Study of Novel Drug Combo in Head and Neck Cancer Closed After Several Patient Deaths

MacroGenics Inc. recently announced that it discontinued a phase 2 trial investigating the safety and efficacy of a cancer treatment regimen consisting of enoblituzumab in combination with either retifanlimab or tebotelimab.

The regimen was being investigated as a first-line treatment option in patients with recurrent or metastatic squamous cell carcinoma of the head and neck.

The company announced that it stopped the trial after conducting an internal review of the safety data. Of the 62 patients treated in the study, seven died while enrolled on the trial. The deaths, according to a news release from MacroGenics may have been linked to hemorrhagic events, which is the loss of blood from a damaged blood vessel. These events, according to information from the Cleveland Clinic, can be minor or major. Some of the major events — such as bleeding in the brain — may lead to the occurrence of a stroke.

Investigators assessed the deaths and attributed six of the seven to be associated with disease progression or unrelated to any of the study drugs. However, the investigators determined that one death may have been possibly related to study treatment.

The number of deaths reported in the trial were higher than what has been previously reported in additional studies of this patient population, according to the release. The manufacturer noted that it informed the Food and Drug Administration of its decision and told investigators to discontinue enrolling any new patients onto the trial. The investigators, according to the release, were also told to stop any further treatment using the study regimen on patients already enrolled on the trial.

“Our top concern in conducting clinical trials is the safety of study participants,” Dr. Scott Koenig, president and CEO of MacroGenics, said in the release. “We were surprised by the emergence of these events in first-line (squamous cell carcinoma of the head and neck) patients, as we had not observed any such events in an earlier, smaller study in patients with later-line (squamous cell carcinoma of the head and neck) disease who were treated with enoblituzumab in combination with an anti-PD-1 antibody. Similar safety events have not been reported in patients treated with MGC018, our B7-H3-targeted ADC molecule, and the decision to close (this) study does not impact our ongoing MGC018 study activities.”

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