Race does not affect docetaxel/prednisone response

Race does not affect oncologic response to treatment with docetaxel (Taxotere)/prednisone in men with metastatic castrate-resistant prostate cancer (mCRPC), according to research presented at the American Society of Clinical Oncology annual meeting in Chicago.

Results of the study that included data from patients enrolled in nine phase III randomized clinical trials showed that the likelihood of achieving either a PSA response or an objective response was similar among African-Americans and Asians compared with their Caucasian counterparts.

“Data reported from the National Cancer Institute (NCI) show that the mortality rate from prostate cancer is higher among African-American men compared with white men, and there is very little information about the outcomes of Asian patients compared with whites. Results from our study show that when outcomes are analyzed from a more homogenous patient population enrolled in clinical trials, the minorities respond as well to docetaxel/prednisone as white men. Our findings are consistent with analyses from studies of other treatments for mCRPC that show blacks do as well or better than whites,” said W. Kevin Kelly, DO, professor of medical oncology and urology at Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia.

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“This information supports the idea that race itself is not a factor in differences in prostate cancer-related mortality and the need for further studies to understand the reasons for the disparity in overall outcomes for black men with prostate cancer.”

The trials included in the analysis enrolled approximately 9,600 men. Identification of patient race was based on self-report. Within the evaluable populations, 85% of men were Caucasian, approximately 6% were African-American, approximately 5% were Asian, and race was unknown in 4%.

“Overall, there was low enrollment of blacks and Asians in these randomized clinical trials, although the NCI National Clinical Trials Network studies were reasonably successful in enrolling black men and Asian patients,” said Dr. Kelly.

“Understanding possible differences in treatment response among Asian men is an important issue because Asians represent a growing segment of the population and considering evidence showing differences in drug metabolism in Asians versus whites,” he told Urology Times.

The analysis for PSA response included 7,375 evaluable patients and identified men who achieved a ≥50% PSA decline from baseline defined by the PSA Working Group 2. It found that the proportion of patients who achieved the PSA endpoint was similar across the African-American, Asian, and Caucasian racial groups (58%, 62%, and 64%, respectively).

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Results of a logistic regression analysis adjusting for established prognostic variables (treatment arm, performance status, age, PSA, hemoglobin, alkaline phosphatase, and site of metastases) found that race did not independently predict PSA response.

Objective response was defined as complete or partial response, and was analyzed for 2,760 evaluable men. The results showed that similar proportions of African-Americans, Asians, and Caucasians achieved an objective response (31%, 34%, and 39%, respectively). The logistic regression analysis found that race was not independently associated with objective response.

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The research was supported by the U.S. Department of Defense. Dr. Kelly has received honoraria from Constellation Pharma and Janssen Oncology; has served as a consultant/adviser to Foundation Medicine and Sanofi; has received institutional research funding from Bayer, Endocyte, Exelixis, Janssen Oncology, Novartis, Sanofi, and Seattle Genetics; and has received travel, accommodations, and expenses from Janssen Oncology. For full disclosures, see bit.ly/5021disclosures.