ClinicalTrials.gov recorded primary completion on 20 March 2024 for a Phase 3 study of pembrolizumab plus trastuzumab and chemotherapy in HER2-positive advanced gastric or gastroesophageal junction adenocarcinoma. Among 738 participants, median progression-free survival was 10.0 months with pembrolizumab plus standard-of-care treatment versus 8.1 months with standard of care alone.

Background

The trial studied pembrolizumab in combination with trastuzumab and standard-of-care chemotherapy for participants with HER2-positive gastric cancer. The conditions listed were gastric neoplasms and gastroesophageal junction adenocarcinoma. Registered interventions included pembrolizumab, placebo, cisplatin, 5-fluorouracil, and oxaliplatin.

Trial design

This completed Phase 3 trial enrolled 738 participants. It compared pembrolizumab plus trastuzumab with standard-of-care chemotherapy against trastuzumab plus standard-of-care chemotherapy. The study’s primary hypotheses concerned progression-free survival assessed by blinded independent central review using RECIST 1.1 and overall survival. The supplied record did not list separate primary outcome entries.

Key results

Global median progression-free survival was 10.0 months with pembrolizumab plus standard-of-care treatment and 8.1 months with standard of care. The progression-free survival analysis reported a hazard ratio of 0.73 with a 95% confidence interval of 0.61–0.87 and p=0.0002.

Median overall survival was 20.0 months in the pembrolizumab group and 16.8 months in the standard-of-care group. The reported overall survival hazard ratio was 0.80, with a 95% confidence interval of 0.67–0.94 and p=0.004.

  • Objective response rate: 72.6% with pembrolizumab plus standard of care versus 60.1% with standard of care; the difference was 12.6 percentage points (95% confidence interval, 5.6–19.4; p=0.0002).
  • Median duration of response: 11.13 months versus 9.5 months, respectively.
  • Participants experiencing an adverse event: 348 in the pembrolizumab group and 346 in the standard-of-care group.

What this means

In this registry analysis, adding pembrolizumab to trastuzumab and chemotherapy was associated with longer median progression-free and overall survival, a higher objective response rate, and longer median response duration than trastuzumab and chemotherapy alone. The supplied record reports adverse-event participant counts but does not provide an adverse-event summary or rates, so those counts alone do not establish a comparative safety conclusion. The event records trial completion and does not itself announce a new approval.

Source

Source: ClinicalTrials.gov, trial record for NCT03615326, with the event date listed as 20 March 2024. The registry record is available at clinicaltrials.gov/study/NCT03615326.