Molecular Templates announces hold for phase 1 study

Molecular Templates has announced that the FDA has placed a partial hold on its phase 1 study for MT-0169 based on previously disclosed cardiac adverse events in two patients dosed at 50mcg/kg that triggered the dose reduction to 5mcg/kg last year. Since this reduction four patients have been dosed at 5mcg/ kg and three at 10mcg/kg with no cardiac adverse events having been noted.
Of the two patients who experienced cardiac adverse events, the first experienced asymptomatic grade 2 myocarditis, while the second experienced asymptomatic grade 3 cardiomyopathy.
Both patients had full recoveries after a few months and no grade 4 or 5 toxicities were observed at the higher dose level.
Under the FDA’s current partial hold, current study participants may continue to receive treatment but no new patients can be enrolled until the hold is lifted.
The drug was intended to treat patients with relapsed multiple myeloma, and following the study resuming after protocol amendments in January 2022, patients were then treated with MT-0169 at lower dose levels of either 5mcg/kg or 10mcg/kg.
The FDA has asked the company to provide narratives on the two patients who experienced cardiotoxicity at the higher dose level, as well as justification for the revised dosage and data evaluating the clinical benefit-to-risk ratio for the lower doses.
Roger Waltzman, MD, chief medical officer at Molecular Templates, commented: “Patient safety is our highest priority. The 5 and 10mcg/kg cohorts have been completed and we have not observed any cardiac adverse events or other serious adverse events at these lower doses. One patient dosed at 5mcg/kg is in a stringent complete response and is in his seventh month of therapy. We look forward to sharing these data with the FDA and are confident in the benefit-risk profile of MT-0169attheselowerdoses.Weare excited to see early signs of clinical benefit in this difficult-to-treat patient population.”