Exelixis, Inc. (NASDAQ:EXEL) today announced that it has initiated a phase 2 clinical trial comparing cabozantinib plus abiraterone and prednisone (abiraterone/prednisone) versus abiraterone/prednisone in patients with castration-resistant prostate cancer (CRPC) who have bone metastases and have not been previously treated with chemotherapy. The primary endpoint for the randomized, open-label trial is radiographic progression-free survival (PFS).
“A growing body of data support the potential clinical utility of cabozantinib in treating patients with metastatic CRPC,” said Christopher Sweeney, MBBS, clinical director, genitourinary oncology at the Dana-Farber Cancer Institute in Boston, and the lead investigator on the phase 2 trial. “Phase 1 experience from our institution provided important insight into clinical activity when cabozantinib is administered in combination with full dose abiraterone in this patient population, opening the door to potential new treatment options for CRPC patients who have bone metastases but have not yet received chemotherapy. Continued study of cabozantinib in a variety of CRPC indications may help to advance the treatment of the disease.”
The phase 2 trial will compare abiraterone/prednisone against abiraterone/prednisone in combination with one of the three cabozantinib doses: 40 mg daily, 20 mg daily, or 20 mg every other day. The trial is expected to enroll 280 chemotherapy-naïve CRPC patients who have bone metastases, and will be conducted at approximately 50 sites in North America. In addition to evaluating radiographic PFS, the trial includes pre-specified outcome measures of safety and tolerability, pharmacokinetics of cabozantinib in combination with abiraterone, overall survival (OS), and bone scan response by computer-aided detection.
“With its differentiated mechanism targeting MET, RET, and VEGFR2, we believe cabozantinib has the potential to be therapeutically complementary with prostate cancer therapies such as abiraterone and enzalutamide,” said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis. “We believe that the results of this trial will provide important insight into the role that cabozantinib might play in earlier lines of therapy, including patients who have not yet received chemotherapy. This trial, and our planned phase 1 trial of cabozantinib in combination with enzalutamide, which is expected to start in the first half of 2014, should support our efforts to realize the full clinical and commercial potential of cabozantinib in CRPC.”