Durable response to bicalutamide, goserelin, and dutasteride for androgen receptor-positive metastatic salivary duct carcinoma: a case report

The DUCT study is a prospective, randomised, controlled phase II clinical trial investigating the efficacy of dutasteride, a steroid 5α-reductase inhibitor, added to standard-of-care bicalutamide and goserelin in patients with recurrent and/or metastatic (R/M) androgen receptor (AR)-positive salivary duct carcinoma (SDC). In cohort A, patients without prior androgen blockade therapy were randomly assigned (1 : 1) to receive bicalutamide plus goserelin (control arm) or bicalutamide, goserelin, and dutasteride (experimental arm). Assignment to cohort A was closed prematurely due to limited accrual. In this article, we describe a patient enrolled in the experimental arm who demonstrated a remarkable and durable response, including marked regression of the primary parotid tumour, a dural metastasis, and multiple bone lesions. At 132 weeks after treatment initiation, the response remains ongoing and side-effects have been mild. This case illustrates the potential efficacy of triple androgen blockade incorporating dutasteride for patients with R/M AR-positive SDC who have not previously received hormonal therapy.