Tolerability of PSMA radioligand therapy in metastatic prostate cancer patients with baseline mild to moderate leukopenia

Abstract

Background Aim of this study was to analyze the safety of prostate-specifc membrane antigen radioligand therapy (PSMA-RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC) with preexisting mild to moder‑ ate leukopenia (CTCAE≥1). Results Thirty-seven mCRPC patients with preexisting leukopenia (leukocyte count<3.8× 109 /L) were included in this study. Patients received a median of 3 cycles of [ 177Lu]Lu-PSMA-617 (range 1–9). No signifcant diference in leu‑ kocyte counts was observed between baseline and follow-up after each PSMA-RLT cycle: frst cycle (3.0±0.5 at base‑ line vs. 3.4±1.4 at follow up [in× 109 /L], p=0.0921), second cycle (3.1±0.4 vs. 3.8±1.7, p=0. 0.0509), and third cycle (3.1±0.4 vs. 3.2±2.0, p=0.2929), respectively. Similarly, baseline and end of treatment values, irrespective of the num‑ ber of administered cycles, did not reveal a signifcant diference (3.0±0.5 vs. 3.5±1.4, p=0.0684). After the end of therapy, irrespective of the number of administered cycles, 27% patients remained stable in terms of CTCAE scor‑ ing, 46% changed to a higher score and 27% improved to a lower score. Conclusion Although marked preexisting leukopenia is often considered a relative contraindication for PSMA-RLT, our fndings indicate that PSMA-RLT is feasible in patients with leukopenia of CTCAE grade ≥1. In our cohort, leuko‑ cyte counts remained stable without signifcant RLT-induced deterioration. Therefore, patients with leukopenia should not be categorically excluded from receiving PSMA-RLT. Trial registration: Clinicaltrials.gov identifer: NCT04833517, registered 01.01.2016.