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HER2-Overexpressing Breast Cancers Amplify FGFR Signaling upon Acquisition of Resistance to Dual Therapeutic Blockade of HER2.

ABSTRACT: Purpose: Dual blockade of HER2 with trastuzumab and lapatinib or pertuzumab has been shown to be superior to single-agent trastuzumab. However, a significant fraction of HER2-overexpressing (HER2+) breast cancers escape from these drug combinations. In this study, we sought to discover the mechanisms of acquired resistance to the combination of lapatinib + trastuzumab.Experimental Design: HER2+ BT474 xenografts were treated with lapatinib + trastuzumab long-term until resistance developed. Potential mechanisms of acquired resistance were evaluated in lapatinib + trastuzumab-resistant (LTR) tumors by targeted capture next-generation sequencing. In vitro experiments were performed to corroborate these findings, and a novel drug combination was tested against LTR xenografts. Gene expression and copy-number analyses were performed to corroborate our findings in clinical samples.Results: LTR tumors exhibited an increase in FGF3/4/19 copy number, together with an increase in FGFR phosphorylation, marked stromal changes in the tumor microenvironment, and reduced tumor uptake of lapatinib. Stimulation of BT474 cells with FGF4 promoted resistance to lapatinib + trastuzumab in vitro Treatment with FGFR tyrosine kinase inhibitors reversed these changes and overcame resistance to lapatinib + trastuzumab. High expression of FGFR1 correlated with a statistically shorter progression-free survival in patients with HER2+ early breast cancer treated with adjuvant trastuzumab. Finally, FGFR1 and/or FGF3 gene amplification correlated with a lower pathologic complete response in patients with HER2+ early breast cancer treated with neoadjuvant anti-HER2 therapy.Conclusions: Amplification of FGFR signaling promotes resistance to HER2 inhibition, which can be diminished by the combination of HER2 and FGFR inhibitors. Clin Cancer Res; 23(15); 4323-34. ©2017 AACR.

SUBMITTER: Hanker AB

PROVIDER: S-EPMC5540793 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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HER2-Overexpressing Breast Cancers Amplify FGFR Signaling upon Acquisition of Resistance to Dual Therapeutic Blockade of HER2.

Hanker Ariella B AB Garrett Joan T JT Estrada Mónica Valeria MV Moore Preston D PD Ericsson Paula González PG Koch James P JP Langley Emma E Singh Sharat S Kim Phillip S PS Frampton Garrett M GM Sanford Eric E Owens Philip P Becker Jennifer J Groseclose M Reid MR Castellino Stephen S Joensuu Heikki H Huober Jens J Brase Jan C JC Majjaj Samira S Brohée Sylvain S Venet David D Brown David D Baselga José J Piccart Martine M Sotiriou Christos C Arteaga Carlos L CL

Clinical cancer research : an official journal of the American Association for Cancer Research 20170405 15

Purpose: Dual blockade of HER2 with trastuzumab and lapatinib or pertuzumab has been shown to be superior to single-agent trastuzumab. However, a significant fraction of HER2-overexpressing (HER2+) breast cancers escape from these drug combinations. In this study, we sought to discover the mechanisms of acquired resistance to the combination of lapatinib + trastuzumab.Experimental Design: HER2+ BT474 xenografts were treated with lapatinib + trastuzumab long-te ...[more]

PMID: 28381415

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Project description:IntroductionThe clinical prognosis of the HER2-overexpressing (HER2-OE) subtype of breast cancer (BC) is influenced by the immune infiltrate of the tumor. Specifically, monocytic cells, which are promoters of pro-tumoral immunosuppression, and NK cells, whose basal cytotoxic function may be enhanced with therapeutic antibodies. One of the standards of care for HER2+ BC patients includes the combination of the anti-HER2 antibodies trastuzumab and pertuzumab. This dual combination was a breakthrough against trastuzumab resistance; however, this regimen does not yield complete clinical benefit for a large fraction of patients. Further therapy refinement is still hampered by the lack of knowledge on the immune mechanism of action of this antibody-based dual HER2 blockade.MethodsTo explore how the dual antibody challenge influences the phenotype and function of immune cells infiltrating the HER2-OE BC microenvironment, we developed in vitro 3D heterotypic cell models of this subtype. The models comprised aggregates of HER2+ BC cell lines and human peripheral blood mononuclear cells. Cells were co-encapsulated in a chemically inert alginate hydrogel and maintained in agitation-based culture system for up to 7 days.ResultsThe 3D models of the HER2-OE immune microenvironment retained original BC molecular features; the preservation of the NK cell compartment was achieved upon optimization of culture time and cytokine supplementation. Challenging the models with the standard-of-care combination of trastuzumab and pertuzumab resulted in enhanced immune cytotoxicity compared with trastuzumab alone. Features of the response to therapy within the immune tumor microenvironment were recapitulated, including induction of an immune effector state with NK cell activation, enhanced cell apoptosis and decline of immunosuppressive PD-L1+ immune cells.ConclusionsThis work presents a unique human 3D model for the study of immune effects of anti-HER2 biologicals, which can be used to test novel therapy regimens and improve anti-tumor immune function.

