New Therapeutic Agent Identified for Advanced Prostate Cancer

Study confirms safety and efficacy of Lu-177-PSMA-17 radioligand therapy for metastatic castration-resistant prostate cancer.

Investigators have found a promising new therapeutic agent for radioligand therapy (RLT) in patients with metastatic castration-resistant prostate cancer (mCRPC).

In a study published in the Journal of Nuclear Medicine, the therapeutic agent lutetium-177 (Lu-177)-labeled PSMA-617 demonstrated superior efficacy compared with other third-line systemic therapies for mCRPC patients.

The study included 145 patients with mCRPC, aged 43 to 88 years, at 12 therapy centers across Germany. The participants were administered 1 to 4 therapy cycles with Lu-177-PSMA-17 between February 2014 and July 2015. In total, 248 therapy cycles were performed in 145 patients.

For the study, efficacy was defined by PSA decline of 50% or more from baseline to at least 2 weeks after start of RLT.

The results of the study showed that overall, 45% of patients had a positive response after all therapy cycles had finished, while 40% responded after a single cycle. Adverse effects reported were hematotoxicity, anemia, dry mouth, thrombocytopenia, and leukopenia.

“Previous studies with small number of patients have indicated the high potential of this new therapeutic option,” said investigator Kambiz Rahbar, MD. “This study of a large number of patients at multiple health care facilities, however, confirms the efficacy and safety of Lu-177-PSMA-17 radioligand therapy.”

Lu-177-PSMA-17 radioligand therapy had a higher efficacy compared with other third-line systemic therapies for mCRPC patients. The development of new tracers for prostate-specific membrane antigen (PSMA)-targeted radionuclide therapies are a promising approach, since PSMA is overexpressed in prostate cancer, particularly mCRPC.

The authors noted that phase 2 and 3 trials are needed to clarify the survival benefit of this new therapy, which has not yet received FDA approval.

“This therapeutic will provide an additional therapy option for end-stage metastasized, heavily pretreated prostate cancer patients,” Rahbar said. “While already demonstrating remarkably high response rates and low toxicity, in the future it may be available at earlier stages of disease with even high response rates and lower toxicity.”