According to results from the phase 2 GALAXIES Lung-201 study, the addition of belrestotug, a differentiated anti-TIGIT monoclonal antibody, to dostarlimab demonstrates antitumor activity among patients with PD-L1-high locally advanced or metastatic non-small cell lung cancer (NSCLC). 

These results were presented by David Spigel, MD, Sarah Cannon Research Institute, Nashville, Tennessee, at the 2024 European Society for Medical Oncology (ESMO) Congress. 

In this open-label study, 124 patients with unresectable, previously untreated, locally advanced or metastatic NSCLC with a PD-L1 of ≥50% and no actionable mutations were randomized to receive 500 mg of dostarlimab alone (n = 32) or in combination with either 100 mg (n = 30), 400 mg (n = 32), or 1000 mg (n = 30) of belrestotug every 3 weeks until disease progression, unacceptable toxicity, or death. The primary end point was investigator-assessed objective response rate (ORR). A key secondary end point was safety. 

At a median follow-up of 7.3 months, 65% of patients remained on study treatment. The ORR was 37.5% in the dostarlimab monotherapy arm, 63.3% in the 100 mg of belrestotug arm, 65.6% in the 400 mg of belrestotug arm, and 76.7% in the 1000 mg of belrestotug arm. Confirmed ORR was 28.1%, 60%, 59.4%, and 63.3%, respectively. 

Treatment-related adverse events occurred in 59% of patients in the dostarlimab monotherapy arm, 80% of patients in the 100 mg of belrestotug arm, 84% of patients in the 400 mg of belrestotug arm, and 97% of patients in the 1000 mg of belrestotug arm. Grade ≥3 treatment-related adverse events occurred in 16%, 33%, 22%, and 43% of patients, respectively. 

Treatment discontinuation due to treatment-related adverse events occurred in 6% of patients in the dostarlimab monotherapy arm, 23% of patients in the 100 mg of belrestotug arm, 16% of patients in the 400 mg of belrestotug arm, and 40% of patients in the 1000 mg of belrestoutug arm. 

As Dr Spigel et al concluded, “these data support the ongoing GALAXIES Lung-301 phase 3 study of belrestotug and dostarlimab in patients with previously untreated PD-L1-high advanced NSCLC.” 

Source: 

Spigel DR. Korbenfeld EP, Hatashi H, et al. Interim analysis of GALAXIES Lung-201: Phase II, randomized, open-label platform study of belrestotug plus dostarlimab in patients (pts) with previously untreated locally advanced/metastatic (LA/M) PD-L1 high (TPS >/=50%) non-small cell lung cancer (NSCLC). Presented at 2024 ESMO Congress. September 13-17, 2024. Abstract LBA52