Around one in ten men with advanced and otherwise untreatable prostate cancer benefit from treatment with the immunotherapy drug pembrolizumab, study results show
The trial involved 258 men with prostate cancer who were no longer responding to hormonal or chemotherapy treatment. They received pembrolizumab every 3 weeks for 35 weeks or until progression or intolerable toxicity.
Across all patients, the rate of disease control or response lasting six months or more was 11%, including two patients who had a complete response. However, unlike in other tumour types treated with pembrolizumab, PD-L1 status did not predict response.
The researchers said that future studies should look at how to identify which patients will respond to pembrolizumab.
Presenting the findings at the American Society of Clinical Oncology’s annual meeting on 4 June 2018 in Chicago, Illinois, Johann de Bono from the Institute of Cancer Research, London, said: “Our study has found that immunotherapy can benefit a subset of men with advanced, otherwise untreatable prostate cancer, and these are most likely to include patients who have specific DNA repair mutations within their tumours.”
 De Bono J, Goh J, Ojamaa K et al. KEYNOTE-199: Pembrolizumab (pembro) for docetaxel-refractory metastatic castration-resistant prostate cancer (mCRPC). Presented at 2018 ASCO Annual Meeting; 1–5 June 2018; Chicago, Illinois. J Clin Oncol 36, 2018 (suppl; abstr 5007). Abstract available here: http://abstracts.asco.org/214/AbstView_214_224563.html (accessed August 2018)