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HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial

ABSTRACT: HER2-targeted therapies including antibody drug conjugates have shown great efficacy in HER2-positive breast cancer. However, resistance to treatment in part due to pre-existing HER2 heterogeneity (HET) is a significant clinical challenge and requires the use of rationally-designed combination therapies. Here we describe transcriptomic profiling of 287 biopsies from 129 patients in a phase II neoadjuvant clinical trial using a combination of T-DM1 and pertuzumab for early-stage HER2-positive breast cancer, we investigated the mechanisms driving T-DM1 resistance. In pre-treatment tumors from patients without a complete response (pCR), distinct molecular features were identified: HER2 HET tumors retained PI3K pathway activation and a basal-like phenotype, while HER2 Non-HET tumors exhibited lower PI3K pathway enrichment. T-DM1 treatment universally reduced HER2 protein expression and copy number heterogeneity while increasing PI3K pathway enrichment and luminal identity in residual tumors. Importantly, HER2 HET tumors showed minimal transcriptomic response compared to HER2 Non-HET tumors, in line with the lesser clinical response. The response to T-DM1 was not associated with hotspot PIK3CA/ERBB2 mutations but rather correlated with immune infiltration. HER2 Non-HET tumors exhibited less effective immune surveillance at baseline but became immune activated with T-DM1 treatment, while HER2 HET tumors exhibited a more immune suppressed microenvironment upon treatment. Our study highlights the multifaceted nature of T-DM1 resistance driven by HER2 heterogeneity and provides essential evidence for optimizing therapeutic strategies for these patients.

ORGANISM(S): Homo sapiens

PROVIDER: GSE243375 | GEO | 2024/02/29

REPOSITORIES: GEO

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Project description:No targeted treatments are currently approved for HER2 exon 20 insertion-mutant lung adenocarcinoma patients. Mobocertinib (TAK-788) is a potent irreversible tyrosine kinase inhibitor (TKI) designed to target human epidermal growth factor receptor 2 (HER2/ERBB2) exon 20 insertion mutations. However, the function of mobocertinib on HER2 exon 20 insertion-mutant lung cancer is still unclear. Here we conducted systematic characterization of preclinical models to understand the activity profile of mobocertinib against HER2 exon 20 insertions. In HER2 exon 20 insertion-mutant cell lines, the IC50 of mobocertinib was higher than poziotinib and comparable with or slightly lower than afatinib, neratinib, and pyrotinib. Mobocertinib had the lowest HER2 exon 20 insertion IC50/wild-type (WT) EGFR IC50 ratio, indicating that mobocertinib displayed the best selectivity profile in these models. Also, mobocertinib showed strong inhibitory activity in HER2 exon 20YVMA allograft and patient-derived xenograft models. In genetically engineered mouse models, HER2 exon 20G776>VC lung tumors exhibited a sustained complete response to mobocertinib, whereas HER2 exon 20YVMA tumors showed only partial and transient response. Combined treatment with a second antibody-drug conjugate (ADC) against HER2, ado-trastuzumab emtansine (T-DM1), synergized with mobocertinib in HER2 exon 20YVMA tumors. In addition to the tumor cell autonomous effect, sustained tumor growth control derived from M1 macrophage infiltration and CD4+ T-cell activation. These findings support the ongoing clinical development of mobocertinib (NCT02716116) and provide a rationale for future clinical evaluation of T-DM1 combinational therapy in HER2 exon 20YVMA insertion-mutant lung adenocarcinoma patients. SIGNIFICANCE: This study elucidates the potent inhibitory activity of mobocertinib against HER2 exon 20 insertion-mutant lung cancer and the synergic effect of combined mobocertinib and T-DM1, providing a strong rationale for clinical investigation.

Project description:Purpose HER2 gene amplification or protein overexpression (HER2+) defines a clinically challenging subgroup of breast cancer with variable prognosis and response to therapy. We aimed to investigate the heterogeneous biological appearance and clinical behavior of HER2+ tumors using molecular profiling. Materials and Methods Hierarchical clustering of gene expression data from 58 HER2-amplified tumors of various stage, histological grade and estrogen receptor (ER) status was used to construct a HER2-derived prognostic predictor that was further evaluated in several large independent breast cancer data sets. Results Unsupervised analysis identified three subtypes of HER2+ tumors with mixed stage, histological grade and ER-status. One subtype had a significantly worse clinical outcome. A prognostic predictor was created based on differentially expressed genes between the subtype with worse outcome and the other subtypes. The predictor was able to define patient groups with better and worse outcome in HER2+ breast cancer across multiple independent breast cancer data sets and identify a sizable HER2+ group with long disease-free survival and low mortality. Significant correlation to prognosis was also observed in basal-like, ER−, lymph node positive or high-grade tumors, irrespective of HER2-status. The predictor included genes associated to immune response, tumor invasion and metastasis. Conclusion The HER2-derived prognostic predictor provides further insight into the heterogeneous biology of HER2+ tumors and may become useful for improved selection of patients that need additional treatment with new drugs targeting the HER2 pathway. Array comparative genomic hybridization (aCGH) identified 58 breast tumors with amplification of HER2 from a larger cohort of approx 500 tumors breast. Global gene expression profiles were obtained using 70-mer oligonucleotide microarrays. Unsupervised hierarchical clustering of the 58 tumors, using Pearson correlation and complete linkage, identified three main clusters. One cluster showed significantly poorer clinical outcome. Significance of microarray (SAM) analysis was performed to identify 158 genes separating the poor outcome cluster compared to the other two clusters. Gene expression centroids, based on the 158 genes, were created for each cluster for validation in independent breast cancer data sets.

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HER2 heterogeneity and treatment response-associated profiles in HER2-positive breast cancer in the NCT02326974 clinical trial

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