PT - JOURNAL ARTICLE AU - Daniel Gröner AU - Justus Baumgarten AU - Karen Davis AU - Christian Happel AU - Christina Nguyen Ngoc AU - Jennifer Wichert AU - Nicolai Mader AU - Philipp Mandel AU - Tselis Nikolaos AU - Frank Gruenwald AU - Amir Sabet TI - Hematotoxicity after Radioligand Therapy with <sup>177</sup>Lu-PSMA-617 in Patients with Metastastic Prostate Cancer DP - 2020 May 01 TA - Journal of Nuclear Medicine PG - 594--594 VI - 61 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/61/supplement_1/594.short 4100 - http://jnm.snmjournals.org/content/61/supplement_1/594.full SO - J Nucl Med2020 May 01; 61 AB - 594Introduction: Myelosuppression may be a dose-limiting factor in repeated cycles of radioligand therapy (RLT). This study aims to investigate the incidence, severity and reversibility of hematotoxicity in a large patient cohort with progressive metastatic prostate cancer undergoing RLT with 177Lu-PSMA-617. The impact of pre-existing risk factors and the cumulative administered activity were of particular interest. Methods: RLT was performed in 155 patients. Previous treatments included second-generation antiandrogenes (enzaltamide, abiraterone) in 115, at least one line of chemotherapy in 78, and 223Ra-dichloride in 66 patients. A mean activity of 6.7± 1.3 GBq 177Lu-PSMA-617 per cycle was administered in a median of 4 treatment cycles (IQR 2 to 5) at intervals of 6 to 8 weeks. Median cumulative activity was 19.0 GBq (IQR 11.4 to 35.2). Hematological parameters were measured at baseline, prior to each treatment course, 2 to 4 weeks thereafter and throughout follow-up. Toxicity was classified using Common Terminology Criteria for Adverse Events v5.0. Results: Significant treatment-induced hematotoxicity (grade 3 or 4) occurred in 18 patients (12 %), with anemia in 9% leukopenia in 5 % and thrombocytopenia in 5%. Bone marrow impairment was reversible throughout a median follow-up of 8 months (IQR 9 months) in all but two patients who died from disease progression within less than 3 months after RLT. Severe myelosuppression was significantly more frequent in patients with pre-existing grade 2 cytopenias (p=0.04) or high bone tumor burden (disseminated or diffuse based on PROMISE miTNM, p&lt;0.001). A history of chemotherapy, treatment with 223Ra-dichloride and cumulative RLT treatment activity were not associated with an increased incidence or higher degree of hematotoxicity (p=0.20, 0.15, 0.11) . Conclusion: Hematotoxicity after RLT is almost always reversible and has an acceptable overall incidence. High bone tumor burden and pre-existing moderate cytopenia (grade 2) were identified as risk factors for developing relevant hematotoxicity (grade 3 to 4). Previous chemotherapy, 223Ra-dichloride treatment or cumulative RLT activity have no impact on the incidence of significant hematoxicity.