ADC Therapeutics pauses enrollment to mid-stage trial for cancer drug

ADC Therapeutics pauses enrollment to mid-stage trial for cancer drug

July 11 (Reuters) – ADC Therapeutics (ADCT.N) has paused enrollments in a mid-stage study evaluating its drug Zynlonta for treating a type of blood cancer over safety concerns, it said on Tuesday, sending its shares down 16% in premarket trading.

The move comes after a review of data of 40 patients in the trial indicated potentially excessive respiratory-related events, including seven deaths and five serious adverse events.

An investigator assessment showed 11 of the 12 events, including six of the seven deaths, were individually assessed as unlikely or unrelated to study drug, the company said, adding that cause of the events are being further probed.

All patients with fatal events had one or more significant respiratory, cardiac co-morbidities and all were aged 80 years or above, ADC said.

The trial was testing Zynlonta along with rituximab, a biosimilar drug for Roche’s (ROG.S) monoclonal antibody Rituxan, in unfit or frail patients with previously untreated diffuse large B-cell lymphoma (DLBCL).

Zynlonta was granted an accelerated approval by the U.S. Food and Drug Administration for treating adults with certain types of large B-cell lymphoma that has come back or that did not respond to previous treatment.

A continued approval would require the drug to show clinical benefit in a confirmatory trial.

ADC said it has notified all study investigators and regulators, including in Europe, where the drug is approved, of its decision to pause enrollment.

It also does not expect to report more data from the trial by the end of the year.