friday following the U.S. Food and Drug Administration’s (FDA) halt on the company’s AlloCAR T clinical trials after the detection of AlloCAR cells with chromosomal abnormality in a single patient treated with ALLO-501A.

Rafael Amado, Executive Vice President of Research and Development and Chief Medical Officer of Allogene, said that they will work closely with the FDA to determine the next steps for advancing ALLO-501A. As the company investigates the issue, the analysts at Oppenheimer think that there will be delayed development timelines for key programs including ALLO-501A and ALLO-715, estimating the holds to range from 3 to 6 months.

Following this announcement, the analysts lowered their price target on the company’s shares to $40 from $44, while maintaining their outperform rating.