Trial results for a Phase 2 study (NCT05775289) comparing pembrolizumab plus platinum-based chemotherapy to tobemstomig plus platinum-based chemotherapy in participants with previously untreated non-small cell lung cancer (NSCLC) were posted on ClinicalTrials.gov on 2025-11-19. The study reported a median progression-free survival (PFS) of 7.13 months for the pembrolizumab arm, with a hazard ratio of 0.99 (95% CI: 0.63 to 1.56) for PFS comparing the two regimens.
Background
The study investigated treatment options for participants with previously untreated, locally advanced, unresectable (Stage IIIB/IIIC) or metastatic (Stage IV) non-small-cell lung cancer (NSCLC) who are not eligible for curative surgery and/or definitive chemoradiotherapy. Pembrolizumab is an established immunotherapy, and this trial compared its combination with platinum-based chemotherapy against a novel agent, tobemstomig, also combined with platinum-based chemotherapy.
Trial design
The study (NCT05775289) was a Phase 2 trial with an enrollment of 182 participants. It evaluated the efficacy, safety, and pharmacokinetics of tobemstomig in combination with platinum-based chemotherapy compared with pembrolizumab plus platinum-based chemotherapy. Participants had previously untreated, locally advanced, unresectable (Stage IIIB/IIIC) or metastatic (Stage IV) non-small-cell lung cancer (NSCLC). The chemotherapy regimens included paclitaxel, pemetrexed, and carboplatin. Key outcomes measured included Progression-Free Survival (PFS), Objective Response Rate (ORR), and Overall Survival (OS).
Key results
Results from the trial showed the following for key efficacy outcomes:
- For Progression-Free Survival (PFS), the pembrolizumab plus chemotherapy group had a median PFS of 7.13 months. The tobemstomig plus chemotherapy group had a median PFS of 7.62 months.
- An analysis of PFS yielded a Hazard Ratio (HR) of 0.99 (95% Confidence Interval: 0.63 to 1.56) with a p-value of 0.9705.
- For Objective Response Rate (ORR), the pembrolizumab plus chemotherapy group had an ORR of 46.2 Percent of participants. The tobemstomig plus chemotherapy group had an ORR of 41.1 Percent of participants.
- An analysis of ORR yielded an Odds Ratio (OR) of 0.77 (95% Confidence Interval: 0.42 to 1.43) with a p-value of 0.4056.
- For Overall Survival (OS), the tobemstomig plus chemotherapy group had a median OS of 13.17 months. Data for the pembrolizumab plus chemotherapy group was not available.
- Regarding participant-reported outcomes for Physical Functioning (assessed by EORTC), the median score for the pembrolizumab plus chemotherapy group was 86.67 (Full Range) and 80.00 (Full Range). For the tobemstomig plus chemotherapy group, median scores were 80.00 (Full Range) and 93.3 (Full Range).
What this means
The results of this Phase 2 trial suggest that pembrolizumab plus platinum-based chemotherapy demonstrated comparable efficacy to tobemstomig plus platinum-based chemotherapy in terms of Progression-Free Survival and Objective Response Rate in participants with previously untreated advanced NSCLC. The hazard ratio for PFS and the odds ratio for ORR, both with p-values above 0.05, indicate no statistically significant difference between the two treatment arms for these endpoints. The incomplete Overall Survival data for the pembrolizumab arm limits a full comparison of this outcome. These findings provide initial insights into the comparative performance of these regimens in this patient population.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT05775289, titled "A Study of Tobemstomig Plus Platinum-Based Chemotherapy vs Pembrolizumab Plus Platinum-Based Chemotherapy in Participants With Previously Untreated Non-Small Cell Lung Cancer," were posted on 2025-11-19 on clinicaltrials.gov.