Abstract 7629: Association between COMT expression and therapeutic efficacy of androgen receptor-axis targeted in prostate cancer

Abstract Background: The enzyme of catechol-O-methyltransferase (COMT) inhibits the proliferation of prostate cancer (PCa). There has been no obvious biomarker that contributes to the selection of a therapeutic agent among new-generation androgen receptor-axis targeted (ARAT) therapy, such as abiraterone (ABI) or enzalutamide (ENZ). We aimed to assess the possibility of using COMT expression as a biomarker for PCa progression and the criteria for selecting ABI or ENZ. Methods: We retrospectively evaluated 60 patients with PCa treated with ABI or ENZ via needle biopsy or radical prostatectomy. Immunostaining of COMT was performed using formalin-fixed, paraffin-embedded blocks obtained from the initial prostate biopsy for diagnosis or prostatectomy. Immunostaining evaluations were scored by immunostaining intensity (0-3) and staining area (0-3), and the total score ≥4 was defined as "high expression" and the total score <4 was defined as "low expression.” The associations between COMT expression levels and clinical outcomes, including the duration of ENZ or ABI response, were also assessed. Results: Of the 60 cases, nine (15%) showed low expression of COMT. Overall survival was significantly shorter in patients with lower COMT expression (hazard ratio [HR] = 0.24, 95% confidence interval [CI] 0.07-0.83, P= 0.024). When ENZ was administered as the first ARAT, progression-free survival (PFS) was significantly different between patients with COMT expression scores <4 and ≥4 (median 5.9 and 23.3 months, respectively). However, when ABI was administered as the first ARAT, there was no significant difference in the PFS of ARAT between COMT expression scores <4 and ≥4. Conclusion: Patients with lower COMT expression have a significantly poorer prognosis for PCa. In addition, PFS after ENZ administration, as the first ARAT, correlated with COMT expression levels. To our knowledge, this is the first report of an association between COMT expression and the duration of ARAT. Citation Format: Shigekatsu Maekawa, Ryo Takata, Ei Shiomi, Daiki Ikarashi, Tomohiko Matsuura, Renpei Kato, Mitsugu Kanehira, Jun Sugimura, Wataru Obara. Association between COMT expression and therapeutic efficacy of androgen receptor-axis targeted in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7629.