Enzalutamide Treatment for Prostate Cancer: Still Beneficial After Disease Progression?
Posted: Thursday, October 22, 2020
Patients with progressive metastatic castration-resistant prostate cancer may continue to benefit from enzalutamide treatment even beyond disease progression, according to Glenn Liu, MD, of the University of Wisconsin Carbone Cancer Center, and colleagues. The researchers also suggested that early spatial-temporal response assessment could individualize treatment by stratifying patients into optimal versus suboptimal response groups. These results from this phase II, open-label, multicenter, single-arm study were published in the Journal of Clinical Oncology.
“At the time of disease progression, some individuals may have oligoprogressive disease, which may be salvaged with targeted ablation of progressing lesions, whereas systemic progression would suggest a change in therapy,” the study authors stated. “Our study highlights that treatment benefit is not a binary measure.”
A total of 23 men with progressive metastatic castration-resistant prostate cancer and at least 2 lesions on bone scintigraphy were enrolled. Patients were treated daily with 160 mg of enzalutamide. The dosage was reduced if enzalutamide-associated toxicity reached grade 3 or higher. Fluorothymidine F 18 (FLT) PET/CT scans were obtained at baseline, 13 weeks into treatment, and at 2 years without disease progression; they also were obtained at the time of prostate-specific antigen (PSA), radiographic, or clinical disease progression. The duration of treatment ranged from 1.4 to 13.4 months.
Global standardized uptake value (SUV) metrics were decreased 13 weeks after enzalutamide treatment but increased with progression of the disease. Alterations in SUVhetero (heterogeneity of FLT uptake) accounted for the majority of PSA increases (hazard ratio = 3.88; 95% confidence interval = 1.24–12.1). Although overall functional disease burden was improved during treatment, there was an increase in total SUV burden at the time of disease progression. However, all men who exhibited disease progression had at least one bone lesion still responding to treatment at the final time point.
Disclosure: For full disclosures of study authors, see ascopubs.org.