Predicting hematologic toxicity of lutetium-177 prostate-specific membrane antigen therapy in metastatic castration-resistant prostate cancer using pretreatment gallium-68 prostate-specific membrane antigen positron emission tomography imaging: preliminary data in Asian patients.

BACKGROUND: Lutetium-177 (Lu-177) prostate-specific membrane antigen (PSMA) therapy is an emerging treatment for metastatic castration-resistant prostate cancer (mCRPC), but there is limited evidence on whether imaging can predict treatment-related toxicity. This study investigated whether pretreatment PSMA PET imaging parameters could forecast toxicity and outcomes in Asian patients undergoing Lu-177 PSMA therapy.

PATIENTS AND METHODS: In this retrospective analysis, men with mCRPC treated with Lu-177 PSMA-617 at Koo Foundation Sun Yat-Sen Cancer Center, Taipei, were reviewed. Baseline Ga-68 PSMA-11 PET imaging metrics - including standardized uptake values (SUV), total lesion PSMA (TLP), and total tumor volume (TTV) - were assessed. Treatment response was measured by prostate-specific antigen (PSA) decline, and adverse effects and survival were evaluated from clinical records.

RESULTS: Eighteen men (median age: 75, range: 55-91) received a median of 2 (range: 1-6) cycles of Lu-177 PSMA therapy, with a mean administered radioactivity of 7.0 GBq (range: 3.0-7.4 GBq) per cycle. Grade 3/4 hematologic toxicities occurred in six (33.3%) patients, with thrombocytopenia (27.8%) and anemia (22.2%) most common. Higher TLP and TTV were linked to increased toxicity and poorer survival, while higher SUV mean was associated with better PSA response.

CONCLUSION: Pretreatment PSMA PET imaging may help predict adverse effects in Asian mCRPC patients undergoing Lu-177 PSMA therapy. Larger, prospective studies are needed for confirmation.