Updates from ASCO's Genitourinary Cancers Symposium.
This year marks the 10th anniversary of the oncology meeting devoted to genitourinary cancers, which includes prostate, kidney and bladder. The American Society of Clinical Oncology’s Genitourinary Cancers Symposium, held Jan. 30 to Feb. 1 in San Francisco, presented several studies that may impact clinical practice and future research in genitourinary cancers. Here are a few notable findings.
Men with advanced prostate cancer are typically given hormone therapy (androgen deprivation) until the disease progresses, at which point the next option is usually chemotherapy. Because prostate cancer is generally a slow-growing disease, delaying time to chemotherapy has been one goal in treatment. Xtandi (enzalutamide), an oral drug that blocks the androgen receptor, was approved in 2012 after it was shown to extend survival for men whose metastatic, castration-resistant prostate cancer had progressed on docetaxel.
The results of the phase 3 PREVAIL study showed that when men were given Xtandi before chemotherapy, the drug delayed disease progression, improved survival, delayed time to chemotherapy and improved quality of life.
The trial randomized more than 1,700 men who had few or no symptoms of their advanced prostate cancer to receive Xtandi or a placebo. Overall, Xtandi delayed the time to chemotherapy by about 17 months. Side effects were minimal and similar in both groups of patients and included fatigue, back pain, constipation and hypertension.
The interim results clearly showed the benefit of Xtandi, which led an independent data-monitoring committee to recommend that the trial be stopped early and patients receiving placebo be offered Xtandi.
“I think it’s safe to say that enzalutamide provided a significant clinical benefit to patients with metastatic castration-resistant prostate cancer,” said Tomasz Beer, lead author of the study, as he concluded the presentation.
After disease progression, participants in the trial received other therapies, including docetaxel, Zytiga (abiraterone), Jevtana (cabazitaxel), Provenge (sipuleucel-T) and Xtandi, many of which were approved in the past few years—a testament to the advances in prostate cancer treatment.
High blood pressure medications called angiotensin system inhibitors (ASIs) impact blood flow to a tumor, which could make them an ideal addition to cancer treatment. Researchers looked at data from several studies that included participants with metastatic kidney cancer who received ASIs within the first 30 days of a clinical trial. Those trials were testing a variety of anticancer drugs, including Avastin (bevacizumab), Sutent (sunitinib), Torisel (temsirolimus) and interferon alfa. (You can view the results here.)
Retrospective data showed participants who took blood pressure medication along with their anticancer drug had longer survival and delayed tumor progression. Participants who received an antiangiogenic drug, such as Avastin (a drug that blocks blood flow to a tumor), along with an ASI experienced even more significant results, with an improvement in survival time of nine months compared with participants not receiving an ASI. Study subjects receiving an ASI and an mTOR inhibitor or interferon alfa did not experience a significant improvement.
Researchers are not encouraging the use of ASIs in nonhypertensive patients with advanced kidney cancer, but patients who have high blood pressure and receive antiangiogenic cancer treatment should certainly consider ASIs.