Abiraterone may be more effective in black men

<p class="article-intro">In a prospective clinical trial of 100 men with metastatic castration-resistant prostate cancer, the response to the hormone treatment abiraterone was greater and longer lasting in black men than in white men.</p> <hr /> <p class="article-content"><p>The Abi Race clinical trial enrolled 100 men with metastatic castration-resistant prostate cancer (mCRPC) of whom 50 self-identified as white and 50 self-identified as black. The men received a standard treatment regimen for this disease &ndash; abiraterone acetate and prednisone &ndash; until the cancer worsened or unacceptable side effects arose. Cancer worsening was assessed through imaging scans (radiographic progression-free survival, rPFS) and by measuring PSA level in the blood (PSA PFS). This pilot study was aimed at demonstrating feasibility and describing responses and side effects by race. The researchers also conducted exploratory research on genetic ancestry, as well as on differences in genomic markers, metabolism, and hormone levels by race.</p> <p>The time to radiographic disease progression was similar between the two cohorts, but when the researchers looked at PSA they found differences by race. Abiraterone was more effective at both lowering PSA and delaying PSA progression in black men than in white men. The median PSA PFS was 16,8 months in black men and 11,5 months in white men. After treatment with abiraterone, a greater percentage of black men than white men had a PSA decline of: 90 % or more (48 % vs. 38 % ), 50 % or more (76 % vs. 66 % ) and 30 % or more (86 % vs. 76 % ).<br /> In addition, more white patients than black patients (8 vs. 4) had no PSA decline. Based on imaging scans, black men did not have worse outcomes than white men -- the median rPFS was the same for black men and white men (16,8 months).<br /> Most side effects were similar by race, but fatigue occurred more often in white patients than black patients (40 % vs. 26 % ). In addition, twice as many black men than white men experienced low potassium level (36 % vs. 18 % ), a complication directly related to the effect of abiraterone on adrenal hormones, which can be life-threatening if not corrected.</p> <p>This study shows that prospective research of cancer outcomes by race is feasible, laying the groundwork for future studies. Another 100-patient study exploring outcomes of treatment with abiraterone in combination with apalutamide is underway. The researchers are also co-leading an initiative to study all treatments of men with advanced prostate cancer through a global registry of 5000 patients called IRONMAN. Although this study was small, the differences in PSA response observed in this study suggest that the biology driving advanced prostate cancer may be different in black men and white men. Research shows that hormone levels and hormone metabolism tend to be different in black men and white men, and these differences may be contributing to variances in PSA response. The researchers plan to conduct a molecular analysis of blood and tissue samples collected in this study to gain more insight into the factors that might be driving differences in outcomes.</p> <p><br /><strong>Reference:</strong><br />George DJ et al.: Abi Race: A prospective, multicenter study of black (B) and white (W) patients (pts) with metastatic castrate resistant prostate cancer (mCRPC) treated with abiraterone acetate and prednisone (AAP). ASCO Annual Meeting 2018, abstract # LBA5009</p></p>