FDA places 2seventy CAR-T leukemia trial on clinical hold

Aug. 14, 2023

A few months after a patient’s death prompted 2seventy bio to voluntarily pause a phase 1 trial for its CAR T-cell therapy, the FDA officially placed the study on hold last Friday.

In June, the Massachusetts-based biotech announced a tragic Grade 5 serious adverse event resulting in a patient's death in its PLAT-08 study involving SC-DARIC33 for acute myeloid leukemia (AML). At the time, the study adhered to protocol-defined pausing rules while the events were assessed by regulatory and monitoring boards.

According to 2seventy's second quarter financial update, the FDA placed the study on hold via email on August 11. Since the pause, 2seventy bio and Seattle Children’s have been jointly conducting an internal investigation and root cause analysis of the event and have made changes in the study protocol aimed at mitigating the observed toxicity. Based on upcoming discussions with FDA, 2seventy bio and Seattle Children’s plan to amend the study accordingly and resume the study as soon as possible.

SC-DARIC33 is a novel CAR T-cell therapy that targets CD33 in investigational research. It harnesses 2seventy bio's special Dimerizing Agent Regulated Immunoreceptor Complex (DARIC) T-cell platform, a technology allowing controlled CAR T-cell activity through medication. This ongoing study is the first to explore the DARIC T-cell platform in humans.

AML, a rare and aggressive bone marrow cancer, has few treatment options. The therapy's premise is that a controlled CAR can effectively target AML while minimizing harm to normal myeloid and myeloid progenitor cells.