Data from the highly anticipated PROMISE-meso trial failed to deliver, with no PFS or OS benefit seen for pembrolizumab compared to standard chemotherapy.
The Phase III trial, presented at the European Society for Medical Oncology Congress 2019 in Barcelona, involved 144 patients with advanced pre-treated mesothelioma who were randomised to pembrolizumab (200 mg every three weeks) or chemotherapy (gemcitabine/vinorelbine). Patients in the control group were able to cross over to pembrolizumab at progression.
Patients treated with pembrolizumab (Keytruda) had a median progression-free survival (PFS) of 2.5 months compared to 3.4 months with standard chemotherapy regimens (p=0.76). Analysis of PFS by PD-L1 expression status also showed no advantage for pembrolizumab.
Median overall survival was 10.7 months for pembrolizumab vs 11.7 months for chemotherapy (p=0.85).
Treatment-related adverse events grade ≥3 were experienced by 19% of patients in the pembrolizumab group and 24% in the chemotherapy group, one fatal in each group.
Lead researcher Dr Sanjay Popat from the Royal Marsden Hospital NHS Foundation Trust, London, UK, said that while the results were disappointing, nearly four times more patients responded to immunotherapy than standard chemotherapy (ORR was 22% in patients treated with pembrolizumab compared to 6% with chemotherapy (p=0.004).