Selective Intra-Arterial 177Lu-PSMA Therapy for Castration Resistant Prostate Cancer: Preliminary Results of a Pilot Study

Abstract

Purpose177Lu-PSMA is a promising therapy for patients with metastatic castration resistant prostate cancer patients (mCRPC). To our knowledge, no study has compared the pharmacokinetic profiles of 177Lu-PSMA therapy delivered intra-arterially. We aimed to compare the feasibility and safety of selective intra-arterial (IA) administration vs conventional intravenous (IV) administration of 177Lu-PSMA in mCRPC. MethodsIn this within-patient pilot study, four patients (median age, 62.5; range, 53-72) with mCRPC who were referred to our clinic between January 2018 and September 2019 for treatment with 177Lu-PSMA. Patients were treated in two visits; in each visit receiving half of the total empiric therapeutic dose of 200 mCi, IV at the first visit and IA at the second visit. They were followed upto 8 weeks using routine parameters such as hematological status, renal function, and serum PSA levels. For each patient, organ biodistribution in lesions, kidneys, liver, bone marrow, prostate, and whole body was calculated for both administration routes according to the Medical Internal Radiation Dose (MIRD) schema. Mean absorbed doses (MAD) across all patients were compared between both administration routes. ResultsThe MAD of all metastatic lesions was significantly higher by IA vs IV administration (1.59 vs 1.20 MGy/MBq; p=0.024). The prostate gland had a lower MAD between IA and IV administrations, but the difference was not significant (0.27 vs 0.36 MGy/MBq; p=0.22). Patients tolerated IA administration very well without unexpected side effects. ConclusionThese preliminary results of an ongoing study showed that IA 177Lu-PSMA therapy is feasible and safe to treat metastatic lesions, potentially having a higher delivery efficacy compared to IV administration.This study is approved by Cerrahpasa Medical Faculty ethics committee on March 5, 2019 and retrospectively registered with file no: 83045809-604.01.02.