Comprehensive genomic profiling and treatment patterns across ancestries in advanced prostate cancer: a large-scale...

Men of African ancestry experience the greatest burden of prostate cancer globally, but they are under-represented in genomic and precision medicine studies. Therefore, we sought to characterise the genomic landscape, comprehensive genomic profiling (CGP) utilisation patterns, and treatment patterns across ancestries in a large, diverse, advanced prostate cancer cohort, to determine the impact of genomics on ancestral disparities.

In this large-scale retrospective analysis, the CGP-based genomic landscape was evaluated in biopsy sections from 11 741 patients with prostate cancer, with ancestry inferred using a single nucleotide polymorphism-based approach. Admixture-derived ancestry fractions for each patient were also interrogated. Independently, clinical and treatment information was retrospectively reviewed for 1234 patients in a de-identified US-based clinicogenomic database. Prevalence of gene alterations, including actionable gene alterations, was assessed across ancestries (n=11 741). Furthermore, real-world treatment patterns and overall survival was assessed in the subset of patients with linked clincogenomic information (n=1234).

The CGP cohort included 1422 (12%) men of African ancestry and 9244 (79%) men of European ancestry; the clinicogenomic database cohort included 130 (11%) men of African ancestry and 1017 (82%) men of European ancestry. Men of African ancestry received more lines of therapy before CGP than men of European ancestry (median of two lines [IQR 0-8] vs one line [0-10], p=0·029). In genomic analyses, ancestry-specific mutational landscapes were observed, but the prevalence of alterations in AR, the DNA damage response pathway, and other actionable genes were similar across ancestries. Similar genomic landscapes were observed in analyses that accounted for admixture-derived ancestry fractions. After undergoing CGP, men of African ancestry were less likely to receive a clinical study drug compared with men of European ancestry (12 [10%] of 118 vs 246 [26%] of 938, p=0·0005).

Similar rates of gene alterations with therapy implications suggest that differences in actionable genes (including AR and DNA damage response pathway genes) might not be a main driver of disparities across ancestries in advanced prostate cancer. Later CGP utilisation and a lower rate of clinical trial enrolment observed in men of African ancestry could affect genomics, outcomes, and disparities.

American Society for Radiation Oncology, Department of Defense, Flatiron Health, Foundation Medicine, Prostate Cancer Foundation, and Sylvester Comprehensive Cancer Center.