Early results from a clinical trial presented at the 2017 American Society of Clinical Oncology (ACSO) Annual Meeting found that combining an immunotherapy with a targeted therapy may be highly effective in patients with advanced prostate cancer.
Checkpoint immunotherapy, a treatment that reboots hibernating tumor-killing immune cells, has produced remarkable, sometimes curative results in patients with melanoma, lung cancer, and a number of other cancers, but so far has only benefitted a small fraction of patients with prostate cancer (<5% may respond). Meanwhile, recent PCF-funded studies have found that about 25% of advanced prostate cancer patients — those whose tumors have specific mutations – may respond to treatment with PARP-inhibitors, a type of targeted therapy. Simple math suggests that combining these two treatments in advanced prostate cancer might give response rates of perhaps 30%, if the treatments are additive. But if they are synergistic – meaning they somehow work together to amplify their activity – response rates could be much higher.
Dr. Fatima Karzai, a PCF Young Investigator and medical oncologist at the National Cancer Institute is leading a clinical trial that is testing the combination of the checkpoint immunotherapy durvalumab with the PARP-inhibitor olaparib, in metastatic hormone therapy-resistant prostate cancer. At ASCO, Dr. Karzai reported preliminary results from this trial, which found a remarkable 12 out of 17 (71%) patients had drops in their PSA levels, and 44% of men who had been on therapy for over 2 months had PSA drops of >50%.
“Providing men with advanced prostate cancer additional treatment options is of the utmost importance,” said Karzai. “While checkpoint immunotherapy has had limited success in metastatic prostate cancer in the past, combining this type of treatment with a PARP inhibitor, olaparib, regardless of whether a patient has a specific mutation that is targeted by olaparib, may provide patients with a novel treatment option that may provide clinical benefit. This treatment may lead to new strategies that harness the power of the immune system to treat prostate cancer and to help identify biomarkers that can help patients in the future.”
This trial is ongoing, and has recently been expanded to examine more patients, which will help Dr. Karzai and her team figure out why these therapies have had such a remarkable effect and identify which patients will most likely benefit from this treatment.