Efficacy of S-1 Monotherapy for Salivary Duct Carcinoma With MYC Amplification.
Hirotaka Suto, Miyuki Kawamura, Mitsunori Morita et al.
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Case in brief
A 70-year-old man with HER2-positive, androgen receptor-positive submandibular salivary duct carcinoma presented with multiple lung metastases. His disease progressed after trastuzumab plus docetaxel, platinum-based chemotherapy, and androgen-deprivation therapy. Genomic profiling identified ERBB2 and MYC amplifications. After starting late-line S-1 monotherapy, imaging at 2 months showed shrinkage of lung and liver metastases, and disease control persisted for more than 5 months.
What made this case unusual
S-1 monotherapy showed disease control after progression on anti-HER2 therapy, platinum-based chemotherapy, and androgen-deprivation therapy in a tumour with MYC amplification.
Diagnostic / clinical pearl
In this case, genomic profiling identified MYC amplification, and S-1 monotherapy was associated with metastatic tumour shrinkage after several prior systemic treatments had failed.
Why it matters
The report suggests S-1 may be a treatment option in advanced salivary duct carcinoma refractory to these therapies, particularly when MYC amplification is present; efficacy and predictive value are not established by this single case.