The first reported data for pumitamig plus elfetabart drozuntecan (elfe-D) demonstrated a 70.4% objective response rate (ORR) in patients with small cell lung cancer (SCLC).

These findings were presented at the 2026 World Conference on Lung Cancer (WCLC) during the session titled The Breakthrough Immunotherapy for Advanced NSCLC.

The Breakthrough Immunotherapy for Advanced NSCLC

Pumitamig (PD-L1 x VEGF-A bsAb) + Elfetabart Drozuntecan (Elfe-D, B7H3 ADC) in Patients with Advanced/Metastatic Lung Cancer (NSCLC or SCLC)

Registered WCLC 2026 attendees can watch Dr. Schoenfeld and other presenters explore emerging combination strategies in NSCLC with on-demand access to session recordings via the virtual platform. WATCH NOW

Pumitamig is a bispecific antibody that targets PD-L1 and VEGF-A in the tumor and the tumor microenvironment (TME). Elfe-D—an antibody-drug conjugate (ADC)—targets B7H3 with a topoisomerase I inhibitor payload, a cleavable linker, and a drug-to-antibody ratio (DAR) of approximately 6. In preclinical models, the combination of pumitamig and elfe-D resulted in more durable tumor regression and improved tumor control, with significantly lower tumor volumes compared to monotherapy.

BNT324-01 is an ongoing global phase Ib/II study evaluating pumitamig in combination with elfe-D in advanced/metastatic SCLC and non-small cell lung cancer (NSCLC). Part one of the study included six dose levels; however, the two highest dose levels were ultimately deemed unnecessary due to early efficacy signals. Part two includes multiple cohorts in SCLC and NSCLC to support signal seeking and dose optimization.

As of July 7, 2026, a total of 279 patients had enrolled in the trial, including 201 with NSCLC and 78 with SCLC. The current analysis included 71 patients with SCLC who were evaluable for efficacy.

“The combination treatment showed encouraging early efficacy in SCLC across lines of therapy and dose levels, with a response rate of 70.4% overall, 92.3% in the frontline, 76.2% in the second line, and 52.4% in the third line, plus an 88% response rate among patients with prior delta-like ligand 3 (DLL3) T-cell engagers, all of which are still on treatment,” said Adam Schoenfeld, MD, a thoracic medical oncologist and translational researcher at Memorial Sloan Kettering Cancer Center.

Efficacy signals were observed regardless of patients’ smoking status or history of brain metastasis, with response rates of 73% among patients with a current or former smoking history, 60% among those who had never smoked, 71% among patients with brain metastases, and 70% among those without a history of brain metastases.

In addition to the radiologic response, 96% of evaluable patients achieved a substantial reduction in ctDNA.

Pumitamig plus elfe-D demonstrated a manageable safety profile. While 82% of patients experienced treatment-related adverse events (TRAEs), these were mostly grade 1 or 2 gastrointestinal or hematological events that were largely reversible with supportive measures. TRAEs leading to discontinuation of both drugs were low, occurring in less than 4% of patients, and TRAEs resulting in dose reduction of elfe-D occurred in 8.6% of patients.

For AEs of special interest, treatment-related proteinuria was observed in 6.1% of patients, while interstitial lung disease (ILD) or pneumonitis occurred in fewer than 3%. Deaths assessed by the investigator as possibly related to treatment were reported in two cases, one involving cardiac failure and the other due to pulmonary hemorrhage.

“There have been no significant early safety signals or safety signals that preclude further investigation, and the combination has been largely tolerable to date,” Dr. Schoenfeld said.