OBJECTIVES

The study objective was to describe rwOS by HER2 expression level for patients with advanced/metastatic (a/m) head and neck squamous cell (HNSCC), ovarian (OC), endometrial (EC), or non-small cell lung cancer (NSCLC) receiving first-line (1L) treatment.

METHODS

This retrospective analysis of the Tempus database included adults diagnosed with a/m HNSCC, EC, OC, or NSCLC between 2015-2021, who received 1L treatment, and had NGS testing ≤90 days of a/m diagnosis. Index date was defined as 1L treatment initiation date. Patients were followed until death, loss to follow-up, or 3 years post-index. Thresholds derived from logistic regression models of HER2 IHC/ISH and ERBB2 mRNA expression by NGS in tumor samples of patients with a/m breast (BC) or gastric cancer (GC) were applied to included tumor types to predict HER2 expression. Multivariable Cox proportional hazards models were fit for each cancer type using those thresholds. The outcome of interest was rwOS associated with HER2 mRNA expression levels (HER2 zero, low, positive).

RESULTS

3431 patients were included in the survival analyses (415 HNSCC; 528 OC; 199 EC; 2289 NSCLC). HER2 expression was prevalent across all solid tumors investigated. Median follow-up was 14.8 months (mo) in NSCLC, 16.1 mo in HNSCC, 16.3 mo in EC, and 20.4 mo in OC. In multivariable models, HER2 mRNA expression level (by BC or GC thresholds) did not predict survival in HNSCC, EC, or NSCLC. Regardless of BC or GC threshold, HER2+ was associated with worse survival vs HER2 zero in EC and OC.

CONCLUSIONS

HER2 expression was observed across investigated tumor types. While survival differences were observed based on HER2 mRNA expression levels, only OC preserved directionality correlating higher levels of HER2 with poorer rwOS, in multivariable models. Additional studies incorporating HER2 IHC/ISH testing will provide insight into the role of the HER2 pathway in solid tumors.

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