In these initial studies, vadastuximab appears to be at least as good as, and maybe better than, gemtuzumab ozogamicin. It is certainly a route for bringing an anti-CD33 monoclonal antibody back to market in AML.

— Mikkael A. Sekeres, MD, MS

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Mikkael A. Sekeres, MD, MS, Director of the Leukemia Program at the Cleveland Clinic Taussig Cancer Center in Ohio, commented on vadastuximab talirine in newly diagnosed acute myeloid leukemia (AML). He noted that the drug is similar to gemtuzumab ozogamicin, another antibody-drug conjugate that was approved on the basis of phase II data but withdrawn in 2010 when a phase III trial failed to confirm efficacy; it was also linked to patient deaths.

“In these initial studies, vadastuximab appears to be at least as good as, and maybe better than, gemtuzumab ozogamicin. It is certainly a route for bringing an anti-CD33 monoclonal antibody back to market in AML,” Dr. Sekeres said. “It also may be better than other drugs we use to treat AML, based on studies showing benefit when added to standard therapy.”

However, he acknowledged that for approval, the hurdle may be high, based on past experience with gemtuzumab ozogamicin. “I would speculate that the U.S. Food and Drug Administration (FDA) would require a phase III trial or large randomized phase II data for approval of this drug,” he indicated. “The minimal residual disease–negative rates look good, and the FDA is, in fact, open to looking at minimal residual disease as an interim marker of clinically meaningful benefit.” ■

Disclosure: Dr. Sekeres reported no potential conflicts of interest.