The Clinical Utilisation and Duration of Treatment with HER2-Directed Therapies in HER2-Positive Recurrent or Metastatic Salivary Gland Cancers.

Salivary gland cancers (SGC) are rare tumours with limited availability of systemic therapies. Some SGC subtypes overexpress HER2, and this represents a potential therapeutic target, but the evidence base is limited. This study sought to analyse real-world data on the efficacy of HER2-directed therapies in SGC. This is a retrospective observational study using anonymised data from commercial compassionate-use access registrations and a privately funded pharmacy prescribing register. Treatment duration was defined as the time from drug initiation to treatment discontinuation. Kaplan-Meier analysis of treatment duration was performed using R for Windows (v4.3.2). A case report is also provided of an exceptional responder. Eighteen patients were identified who received HER2-directed therapies for HER2-positive recurrent/metastatic SGC, and complete data on treatment duration was available for 15/18. Histology was salivary duct carcinoma in 13/18 patients, adenocarcinoma NOS in 4/18, and carcinoma ex pleomorphic adenoma in 1/18. The median treatment duration was 8.3 months (95% CI: 6.41-not reached), and the range was 1.0-47.0 months. Choice of HER2-directed therapy varied, with ado-trastuzumab emtasine being the most common (9/18). At the time of analysis, HER2-directed therapy was ongoing for 9/15, discontinued due to disease progression for 4/15, discontinued due to toxicity for 1/15, and 1/15 was discontinued for an unspecified reason. An exceptional responder experienced a complete response with a treatment duration of 47.0 months. These real-world data are comparable to the median PFS observed with HER2-directed therapies in phase II trials and support the use of HER2-directed therapies in this group.

Clinical disease course and survival outcomes following disease recurrence in adenoid cystic carcinoma with and without NOTCH signaling pathway activation.

BACKGROUND: Adenoid cystic carcinoma (ACC) is a rare salivary cancer. The highest rates of disease recurrence are in patients with NOTCH pathway activation, reported in up to 20%. Novel drugs targeting NOTCH signaling are under investigation in the recurrent/metastatic (R/M) setting. To understand their clinical utility, there is an urgent need to better characterize the disease course and outcomes following current standard of care treatment. METHODS: 120 patients with R/M ACC underwent clinical review at a single UK Cancer Centre. Patients were retrospectively assessed for tumor NOTCH pathway activation using next generation sequencing (NGS) targeting NOTCH1/2/3 genes and/or NOTCH1 intra-cellular domain (NICD1) immunohistochemistry. Demographic and treatment data were extracted from the clinical notes. Kaplan-Meier survival analysis was performed using log rank test. RESULTS: NOTCH pathway activation was identified in 13/120 patients (11 %). In 12/101 patients analyzed by NGS, NOTCH1/3 activating somatic mutations were identified, and a further patient was identified with NICD1 diffuse nuclear staining in whom NGS testing was not possible. Patients with NOTCH pathway activation had shorter median RFS (1.1 vs 3.4 years, p = 0.2032) and significantly reduced median OS from diagnosis (4.0 vs 16.3 years, p < 0.0001). There was significantly reduced median OS from time of disease recurrence/metastasis (1.9 vs 9.6 years, p < 0.0001). CONCLUSION: This study clearly demonstrates a reduction in OS from time of first confirmed disease recurrence/metastasis for patients with NOTCH pathway activated ACC. This provides support for developing new drugs for this sub-group of patients, for whom clinical outcomes are significantly worse and effective treatments are lacking.