Title: Clinical safety and activity of pembrolizumab in patients with malignant pleural mesothelioma (KEYNOTE-028): preliminary results from a non-randomised, open-label, phase 1b trial

Alley, EW et al.


What You Need to Know:

An interim analysis found that pembrolizumab, an anti-programmed cell death receptor 1 (PD-1) antibody, seemed well tolerated and may exert anti-tumor activity in patients with PD-L1-positive malignant pleural mesothelioma.

Trial Design:

  • Patients with PD-L1-positive malignant pleural mesothelioma who were previously treated received pembrolizumab 10mg/kg every 2 weeks for up to 2 years or until confirmed progression or unacceptable toxicity
  • PD-L1 positivity was defined as expression in ≥1% of tumor cells by immunohistochemistry
  • Response was assessed based on investigator review using RECIST (version 1.1)
  • Primary endpoints were safety and tolerability analyzed in the all-patients-as-treated population, and objective response analyzed for the full-analysis set

Key Outcomes:

  • Of the 25 patients who received pembrolizumab, 16 (64%) had a treatment-related adverse event (eg, fatigue, nausea, arthralgia)
  • Grade 3 treatment-related adverse events were reported in 5 (20%) of patients and 3 patients (12%) needed a dose interruption due to immune-related adverse events
  • No treatment-related deaths of discontinuations reported
  • 5 patients had a partial responses (objective response 20%, 95% CI: 6.8–40.7); 13 patients had stable disease
  • Median response duration was 12 months (95% CI: 3.7–not reached)
  • Response durability and efficacy in this patient group calls for more research