Dr. Morris and colleagues presented the results of their phase I/IIa clinical trial, which aimed to assess the safety and efficacy of combination radium-223 and docetaxel vs. docetaxel alone in patients with bone-metastatic castration-resistant prostate cancer. As part of the efficacy testing, bone biomarkers (tALP, P1NP, bALP, uCTX-1, and ICTP) were checked during the study to further elucidate the effects of combination therapy on bony metastatic disease pathophysiology and tumor microenvironment. The study included 46 patients, of which 33 underwent combination treatment and 13 were treated solely with docetaxel.
The median time to prostate-specific-antigen progression was longer with combination therapy than with docetaxel alone (7 vs. 5 months, P = .020). Combination therapy was also associated with greater declines in tALP and bone formation markers bALP and P1NP. With regard to safety, the combination of radium-223 and docetaxel was well-tolerated, with no greater safety concern than treatment with docetaxel alone. The most common side effect was neutropenia, which was seen in 30% of participants in the combination arm compared to 38% who received only docetaxel.
In conclusion, Dr. Morris and his associates noted that the combination of radium-223 and docetaxel is safe and appears to have added effect in bone pathophysiology, which may help explain the difference in progression-free survival. But the researchers advised that the findings should be further validated in a larger trial to confirm the association between clinical outcomes and biomarker response.
PRESENTED BY: MICHAEL MORRIS, MD, MEMORIAL SLOAN KETTERING CANCER CENTER, NEW YORK CITY
Andres F. Correa
Society of Urologic Oncology Fellow
Fox Chase Cancer Center-Temple Health from the 2017 Genitourinary Cancers Symposium - February 16 - 18, 2017 – Orlando, Florida USA