Posted: Wednesday, May 24, 2023
Targeted radioligand therapy with lutetium-177–prostate-specific membrane antigen-617 (Lu-177–PSMA-617) is an efficacious treatment for patients with metastatic castration-resistant prostate carcinoma, whereas less is known about the outcomes and safety of 177-Lu–PSMA-I&T. (PSMA-617 contains a DOTA chelator, whereas PSMA-I&T contains a DOTAGA chelator.) In a recent study presented at the American Urological Association (AUA) Annual Meeting 2023 (Abstract MP11-07) and published in The Journal of Urology, 177-Lu–PSMA-I&T achieved a prostate-specific antigen (PSA) response (of at least 30%) in more than half of patients with metastatic castration-resistant prostate carcinoma. These findings were presented by Mehmet Onur Demirkol, MD, of Koc University Hospital, Istanbul, and colleagues.
A total of 33 patients with metastatic castration-resistant prostate cancer were recruited for the study. All patients received 88 cycles of Lu-177–PSMA-I&T. PSA levels were monitored throughout the treatment cycles. Patients also received regular imaging to assess any treatment-related changes.
The study authors observed a decline in PSA levels in 69% of patients. After radioligand therapy, 56% of patients achieved a PSA decline of at least 30%, and 34% of patients achieved a PSA decline of at least 50%. In addition, the overall survival and clinical progression-free survival were 21.4 months and 6.3 months, respectively. Furthermore, 12.4% of patients (n = 4) experienced radioligand therapy–related nephrotoxicity. Using the Common Toxicity Criteria for Adverse Events, the authors determined that the estimated glomerular filtration rate worsened from grade 1 to 2 in two patients, from grade 2 to 3 in one patient, and from grade 3 to 4 in one patient. Moreover, grade 1 or 2 myelotoxicity was observed in 18.2% of patients, and grade 3 or 4 myelotoxicity occurred in 9.1% of patients.
Despite its favorable toxicity profile and early efficacy, additional investigative efforts are warranted to fully elucidate its benefit in this patient population, according to the investigators.
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