Dr Madan on Enzalutamide Monotherapy in Biochemically Recurrent Prostate Cancer

“These are some of the first data, certainly in [patients with] BCR [prostate cancer], that are looking at PSMA scans after treatment and basically successful PSA responses. These data are from the first 13 patients and are not looking at just any finding on PSA, they are specifically looking at tumor volume.”

Ravi A. Madan, MD, a senior clinician in the Genitourinary Malignancies Branch at the National Cancer Institute (NCI), discussed findings from a phase 2 trial (NCT06096870) of enzalutamide (Xtandi) monotherapy for the treatment of patients with biochemically recurrent (BCR) prostate cancer, which were presented in a poster during the 2026 Genitourinary Cancers Symposium.

The phase 2 trial was conducted at the NCI and randomly assigned patients (n = 50) to receive either enzalutamide monotherapy or enzalutamide in combination with the IL-12 immunocytokine PDS01ADC. The combination arm was not fully accrued at the data cutoff, Madan noted; the poster presentation included data from the first 13 patients in the combination arm.

Findings from the study revealed that 4 of 13 patients experienced a 100% decline in prostate-specific antigen (PSA) levels after 3 months of therapy. Moreover, the median PSA response was –98% (range, –88% to –100%) and the median PSA control below baseline was 266 days (range, 210-371). However, findings in terms of changes in PSMA tumor volume after 3 months of treatment indicated that enzalutamide monotherapy did not provide clinical benefit, Madan noted.

Madan explained that these are some of the first data in BCR prostate cancer to demonstrate successful PSA responses that also examined PSMA scans after treatment. The study authors wrote that their findings underscore the need for caution in the use of PSMA imaging presumptively to define therapeutic benefit in practice, unless additional data that better define treatment failure using this imaging modality become available.