Apalutamide and Goserelin for Androgen Receptor-Positive Salivary Gland Carcinoma: A Phase 2 Nonrandomized Clinical Trial, YATAGARASU.

To assess efficacy and safety of apalutamide plus goserelin for androgen receptor (AR)-positive, unresectable or recurrent/metastatic salivary gland carcinoma (URM-SGC). This was an open-label, single-arm, multicenter phase II study for patients with AR-positive URM-SGC. The primary endpoint was the overall response rate (ORR) by an independent central radiology review (ICRR) in the first 24 response evaluable 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. 31 patients were enrolled. In the first 24 primary RE patients with a median follow-up of 7.4 months, confirmed ORR by ICRR was 25.0% (6/24 patients; 95%CI: 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. 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 SGC and safety consistent with prior experience in prostate cancer.