Hematologic safety of 177Lu-PSMA-617 radioligand therapy in patients with metastatic castration-resistant prostate cancer

Abstract

Background Myelosuppression is a potential dose-limiting factor in radioligand therapy (RLT). This study aims to investigate occurrence, severity and reversibility of hematotoxic adverse events in patients undergoing RLT with 177 Lu-PSMA-617 for metastatic castration-resistant prostate cancer (mCRPC). The contribution of pretreatment risk factors and cumulative treatment activity is taken into account specifically. Methods RLT was performed in 140 patients receiving a total of 497 cycles. A mean activity of 6.9 $$\\pm$$ ± 1.3\xa0GBq 177 Lu-PSMA-617 per cycle was administered, and mean cumulative activity was 24.6 $$\\pm$$ ± 15.9\xa0GBq. Hematological parameters were measured at baseline, prior to each treatment course, 2 to 4\xa0weeks thereafter and throughout follow-up. Toxicity was graded based on Common Terminology Criteria for Adverse Events v5.0. Results Significant (grade\u2009≥\u20093) hematologic adverse events occurred in 13 (9.3%) patients, with anemia in 10 (7.1%), leukopenia in 5 (3.6%) and thrombocytopenia in 6 (4.3%). Hematotoxicity was reversible to grade\u2009≤\u20092 through a median follow-up of 8 (IQR 9) months in all but two patients who died from disease progression within less than 3\xa0months after RLT. Myelosuppression was significantly more frequent in patients with pre-existing grade 2 cytopenia (OR: 3.50, 95%CI 1.08–11.32, p \u2009=\u20090.04) or high bone tumor burden (disseminated or diffuse based on PROMISE miTNM, OR: 5.08, 95%CI 1.08–23.86, p \u2009=\u20090.04). Previous taxane-based chemotherapy was associated with an increased incidence of significant hematotoxicity (OR: 4.62, 95%CI 1.23–17.28, p \u2009=\u20090.02), while treatment with 223 Ra-dichloride, cumulative RLT treatment activity and activity per cycle were not significantly correlated ( p \u2009=\u20090.93, 0.33, 0.29). Conclusion Hematologic adverse events after RLT have an acceptable overall incidence and are frequently reversible. High bone tumor burden, previous taxane-based chemotherapy and pretreatment grade 2 cytopenia may be considered as risk factors for developing clinically relevant myelosuppression, whereas cumulative RLT activity and previous 223 Ra-dichloride treatment show no significant contribution to incidence rates.