ADC Therapeutics is voluntarily pausing enrollment in a phase 2 study evaluating two drugs for lymphoma after seven patients died and five experienced worsening health during treatment.
The Switzerland-based drugmaker said July 11 it is investigating the cause of the events, according to a news release.
The trial is studying Zynlonta (loncastuximab tesirine-lpyl), an FDA-approved drug for some adults with large B-cell lymphoma, and rituximab (Lonca-R), as a possible therapy for diffuse large B-cell lymphoma.
Six of the seven deaths and the five respiratory-related treatment-emergent adverse events "were individually assessed as unlikely or unrelated to study drug," ADC Therapeutics said. Four of the five nonfatal adverse events have resolved and those patients completed their treatment regimen, the company said.
The study focused on unfit or frail patients with previously untreated diffuse large B-cell lymphoma. Among the six deaths, three patients were unfit and three were frail.
"All patients with fatal events had one or more significant active underlying respiratory and/or cardiac co-morbidities," the drugmaker said, "including severe chronic obstructive pulmonary disease, pulmonary edema, chronic bronchiectasis, idiopathic pulmonary fibrosis and recent COVID-19 infection and all were greater than or equal to 80 years of age."
"It is important to note," ADC added, that these 12 patients "would have been excluded from the LOTIS-5 [phase 3] trial."
The FDA and European Medicines Agency have been notified, and ADC does not expect to share additional data by the end of 2023, the release said.