Darolutamide Alone and in Combination With Goserelin in Androgen Receptor–Positive Salivary Gland Carcinoma: Results From the Phase II DISCOVARY Trial

Abstract

PURPOSE Salivary gland carcinoma (SGC), particularly salivary duct carcinoma (SDC), is a rare and aggressive malignancy with no standard systemic treatment. Androgen receptor (AR) expression is frequently detected in SDC, which suggests inhibition of the AR pathway as a therapeutic strategy. We conducted a prospective phase II trial of the efficacy and safety of darolutamide, a second-generation AR signaling inhibitor, as monotherapy or in combination with goserelin, in patients with AR-positive unresectable locally advanced (LA) or recurrent/metastatic (R/M) SGC. METHODS DISCOVARY was a multicenter, single-arm, phase II trial conducted in Japan. Patients with unresectable LA or R/M AR-positive SGC were enrolled into two sequential cohorts, a monotherapy cohort (darolutamide 600 mg orally twice daily) and a combination cohort (darolutamide plus goserelin 3.6 mg subcutaneously once every 28 days). The primary end point was objective response rate (ORR). Secondary end points included progression-free survival (PFS), overall survival (OS), safety, and health-related quality of life. RESULTS Fifty-seven patients were enrolled (monotherapy, n = 24; combination, n = 33). In the monotherapy cohort, the confirmed ORR was 8.3% (90% CI, 1.5 to 24.0) and the median PFS was 5.7 months. In the combination cohort, ORR was 45.2% (90% CI, 29.7 to 61.3) and the median PFS was 13.1 months. Twelve-month OS rates were 91.3% and 87.0%, respectively. Most adverse events were grade 1 or 2 in severity, with no treatment-related deaths. Quality of life was preserved. No clear association between AR expression level or Ki-67 index and treatment response was evident in exploratory analysis. CONCLUSION Darolutamide demonstrated antitumor activity in AR-positive SGC, with numerically more favorable outcomes with goserelin. Darolutamide plus goserelin may represent a chemotherapy-sparing option in this rare malignancy.