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Blood-based monitoring identifies acquired and targetable driver HER2 mutations in endocrine-resistant metastatic breast cancer.

ABSTRACT: Plasma genotyping identifies potentially actionable mutations at variable mutant allele frequencies, often admixed with multiple subclonal variants, highlighting the need for their clinical and functional validation. We prospectively monitored plasma genotypes in 143 women with endocrine-resistant metastatic breast cancer (MBC), identifying multiple novel mutations including HER2 mutations (8.4%), albeit at different frequencies highlighting clinical heterogeneity. To evaluate functional significance, we established ex vivo culture from circulating tumor cells (CTCs) from a patient with HER2-mutant MBC, which revealed resistance to multiple targeted therapies including endocrine and CDK 4/6 inhibitors, but high sensitivity to neratinib (IC50: 0.018 μM). Immunoblotting analysis of the HER2-mutant CTC culture line revealed high levels of HER2 expression at baseline were suppressed by neratinib, which also abrogated downstream signaling, highlighting oncogenic dependency with HER2 mutation. Furthermore, treatment of an index patient with HER2-mutant MBC with the irreversible HER2 inhibitor neratinib resulted in significant clinical response, with complete molecular resolution of two distinct clonal HER2 mutations, with persistence of other passenger subclones, confirming HER2 alteration as a driver mutation. Thus, driver HER2 mutant alleles that emerge during blood-based monitoring of endocrine-resistant MBC confer novel therapeutic vulnerability, and ex vivo expansion of viable CTCs from the blood circulation may broadly complement plasma-based mutational analysis in MBC.

SUBMITTER: Medford AJ

PROVIDER: S-EPMC6635494 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Blood-based monitoring identifies acquired and targetable driver <i>HER2</i> mutations in endocrine-resistant metastatic breast cancer.

Medford Arielle J AJ Dubash Taronish D TD Juric Dejan D Spring Laura L Niemierko Andrzej A Vidula Neelima N Peppercorn Jeffrey J Isakoff Steven S Reeves Brittany A BA LiCausi Joseph A JA Wesley Benjamin B Malvarosa Giuliana G Yuen Megan M Wittner Ben S BS Lawrence Michael S MS Iafrate A John AJ Ellisen Leif L Moy Beverly B Toner Mehmet M Maheswaran Shyamala S Haber Daniel A DA Bardia Aditya A

NPJ precision oncology 20190716

Plasma genotyping identifies potentially actionable mutations at variable mutant allele frequencies, often admixed with multiple subclonal variants, highlighting the need for their clinical and functional validation. We prospectively monitored plasma genotypes in 143 women with endocrine-resistant metastatic breast cancer (MBC), identifying multiple novel mutations including <i>HER2</i> mutations (8.4%), albeit at different frequencies highlighting clinical heterogeneity. To evaluate functional ...[more]

PMID: 31341951

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Project description:BackgroundEvolutionary models of breast cancer progression differ on the extent to which metastatic potential is pre-encoded within primary tumors. Although metastatic recurrences often harbor putative driver mutations that are not detected in their antecedent primary tumor using standard sequencing technologies, whether these mutations were acquired before or after dissemination remains unclear.MethodsTo ascertain whether putative metastatic driver mutations initially deemed specific to the metastasis by whole exome sequencing were, in actuality, present within rare ancestral subclones of the primary tumors from which they arose, we employed error-controlled ultra-deep sequencing (UDS-UMI) coupled with FFPE artifact mitigation by uracil-DNA glycosylase (UDG) to assess the presence of 132 "metastasis-specific" mutations within antecedent primary tumors from 21 patients. Maximum mutation detection sensitivity was ~1% of primary tumor cells. A conceptual framework was developed to estimate relative likelihoods of alternative models of mutation acquisition.ResultsThe ancestral primary tumor subclone responsible for seeding the metastasis was identified in 29% of patients, implicating several putative drivers in metastatic seeding including LRP5 A65V and PEAK1 K140Q. Despite this, 93% of metastasis-specific mutations in putative metastatic driver genes remained undetected within primary tumors, as did 96% of metastasis-specific mutations in known breast cancer drivers, including ERRB2 V777L, ESR1 D538G, and AKT1 D323H. Strikingly, even in those cases in which the rare ancestral subclone was identified, 87% of metastasis-specific putative driver mutations remained undetected. Modeling indicated that the sequential acquisition of multiple metastasis-specific driver or passenger mutations within the same rare subclonal lineage of the primary tumor was highly improbable.ConclusionsOur results strongly suggest that metastatic driver mutations are sequentially acquired and selected within the same clonal lineage both before, but more commonly after, dissemination from the primary tumor, and that these mutations are biologically consequential. Despite inherent limitations in sampling archival primary tumors, our findings indicate that tumor cells in most patients continue to undergo clinically relevant genomic evolution after their dissemination from the primary tumor. This provides further evidence that metastatic recurrence is a multi-step, mutation-driven process that extends beyond primary tumor dissemination and underscores the importance of longitudinal tumor assessment to help guide clinical decisions.

Project description:BackgroundGiven advancements in adjuvant treatments for non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK)-targeted therapies, it is important to consider postoperative targeted therapies for other early-stage oncogene-addicted NSCLC. Exploring baseline outcomes for early-stage NSCLC with these rare mutations is crucial.ObjectivesThis study aims to assess relapse-free survival (RFS) and overall survival (OS) in patients with resected early-stage NSCLC with rare targetable driver mutations.MethodsThis retrospective single-center study identified stage I-III NSCLC patients with rare targetable mutations who underwent curative surgery. Tissue-based molecular profiling identified mutations in KRASG12C, EGFR Exon20, Erb-B2 receptor tyrosine kinase 2 (ERBB2), ALK, ROS1, B-Raf proto-oncogene (BRAF) V600E, mesenchymal-epithelial transition factor (MET) exon14 skipping, and rearranged during transfection (RET). Baseline patient and tumor characteristics, mutation subtype, and TP53 co-mutation were correlated with RFS and OS using Cox regression. The KRASG12C cohort was used as the reference for survival comparisons.ResultsAmong 225 patients, mutations included the following: KRASG12C (n = 101, 45%), MET exon 14 skipping (n = 26, 12%), EGFR Exon 20 (n = 25, 11%), ERBB2 (n = 25, 11%), ALK fusion (n = 16, 7%), ROS1 fusion (n = 14, 6%), BRAF V600E mutation (n = 13, 6%), and RET fusion (n = 5, 2%). Five-year survival probabilities were 76% for stage I, 60% for stage II, and 58% for stage III. RFS was shorter across most mutation subgroups compared to KRASG12C, with ROS1 mutations showing significantly poorer RFS (HR 2.70, p = 0.019). By contrast, all mutation subgroups were associated with better OS than KRASG12C. The incidence of brain metastasis was highest in ERBB2 (22% at 5 years). TP53 co-mutation was associated with significantly worse OS (HR 2.35, p = 0.008).ConclusionWhile RFS was poorer for most mutations compared to KRASG12C, OS generally was better, suggesting a potential role for postoperative targeted therapies. These findings warrant further investigation through prospective studies and clinical trials to optimize adjuvant treatment strategies for patients with early-stage NSCLC harboring rare driver mutations.

Dataset Information

Blood-based monitoring identifies acquired and targetable driver HER2 mutations in endocrine-resistant metastatic breast cancer.

Publications

Blood-based monitoring identifies acquired and targetable driver <i>HER2</i> mutations in endocrine-resistant metastatic breast cancer.

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