The presence of lymph node metastases and time to castration resistance predict the therapeutic effect of enzalutamide for castration-resistant prostate cancer.

Enzalutamide is effective against castration-resistant prostate cancer (CRPC). However, it is unclear which patients would benefit more from enzalutamide treatment. Here, we analyzed patients who received enzalutamide as first-line therapy for CRPC and evaluated the factors that predict treatment response and prognosis.

We retrospectively analyzed 101 patients treated with enzalutamide for CRPC at our institution. As primary endpoints we regarded the prostate-specific antigen (PSA) response rate and PSA-progression-free survival (PSA-PFS) from the start of enzalutamide treatment. Laboratory and imaging data were analyzed to predict treatment efficacy.

PSA reductions of ≥ 50% and ≥ 90% were observed in 78 (77%) and 47 (47%) patients, respectively, compared with the baseline. During the follow-up period, 67 (66%) patients showed PSA progression, with a median PSA-PFS of 11 months. Moreover, 31 patients (31%) died, with a median overall survival of 64 months. On multivariate analysis, lymph node metastases at the start of enzalutamide treatment [odds ratio (OR) 0.0575, 95% confidence interval (CI) 0.0105-0.316, p = 0.0010] and time to CRPC (OR 0.177, 95% CI 0.0428-0.731, p = 0.0167] were associated with ≥ 90% PSA response. Lymph node metastases (hazard ratio [HR] 3.00, 95% CI 1.48-6.09, p = 0.0023) and time to CRPC (HR 1.84, 95% CI 1.02-3.30, p = 0.0419) were also predictors of PSA-PFS on a multivariate model.

Time to CRPC and lymph node metastasis were predictors of the PSA response rate and PSA-PFS.

International journal of clinical oncology. 2022 Dec 29 [Epub ahead of print]

Toshiki Oka, Koji Hatano, Yohei Okuda, Akinaru Yamamoto, Toshihiro Uemura, Gaku Yamamichi, Eisuke Tomiyama, Yu Ishizuya, Yoshiyuki Yamamoto, Taigo Kato, Atsunari Kawashima, Kazutoshi Fujita, Norio Nonomura

Department of Urology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan., Department of Urology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. ., Department of Urology, Kindai University Faculty of Medicine, 377-2, Ohno-Higashi, Sayama, Osaka, 589-8511, Japan.