Improved response rates without survival benefit with pembrolizumab in pretreated mesothelioma

Results from the PROMISE-meso study showed better response rates but no survival benefit in pretreated mesothelioma patients treated with pembrolizumab monotherapy compared with chemotherapy. Nonetheless, current results are encouraging and the results of investigations of checkpoint inhibitor treatments in earlier stage mesothelioma are eagerly awaited [1].

PROMISE-meso randomised 144 patients with advanced pre-treated mesothelioma to either immune checkpoint inhibitor pembrolizumab (200 mg every 3 weeks) or to investigators’ choice of standard chemotherapy (gemcitabine or vinorelbine). Patients in the control group were able to cross over to pembrolizumab at progression. Nearly 4 times more patients responded to immunotherapy. The objective response rate was 22% in patients with pembrolizumab compared with 6% with chemotherapy (P=0.004). Median progression-free survival was 2.5 months (95% CI 2.1 to 4.2) and 3.4 months (95% CI 2.2 to 4.3) respectively (P=0.76). 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, with 1 fatal adverse event in each group.

“In PROMISE-meso, significantly more patients responded to immunotherapy than to standard chemotherapy, but unfortunately these responses did not delay progression or improve survival. These findings are disappointing but, as in previous studies, some patients benefitted from immunotherapy for long periods. If we can find out how this happens, we will have a better idea of which patients should preferentially receive this treatment over chemotherapy,” said study author Dr Sanjay Popat (Royal Marsden Hospital NHS Foundation Trust, UK). “Nevertheless, whilst pembrolizumab was not superior to chemotherapy, survival was similar, and so pembrolizumab may represent an alternative.”

1. Popat S et al. ESMO Congress 2019. Abstract LBA91_PR.

Posted on 26 November 201918 March 2021