AUA 2018: Clinical Experience with Lutetium 177-labeled PSMA-I&T for Radioligand Therapy in Patients with Metastatic Castration-resistant Prostate Cancer

San Francisco, CA ( Matthias Heck, MD from Munich, Germany presented clinical experience with Lutetium 177-labeled PSMA ligand for systemic radioligand therapy in 100 patients with metastatic castration-resistant prostate cancer. PSMA is a prostate-specific membrane antigen transmembrane protein that gets overexpressed in prostate cancer.  The expression is directly related to a higher grade or castration-resistant tumors, or metastatic disease.  The goal of this study was to report long-term outcomes, focusing on activity, toxicity, and subgroup analysis. 

Patients were included if they had previous treatment with abiraterone or enzalutamide, or previous taxane-based chemotherapy or determined to be taxane ineligible.  Patients also needed to have a positive Galium 68 PSMA tracer uptake in metastasis on a baseline PET scan.  Intravenous administration of 177Lu-PSMA was given at 6- to 8- weekly with an activity of 7.4 GBq.  Up to 6 cycles were administered in patients without clinical or radiographic expression. 

Median age was 72 years with a median PSA of 165 ng/ml.  82 of the patients had received previous docetaxel therapy with over half having greater than 3 previous systemic therapies.  Metastatic sites included:  87 patients with nodal disease, 96 patients with bone disease, and 35 with visceral metastasis.   

Most common adverse events were grade 1-2 and they included anemia, dry mouth, and fatigue.  Most common grade 3-4 toxicities were anemia and neutropenia.  PSA decline >30% was seen in approximately half of the patients and >50% in 38 patients.  Median clinical progression-free and overall survival was 4.1 months and 12.9 months, respectively. Multivariate subgroup analysis demonstrated a progression-free survival in patients without visceral metastasis of 5.9 months compared to 3.1 months in patients with visceral metastasis (p=0.007).  Additionally, overall survival in these cohorts were 14.0 months versus 8.0 months (p=0.03). 

In conclusion, 177 Lu-PSMA appears to be safe and active in patients with previous systemic treatments and metastatic castration-resistant prostate cancer.   It has a low and acceptable toxicity profile with PSA response.  Future prospective trials are needed to evaluate this novel therapy. 

Presented by: Matthias Heck, MD, Technical University of Munich, Germany
Co-Authors: Sebastian Schwaiger, Karina Knorr, Margitta Retz, Tobias Maurer, Friederike Janssen, Calogero D`Alessandria, Munich, Germany, Hans-Jürgen Wester, Gauting, Germany, Jürgen Gschwend, Markus Schwaiger, Robert Tauber, Matthias Eiber, Munich, Germany

Written by:  David B. Cahn, DO, MBS Fox Chase Cancer Center Philadelphia, PA, @dbcahn at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA

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