Project description:BackgroundIdentification of HER2-positive breast cancers with high anti-HER2 sensitivity could help de-escalate chemotherapy. Here, we tested a clinically applicable RNA-based assay that combines ERBB2 and the HER2-enriched (HER2-E) intrinsic subtype in HER2-positive disease treated with dual HER2-blockade without chemotherapy.MethodsA research-based PAM50 assay was applied in 422 HER2-positive tumors from five II-III clinical trials (SOLTI-PAMELA, TBCRC023, TBCRC006, PER-ELISA, EGF104090). In SOLTI-PAMELA, TBCRC023, TBCRC006, and PER-ELISA, all patients had early disease and were treated with neoadjuvant lapatinib or pertuzumab plus trastuzumab for 12-24 weeks. Primary outcome was pathological complete response (pCR). In EGF104900, 296 women with advanced disease were randomized to receive either lapatinib alone or lapatinib plus trastuzumab. Progression-free survival (PFS), overall response rate (ORR), and overall survival (OS) were evaluated.ResultsA total of 305 patients with early and 117 patients with advanced HER2-positive disease were analyzed. In early disease, HER2-E represented 83.8% and 44.7% of ERBB2-high and ERBB2-low tumors, respectively. Following lapatinib and trastuzumab, the HER2-E and ERBB2 (HER2-E/ERBB2)-high group showed a higher pCR rate compared to the rest (44.5%, 95% confidence interval [CI] = 35.4% to 53.9% vs 11.6%, 95% CI = 6.9% to 18.0%; adjusted odds ratio [OR] = 6.05, 95% CI = 3.10 to 11.80, P < .001). Similar findings were observed with neoadjuvant trastuzumab and pertuzumab (pCR rate of 66.7% in HER2-E/ERBB2-high, 95% CI = 22.3% to 95.7% vs 14.7% in others, 95% CI = 4.9% to 31.1%; adjusted OR = 11.60, 95% CI = 1.66 to 81.10, P = .01). In the advanced setting, the HER2-E/ERBB2-high group was independently associated with longer PFS (hazard ratio [HR] = 0.52, 95% CI = 0.35 to 0.79, P < .001); higher ORR (16.3%, 95% CI = 8.9% to 26.2% vs 3.7%, 95% CI = 0.8% to 10.3%, P = .02); and longer OS (HR = 0.66, 95% CI = 0.44 to 0.97, P = .01).ConclusionsCombining HER2-E subtype and ERBB2 mRNA into a single assay identifies tumors with high responsiveness to HER2-targeted therapy. This biomarker could help de-escalate chemotherapy in approximately 40% of patients with HER2-positive breast cancer.

Project description:ObjectiveAberrant expression of HER2/neu and PIK3CA gene products secondary to amplification/mutations are common in high-grade-serous-endometrial (USC) and ovarian-cancers (HGSOC). Because scant information is currently available in the literature on the potential negative effect of PIK3CA mutations on the activity of afatinib, in this study we evaluate for the first time the role of oncogenic PIK3CA mutations as a potential mechanism of resistance to afatinib in HGSOC and USC overexpressing HER2/neu.MethodsWe used six whole-exome-sequenced primary HGSOC/USC cell-lines and three xenografts overexpressing HER2/neu and harboring mutated or wild-type PIK3CA/PIK3R1 genes to evaluate the role of PI3K-mutations as potential mechanism of resistance to afatinib, an FDA-approved pan-c-erb-inhibitor in clinical trials in USC. Primary-USC harboring wild-type-PIK3CA gene was transfected with plasmids encoding oncogenic PIK3CA-mutations (H1047R/E545K). The effect of afatinib on HER2/PI3K/AKT/mTOR pathway was evaluated by immunoblotting.ResultsWe found PI3K wild-type cell-lines to be significantly more sensitive (lower IC50) than PI3K-mutated cell-lines p = 0.004). In vivo, xenografts of primary cell-line USC-ARK2, transfected with the PIK3CA-H1047R or E545K hotspot-mutations, exhibited significantly more rapid tumor growth when treated with afatinib, compared to mice harboring ARK2-tumors transfected with wild-type-PIK3CA (p = 0.041 and 0.001, respectively). By western-blot, afatinib effectively reduced total and phospho-HER2 proteins in all cell-lines. However, H1047R/E545K-PIK3CA-transfected-ARK2-cells demonstrated a greater compensatory increase in phosphorylated-AKT proteins after afatinib exposure when compared to controls ARK2.ConclusionsOncogenic PI3K mutations may represent a major mechanism of resistance to afatinib. Combinations of c-erb with PIK3CA, AKT or mTOR inhibitors may be necessary to more efficiently block the PIK3CA/AKT/mTOR pathway.

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HER2-Overexpressing Breast Cancers Amplify FGFR Signaling upon Acquisition of Resistance to Dual Therapeutic Blockade of HER2.

Publications

HER2-Overexpressing Breast Cancers Amplify FGFR Signaling upon Acquisition of Resistance to Dual Therapeutic Blockade of HER2.

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