To me, what is intriguing about these data is the efficacy signal in the third-line setting, especially for the biomarker-positive patients, with a clinical benefit of 92%.

— Taofeek Kunle Owonikoko, MD

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Formal discussant Taofeek Kunle Owonikoko, MD, of Emory University School of Medicine, Atlanta, commented that this preliminary study looks promising for a new antibody-drug conjugate. “To me, what is intriguing about these data is the efficacy signal in the third-line setting, especially for the biomarker-positive patients, with a clinical benefit of 92%.”

He continued: “We think this approach has great promise. DLL3 [delta-like protein 3] is highly expressed in SCLC [small cell lung cancer]. I think the future depends on how well the investigators are able to further improve on the drug’s strengths and minimize the drug’s potential weaknesses. The convenient infusion schedule and activity seen in the third-line setting are really encouraging.”

Dr. Owonikoko viewed the treatment-emergent thrombocytopenia as a challenge to watch out for in patients with extensive bone involvement.

“Ongoing randomized trials are needed to confirm DLL3 as a biomarker and the cutoff of 50% or greater positive cells expression,” he noted. ■

Disclosure: Dr. Owonikoko is on the advisory board of Novartis, Genentech, AbbVie, Bayer, and Pfizer, and has received research support from BMS, AstraZeneca, Novartis, Celgene, Regeneron, G1 Therapeutics, AbbVie, Stemcentrx, and Takeda.