A week after ADC Therapeutics paused its Zynlonta trial to review seven deaths and five other respiratory events in patients who received the drug, the company has scrapped the study altogether following an FDA partial clinical hold.

The trial was testing the drug, combined with Roche’s Rituxan, in unfit or frail patients with previously untreated diffuse large B-cell lymphoma (DLBCL). Citing the “challenges of defining the addressable segment” of the difficult-to-treat population, ADC believes the benefit-risk profile “does not support” the continuation of the study, the company said in a release.

The call came after a meeting with the FDA, in which the agency slapped a partial hold on enrolling new patients in the trial. However, the agency said patients who are already on the drug and seeing clinical benefits can remain enrolled after reconsenting.

After those patients are treated, ADC will take steps to wrap up the trial.

Out of the 12 respiratory-related, treatment-emergent adverse events that deterred the study, 11 were previously concluded to be “unrelated” or unlikely to be related to Zynlonta treatment. All of the seven patients who passed away were at least 80 years of age with at least one “significant” comorbidity, ADC said at the time of the original pause.

“Our top priority is the safety of every patient who participates in our clinical trials,” CEO Ameet Mallik said at the time in a company statement.

Zynlonta was cleared in 2021 under the FDA’s accelerated pathway as a solo treatment for adults with relapsed or refractory DLBCL after two prior lines of therapy. It was the first single-agent CD19-targeted antibody-drug conjugate to win approval after it posted an overall response rate of 48.3% in a phase 2 trial and is the company’s only approved product.

Meanwhile, ADC in May disclosed plans to lay off 17% of its workforce, including contractors, in a “new corporate and capital allocation strategy” that includes scrapping investment in two preclinical cancer programs in favor of “the most advanced, lower risk value-generating programs.”

That news came as the company replaced CEO and co-founder Chris Martin with Novartis vet Mallik. The following month, ADC brought in another former Novartis exec, David Gilman, to lead business and strategy.

Source: fiercePharma.com