Apalutamide and Goserelin for Androgen Receptor–Positive Salivary Gland Carcinoma: A Phase II Nonrandomized Clinical Trial, YATAGARASU

Abstract Purpose: To assess the efficacy and safety of apalutamide plus goserelin for androgen receptor (AR)–positive unresectable or recurrent/metastatic salivary gland carcinoma. Patients and Methods: This trial was an open-label, single-arm, multicenter phase II study. Patients with histologically confirmed unresectable or recurrent/metastatic salivary gland carcinoma with AR expression were included. The primary endpoint was the overall response rate (ORR) according to RECIST v1.1 by an independent central radiology review in the first 24 response-evaluable (RE) patients who had been observed at least 24 weeks from study initiation (primary RE patients). The efficacy was to be declared when at least 8 of the 24 primary RE patients responded. Results: A total of 31 patients were enrolled. In the first 24 primary RE patients with a median follow-up of 7.4 months, confirmed ORR by independent central radiology review was 25.0% [6/24 patients; 95% confidence interval, 9.8%–46.7%; P = 0.11 (one-sided)], which did not meet the predefined criteria of efficacy. Clinical benefit rate (ORR + rate of stable disease for at least 24 weeks) and median progression-free survival were 50.0% and 7.4 months, respectively. Both median duration of response and overall survival were not reached. Exploratory analyses showed a better ORR of 54.5% (6/11) in patients with AR positivity ≥70% and no history of prior systemic therapy. Grade 3 or higher treatment-emergent adverse events were reported in 35.5% (11/31), which included skin rash, anemia, leukopenia, and cancer pain. Conclusions: Although this study did not meet the predefined efficacy criteria, apalutamide plus goserelin showed clinically meaningful efficacy in a subset of patients with AR-positive salivary gland carcinoma and safety consistent with prior experience in prostate cancer.