Pumitamig Shows 70% Response in Advanced Lung Cancer Regardless of PD-L1 Status

An investigational immunotherapy drug showed encouraging early results in patients with advanced non-small cell lung cancer (NSCLC), according to data presented at the 2026 ASCO Annual Meeting in Chicago.

The drug, pumitamig, is being developed jointly by BioNTech and Bristol Myers Squibb. It belongs to a newer class of medicines called bispecific antibodies — engineered proteins designed to block two targets at once rather than one. Pumitamig simultaneously blocks PD-L1, a protein cancer cells use to hide from immune cells, and VEGF-A, a protein that helps tumors grow new blood vessels and fuel their spread.

Researchers presented interim data from the phase 2 portion of the global ROSETTA Lung-02 trial, which is designed to find the right dose before moving into a larger, definitive phase 3 comparison. The phase 2 portion enrolled 44 patients with previously untreated advanced NSCLC who did not have actionable genetic mutations — meaning targeted therapy drugs were not an option for them. Patients were randomized to receive one of two doses of pumitamig combined with standard chemotherapy.

Among 40 patients evaluable for response, 70% responded to treatment, and every patient in the trial achieved at least some degree of disease control — a disease control rate of 100%. Tumors shrank by a median of 38.2% from baseline.

Why the PD-L1 finding matters

One of the most clinically meaningful aspects of the data involves a biomarker called PD-L1. Keytruda (pembrolizumab) and other standard immunotherapy drugs tend to work best in patients whose tumors express high levels of PD-L1 on their surface. Patients with low or no PD-L1 expression often see less benefit from those treatments.

In the ROSETTA Lung-02 data, pumitamig produced responses across all three PD-L1 subgroups — including patients whose tumors had less than 1% PD-L1 expression. If confirmed in the larger phase 3 trial, this could be significant for patients who are typically considered less likely to benefit from immunotherapy.

What the numbers showed by lung cancer type

NSCLC comes in two main histological subtypes — non-squamous and squamous — which are treated with different chemotherapy combinations. Pumitamig showed activity in both. Among patients with non-squamous NSCLC, the overall response rate was 66.7%. Among patients with squamous NSCLC, it was 73.7%.

Responses were also analyzed by dose. The lower dose — 1,400 mg — produced response rates of 72.7% in non-squamous and 81.8% in squamous disease, both higher than the rates seen with the larger 2,000 mg dose. Researchers selected the lower dose to carry forward into the ongoing phase 3 portion of the trial.

Safety

Nearly all patients — 93% — experienced at least one treatment-related side effect, which is expected in a chemotherapy combination regimen. Serious side effects of grade 3 or higher occurred in 44.2% of patients overall, though only 18.6% were considered related to pumitamig specifically. Side effects related to the immune system occurred in 14% of patients, with serious immune-related events in just 2.3%. Bleeding events, a known risk with drugs that block VEGF, occurred in 16.3% of patients, with only one event classified as serious. Treatment discontinuation due to pumitamig-related side effects was low, at 4.7%.

What comes next

At the time of the data cutoff, 69.8% of patients were still on treatment, and duration of response data were not yet mature — meaning researchers do not yet know how long responses will last. That question, along with overall survival, will be answered in the ongoing phase 3 portion of ROSETTA Lung-02, which is comparing pumitamig plus chemotherapy head-to-head against Keytruda plus chemotherapy — the current standard of care for many patients with advanced NSCLC without actionable mutations.

Pumitamig is investigational and has not been approved by the FDA. Patients interested in the ongoing phase 3 trial can ask their oncologist about eligibility or search for open ROSETTA Lung-02 sites at ClinicalTrials.gov (NCT06712316).

Reference

1. “Phase 2 data from ROSETTA Lung-02, a global randomized phase 2/3 trial of pumitamig (PD-L1 × VEGF-A bsAb) + chemotherapy in 1L NSCLC" by Dr. Solange Peters, et al. Presented at the 2026 ASCO Annual Meeting.

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