1. Quantitative imaging of RAD51 expression as a marker of platinum resistance in ovarian cancer
- Author
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Hoppe, MM, Jaynes, P, Wardyn, JD, Upadhyayula, SS, Tan, TZ, Lie, S, Lim, DGZ, Pang, BNK, Lim, S, Yeong, J, Karnezis, A, Chiu, DS, Leung, S, Huntsman, DG, Sedukhina, AS, Sato, K, Topp, MD, Scott, CL, Choi, H, Patel, NR, Brown, R, Kaye, SB, Pitt, JJ, Tan, DSP, Jeyasekharan, AD, Hoppe, MM, Jaynes, P, Wardyn, JD, Upadhyayula, SS, Tan, TZ, Lie, S, Lim, DGZ, Pang, BNK, Lim, S, Yeong, J, Karnezis, A, Chiu, DS, Leung, S, Huntsman, DG, Sedukhina, AS, Sato, K, Topp, MD, Scott, CL, Choi, H, Patel, NR, Brown, R, Kaye, SB, Pitt, JJ, Tan, DSP, and Jeyasekharan, AD
- Abstract
Early relapse after platinum chemotherapy in epithelial ovarian cancer (EOC) portends poor survival. A-priori identification of platinum resistance is therefore crucial to improve on standard first-line carboplatin-paclitaxel treatment. The DNA repair pathway homologous recombination (HR) repairs platinum-induced damage, and the HR recombinase RAD51 is overexpressed in cancer. We therefore designed a REMARK-compliant study of pre-treatment RAD51 expression in EOC, using fluorescent quantitative immunohistochemistry (qIHC) to overcome challenges in quantitation of protein expression in situ. In a discovery cohort (n = 284), RAD51-High tumours had shorter progression-free and overall survival compared to RAD51-Low cases in univariate and multivariate analyses. The association of RAD51 with relapse/survival was validated in a carboplatin monotherapy SCOTROC4 clinical trial cohort (n = 264) and was predominantly noted in HR-proficient cancers (Myriad HRDscore < 42). Interestingly, overexpression of RAD51 modified expression of immune-regulatory pathways in vitro, while RAD51-High tumours showed exclusion of cytotoxic T cells in situ. Our findings highlight RAD51 expression as a determinant of platinum resistance and suggest possible roles for therapy to overcome immune exclusion in RAD51-High EOC. The qIHC approach is generalizable to other proteins with a continuum instead of discrete/bimodal expression.
- Published
- 2021