The Food and Drug Administration has placed a hold on an early-stage clinical trial of a cell therapy for non-Hodgkin’s lymphoma, sending the developer’s shares downward.
Cambridge, Massachusetts-based Unum Therapeutics said Tuesday that the FDA had imposed the clinical hold on its Phase I ATTCK-20-2 study of ACTR087 and Roche’s Rituxan (rituximab) in relapsed or refractory B-cell NHL. The hold was due to a patient in the safety expansion cohort experiencing serious neurotoxicity and cytomegalovirus infection and life-threatening respiratory distress.
Shares of Unum fell more than 15 percent on the Nasdaq between Tuesday morning and late morning Wednesday, but they have recovered slightly since then.
Nevertheless, the company said in November 2018 that it was deprioritizing the ACTR087 program and would conclude enrollment in ATTCK-20-2 in the first half of 2019 in favor of another construct, ACTR707. That construct is currently in Phase I development in the same indication and is going into Phase I development for HER2-positive solid tumors. The ACTR platform, whose name stands for antibody-coupled T-cell receptor, involves a chimeric protein that binds to tumor-targeting antibodies, allowing ACTR T cells to be targeted against tumors through co-administration of cancer-specific monoclonal antibodies.
Notwithstanding the decision to deprioritize what was once the company’s lead program, this is not the first time ACTR087 has run into serious safety problems. When Unum filed to go public last March, it revealed that there were two patient deaths related to the ACTR087 construct in the ATTCK-20-2 study, in addition to another death that was deemed unrelated to the therapy, but followed an incident of severe cytokine release syndrome that was related to it. Those events also resulted in the FDA placing a hold on the trial, which was released in February 2018.
Still, while acknowledging that the clinical hold is not an issue due to ACTR087 being deprioritized, Cowen analyst Yaron Werber wrote in a note to investors Tuesday that the incident adds to concerns about the ACTR platform’s potential given what he called its lackluster efficacy. As such, ACTR707 data will be critical, he wrote.
According to preliminary Phase I data on ACTR707 presented at the American Society of Hematology meeting in December, four of nine patients treated at the first two dose levels achieved complete responses, and there had been no serious adverse events of cytokine release syndrome or neurotoxicity.
Photo: Streeter Lecka, Getty Images
