Pfizer, Astellas' Xtandi racks up more data for new prostate cancer approval

Pfizer and Astellas’ Xtandi is gunning for a new indication in prostate cancer, and they say Sunday's new data complement the supporting evidence they’ve already generated. Sunday at the American Society of Clinical Oncology annual meeting, researchers trumpeted datafrom an investigator-sponsored study in metastatic hormone-sensitive prostate cancer (mHSPC). The study showed Xtandi slashed the risk of death by 33% compared with other non-steroidal androgen-fighting drugs. Eighty percent of men taking the Pfizer-Astellas drug were alive after three years compared with 72% of men who received the hormone-based chemo drugs bicalutamide, nilutamide or flutamide alongside standard treatment.The results from the phase 3 study, dubbed Enzamet and led by the Australian and New Zealand Urogenital and Prostate Cancer Trials Group, back up the companies’ own results from the phase 3 Arches trial. “The two studies actually are complementary of one another,” said Andrew Krivoshik, M.D., Astellas' vice president of medical science for oncology. The types of patients overlapped, but endpoints and eligibility criteria differed, he said. Arches, detailed in February, showed that combining Xtandi and androgen deprivation therapy (ADT) cut the risk of cancer worsening or death by 61% versus ADT alone. At the time of analysis, patients in the ADT-only group had gone a median 19.4 months before showing evidence of radiographic disease progression, an endpoint commonly used in prostate cancer trials. Meanwhile, in the Xtandi-ADT group, the median hadn’t yet been reached.