GU Symposium 2021: Results From the Biomarker Cohort of the Phase III SPARTAN Trial
Posted: Tuesday, February 16, 2021
In the phase III SPARTAN trial, apalutamide plus androgen-deprivation therapy seemed to significantly improve metastasis-free survival compared with the placebo plus androgen-deprivation therapy in patients with nonmetastatic castration-resistant prostate cancer. Felix Y. Feng, MD, of the University of California, San Francisco, and colleagues conducted an exploratory analysis to investigate the potential biologic signatures of patients with long-term responses to either of these treatment methods. The results from the biomarker cohort were presented during the virtual edition of the 2021 Genitourinary (GU) Cancers Symposium (Abstract 8).
“These molecular determinants may have utility in selecting patients with nonmetastatic castration-resistant prostate cancer who may derive the most benefit from apalutamide and other androgen signaling inhibitors,” the investigators concluded.
Based on the time to metastasis, patients were characterized as either long-term responders or early progressors; they were subsequently separated into quartiles. Patients who experienced disease progression in the first quartile (apalutamide: n = 21; placebo: n = 17) were classified as early progressors. Those who experienced disease progression in the last quartile (apalutamide: n = 39; placebo: n = 20) were classified as long-term responders.
In the long-term responders, the median time to metastatic disease progression was 40.5 months with apalutamide and 22 months with the placebo. In the early progressors, the median time to metastatic disease progression was longer with apalutamide than with the placebo (7.3 vs. 3.6 months, respectively).
The signatures were categorized into three general mechanistic classes: immune regulation, proliferation, and hormone dependence. They seemed to be associated with long-term responses after treatment with apalutamide and included increased T-cell activity reflected by T-cell activation, stimulation, cytokine response, interferon production, decreased T-cell exclusion, low proliferative capacity, and increased hormonal dependence. High-risk, hormone-nonresponsive, and neuroendocrine-like tumors appeared to be associated with early disease progression in patients treated with the placebo.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.