Pooled analysis of early-phase studies of zanidatamab for unresectable locally advanced or metastatic HER2-positive salivary gland cancer

HER2 overexpression occurs in various subtypes of salivary gland cancers (SGCs) and can be associated with treatment challenges and poor clinical outcomes. Zanidatamab is a dual HER2-targeted, bispecific antibody. Pooled analysis of three early-phase trials evaluated zanidatamab for unresectable locally advanced or metastatic (LA/M) HER2-positive SGC. The analysis included 10 patients; 6 were previously treated with HER2-targeted therapy. Among 9 patients who received zanidatamab monotherapy, 7 experienced treatment-related adverse event (all grade 1 or 2). The confirmed objective response rate was 44% (95% CI 14-79), the median progression-free survival was 10.1 months (3.8-NE), and the median duration of response was not reached (9.4-42.3+ months). All patients experienced a reduction in tumor size. One patient who received zanidatamab plus evorpacept had a confirmed partial response and 18.4 months of progression-free survival. The authors conclude that, although the sample size is small, these findings support the use of zanidatamab for HER2-positive SGC.