Radiolabeled prostate-specific membrane antigen (PSMA) ligands represent a true theranostic concept for diagnosis and therapy in patients with relapsed or metastatic prostate cancer. The aim of this study was to evaluate the response to and tolerability of a single dose of (177)Lu-PSMA-617 in a large cohort of patients with metastatic castration-resistant prostate cancer (mCRPC).
Methods: The data of 82 consecutive patients (median age, 73 y; range, 43-87 y) with mCRPC who received a single dose of (177)Lu-PSMA-617 (mean, 5.9 ± 0.5 GBq) were retrospectively analyzed. Data were collected at baseline and 8 wk after therapy. (68)Ga-PSMA-11 PET/CT was performed on all patients to verify sufficient PSMA expression. Bone, lymph node, liver, and lung metastases were present in 99%, 65%, 17%, and 11% of the patients, respectively. Tolerability and response were evaluated using hematologic parameters, renal scintigraphy, clinical data, and the prostate-specific antigen (PSA) level at baseline and 8 wk after therapy application.
Results: Six patients died, and 2 patients dropped out because they were not willing to continue therapy and follow-up. The complete dataset of 74 patients was available for analysis. Forty-seven patients (64%) showed a PSA decline, including 23 (31%) with a decline by more than 50%. Thirty-five patients (47%) had stable disease: the change in their PSA level ranged from less than a 50% decline to less than a 25% rise. Seventeen patients (23%) had progressive disease: their PSA level rose by more than 25%. There were no significant changes in hemoglobin, white blood cells, creatinine, or tubular extraction rates indicative of toxicity. There was a significant but mild decrease in platelets, but the median value was still within the reference range.
Conclusion: This retrospective multicenter analysis suggests that radioligand therapy with (177)Lu-PSMA-617 is safe and well tolerated and has a considerable effect on PSA level. Therefore, it offers an additional therapeutic option for patients with mCRPC. These data may justify further prospective randomized studies to evaluate and prove the clinical benefit in terms of survival and quality of life.
Keywords: 177Lu-PSMA; mCRPC; prostate cancer; radioligand therapy.
© 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.