In a recent development, the US Food and Drug Administration (FDA) has placed an early-phase trial of 2seventy Bio’s groundbreaking CD33-targeted CAR-T cell therapy on hold. This decision comes after a tragic incident involving the death of a patient, which prompted the trial’s investigators to pause the study earlier this year.
The trial, previously halted in June, was a collaboration between Seattle Children’s and 2seventy Bio, aiming to explore the potential of the CD33-targeted CAR-T cell therapy. Named SC-DARIC33, this innovative therapy features a distinctive CAR architecture enabling physicians to activate and deactivate it using the drug rapamycin. This mechanism offers a degree of control over the therapy’s activity, showing promise for treating acute myeloid leukemia and potentially solid tumor targets.
The unfortunate patient’s passing led to a comprehensive internal investigation conducted by both 2seventy Bio and Seattle Children’s. The investigation aimed to uncover the cause of death and gain insights into the emerging underlying toxicity. This investigation resulted in significant changes to the study protocol, addressing the toxicity concerns and fostering optimism for the trial’s continuation.
However, despite these efforts, the FDA officially suspended the trial on August 11, signifying the necessity for further evaluation before proceeding. This decision underscores the FDA’s commitment to patient safety and thorough assessment of novel therapies.
2seventy Bio and Seattle Children’s remain committed to the trial’s success. They intend to collaborate closely with the FDA, providing a comprehensive root cause analysis alongside proposed modifications to the clinical study. This partnership between the biotech company and the hospital aims to expedite necessary changes and ensure the study resumes safely as soon as possible.
In a press release, 2seventy stated, “2seventy Bio and Seattle Children’s will continue to work with FDA to provide the root cause analysis and proposed changes for the clinical study. Based on upcoming discussions with FDA, 2seventy Bio and Seattle Children’s plan to amend the study accordingly and resume this study as soon as possible.”
The suspension of the clinical trial holds significance for 2seventy Bio, marking its first human testing of the drug-regulated CAR-T cell platform. Initial indications were positive, with the first dose level reportedly well-tolerated by the initial patient cohort.
Despite this setback, 2seventy Bio remains financially stable. The company concluded June with a robust financial position, boasting $307 million in cash and equivalents. This financial strength, coupled with revenue from the CAR-T therapy Abecma (a collaboration with Bristol Myers Squibb), assures 2seventy’s capacity to weather this temporary trial suspension and continue pioneering work well into 2026.
