Tumor DNA clearance reaches 39% in novel immunomodulator and ADC combination

The investigational combination of pumitamig and elfetabart drozuntecan (elfe-D) demonstrated a manageable safety profile and encouraging early antitumor activity in patients with small cell lung cancer (SCLC), according to first clinical data from the ongoing Phase 1b/2 BNT324-01 trial presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer (WCLC).

Pumitamig is an investigational PD-L1 x VEGF-A bispecific antibody, while elfe-D is an investigational B7H3 antibody-drug conjugate. The study represents the first reported data evaluating a PD-(L)1 x VEGF bispecific antibody combined with an antibody-drug conjugate in lung cancer.

"The early activity observed with pumitamig plus elfetabart drozuntecan is encouraging, including responses across multiple lines of therapy in small cell lung cancer," said Adam Schoenfeld, M.D., Memorial Sloan Kettering Cancer Center, New York/NY presenting author of the study.

Together with the manageable safety profile, these findings support further clinical development of the combination."

Adam Schoenfeld, M.D., Memorial Sloan Kettering Cancer Center

BNT324-01 is an ongoing global Phase 1b/2 study evaluating the efficacy and safety of pumitamig plus elfe-D in advanced or metastatic SCLC and non-small cell lung cancer (NSCLC). The trial includes dose escalation and backfill followed by dose expansion to support optimal dose selection. The primary endpoints are objective response rate and safety.

As of June 2, 2026, 193 patients with SCLC or NSCLC had received the combination. No dose-limiting toxicities occurred during dose escalation. Treatment-related adverse events occurred in 75.6% of patients, including grade 3 or higher treatment-related adverse events in 23.3%. The most common treatment-related events were gastrointestinal or hematologic and were mostly grade 1 or 2.

Among 71 efficacy-evaluable patients with SCLC as of July 7, 2026, one patient achieved a complete response, 49 achieved partial responses and 16 had stable disease. The overall objective response rate across all doses was 70.4%, and the disease control rate was 93.0%.

Response rates varied by treatment line: 92.3% in first-line SCLC, 77.3% in second-line disease and 52.4% in patients treated in the third line or later. Among patients previously treated with DLL3-targeting agents, the objective response rate was 70.0%.

Circulating tumor DNA analyses also showed early molecular activity. Among evaluable patients, 96% had confirmed ctDNA reduction from baseline at cycle 3, day 1, and 39% achieved ctDNA clearance.

Investigators concluded that the combination showed a manageable safety profile with encouraging early efficacy in SCLC, supporting further clinical development. NSCLC data were described as immature in the abstract and will be reported separately.