Prostate-specific membrane antigen (PSMA) is overexpressed in
prostate cancer and even more so with castration-resistant disease. This
makes development of new tracers for PSMA-targeted radionuclide
therapies a promising treatment approach.
Prostate cancer deaths are
usually the result of metastatic castration-resistant prostate cancer
(mCRPC), and the median survival for men with mCRPC
has been less than two years.
‘Lutetium-177 (Lu-177)-labeled PSMA-617 is a promising new therapeutic agent for radioligand therapy (RLT) of patients with metastatic castration-resistant prostate cancer.’
A German multicenter study, initiated by the German Society of
Nuclear Medicine, demonstrates that lutetium-177 (Lu-177)-labeled
PSMA-617 is a promising new therapeutic agent for radioligand therapy
(RLT) of patients with metastatic castration-resistant prostate cancer.
The study is published in the January 2017 issue of the Journal of Nuclear Medicine
and is the featured article.
"Previous studies with small number of patients have indicated the
high potential of this new therapeutic option," explains Kambiz Rahbar,
University Hospital Muenster. "This study of a large number of
patients at multiple healthcare facilities, however, confirms the
efficacy and safety of Lu-177-PSMA-617 radioligand therapy."
At 12 therapy centers across Germany, 145 patients (median age 73
years, range 43-88) with mCRPC were treated with Lu-177-PSMA-617 between
February 2014 and July 2015 with one to four therapy cycles. A total of
248 therapy cycles were performed in 145 patients.
Efficacy was defined
by a prostate-specific antigen (PSA) decline of 50% or more from
baseline to at least two weeks after start of RLT. Overall, 45%
of patients had a positive response following all therapy cycles, while
40% responded after a single cycle.
Some adverse side effects were noted but manageable. Hematotoxicity
occurred in 18 patients: 10% experienced anemia; 4%,
thrombocytopenia (low platelet count); and 3%, leukopenia (low
white blood cell count). Dry mouth was experienced by 8%.
The study shows that Lu-177-PSMA-617 radioligand therapy is safe and
more effective than other third-line systemic therapies for mCRPC
patients. Future Phase II and III studies are needed to clarify the
survival benefit of this new therapy, which is not yet FDA-approved.
"This therapeutic will provide an additional therapy option for
end-stage metastasized, heavily pretreated prostate cancer patients,"
said Rahbar. "While already demonstrating remarkably high response rates
and low toxicity, in the future it may be available at earlier stages
of disease with even higher response rates and lower toxicity."