Poseida Therapeutics Inc.
shares dropped in the extended session Monday as the biotech drug maker announced a safety trial for a prostate cancer drug had been halted because of a patient death. Poseida shares, which closed the regular session down 0.8% at $13.00 and been halted on the news, dropped as much as 38% after hours, and were last down 32%. In a Securities and Exchange Commission filing, Poseida said the Food and Drug Administration paused the company’s Phase 1 trial for its prostate cancer treatment dubbed P-PSMA-101 to investigate the death of a patient enrolled in the study. The clinical investigator on the study said the death was “possibly” related to the treatment. Poseida launched its initial public offering in July with shares priced at $16 a piece.