HER2 Fusions Research Articles

Clinical characteristics and treatment outcomes of HER2 mutation and HER2 fusion in 22 patients with advanced breast cancer.

The clinical characteristics and efficacy of human epidermal growth factor receptor-2 (HER-2)-directed agents against HER2 mutations and HER2 fusions in breast cancer are obscure due to their low frequency. We conducted a retrospective study in patients with advanced breast cancer harboring HER2 mutations and/or HER2 fusions between January 1, 2017 and January 1, 2021. Among a total of 22 patients, 17 HER2 mutations were detected, including L755S, S310F, R100=, V777L, R897W, T862A, 440-17C > G, H878Y, V842I, 73 + 9G > C, T278fs, E1069K, L755P, 226-11C > T, 574 + 12C>T, L114V and P128L. The majority of patients had ductal carcinoma, which mostly coexisted with HER2 amplification/overexpression. The median progression-free survival (PFS) of the 22 patients was 6.9 months (95% CI: 4.7, 9.1) in the first-line setting. The median PFS of patients who received first-line trastuzumab-based regimens was significantly longer than that of patients who received a first-line tyrosine kinase inhibitor (TKI) (10.8 months [95% CI: 2.9, 18.7] vs. 1.9 months [95% CI: 0.8, 3.0], p < 0.005). A total of 14 patients were treated with anti-HER2 antibody-drug conjugate (ADC), among whom the median treatment line of first-time of administration of anti-HER2 ADC was 4.5 (range, 1-10). Anti-HER2 ADC reached an objective response rate (ORR) of 42.9%, a disease control rate (DCR) of 85.7% and a median PFS of 7.3 months (95% CI: 4.4-10.1) from the first-time of administration. Our data demonstrated the clinical benefit of anti-HER2 treatment in Chinese breast cancer patients harboring HER2 mutation and/or HER2 fusion. The value of immunotherapy and treatment selection among individual HER2 variants needs further study.

Clinical Implication of HER2 Aberration in Patients With Metastatic Cancer Using Next-Generation Sequencing: A Pan-Tumor Analysis.

Human epidermal growth factor receptor 2 (HER2) protein expression or gene amplification is a significant predictive biomarker for identifying patients with cancer, who may benefit from HER2-targeted therapy. The aim of this study was to survey the proportion of patients who had HER2 aberration and to investigate the correlation between HER2 amplification and HER2 overexpression in immunohistochemistry (IHC) as a real-world data. We surveyed the incidence of HER2 aberration including mutation (single-nucleotide variant [SNV]), amplification (copy-number variation), and fusion by next-generation sequencing (NGS) in 2,119 patients with cancer from Samsung Medical Center in South Korea. Of 2,119 patients with cancer, 189 patients (8.9%) had HER2 aberration in their tumor specimen. Of 189 patients, 113 (5.3%) patients had HER2 amplification, 82 (3.9%) patients had HER2 mutations, and 11 (0.5%) patients had HER2 fusion. Of note, 10 patients (0.5%) had concurrent HER2 amplification and HER2 fusion. In addition, we identified that HER2 protein overexpression was strongly related to HER2 amplification by NGS. Of 74 patients with HER2 amplification only by NGS test, 64 patients (86.5%) had HER2 overexpression by IHC. Of 10 patients with concurrent HER2 amplification and fusion, 80% patients were HER2 overexpression. Among 51 patients with only HER2 mutation (SNV), 9 patients (17.6%) were HER2 (+). Interestingly, almost all patients with colorectal cancer (11 of 12) with HER2 amplification had very strong HER2 overexpression (3+) in their tumor specimen. In conclusion, we showed that when patients with metastatic cancer receive NGS test, approximately 8.9% have HER2 aberrations in their tumor specimen. Most patients have HER2 amplification, and a small percentage of patients have HER2 fusion. A great majority of patients with HER2 amplification and/or HER2 fusion had HER2 (+) tumor by IHC.

P2.14-49 Molecular Characteristics of HER2 Mutations in Non-Small Cell Lung Cancer

Earlier clinical trials targeting on HER2 exon 20 mutations show promising results. However, target therapy also had shown a favorable effect on non-tyrosine kinase domain (non-TKD) mutations in preliminary studies and case report, while no systemic study was reported about non-TKD mutations in HER2. Hence, the study aims to comprehensively outline the mutation landscape of HER2 in NSCLC. HER2 profile data (patients, N=5,222) from thirteen NSCLC studies in the cBioPortal for Cancer Genomics was screened. Finally, after excluding duplicated data (n=2,725) and no HER2 profile data (n=563), 1,934 individuals were enrolled in the analysis. The mutation subtype, mutation type, mutation region, biological effect of mutations referred to OncoKB, and HER2 copy number variation were described. 4.3% (84/1934) of NSCLC patients were detected with HER2 mutation, and three patients carried double HER2 mutations, totally eighty-seven HER2 mutations were identified in the study. Fifty-three HER2 mutation subtypes were identified, and the most common mutation subtypes were Y772_A775dup (24%, 21/87), S310F (6%, 5/87), G776delinsVC (5%, 4/87) and G778_P780dup (5%, 4/87) respectively. HER2 fusion was identified in 8% (7/87) of mutations with a tendency to concurrent with HER2 copy number increased (5 amplification, 2 copy number gain). As for mutation region, 43% (37/87) of mutations occurred in TKD, while biological effect was not validated in 16% (6/37) of TKD mutations. Notably, biological effect of 56% mutations was inclusive or unknown. In gain of function subset, 82% (31/38) of mutations located at TKD, 13% (5/38) and 5% (2/38) were located at furin-like cysteine rich region and transmembrane domain. Mutation subtypes were diverse in HER2. Though accounting for more than half of HER2 mutations, the effect of non-TKD mutations was fewly understood rather than TKD mutations. Biological effect and clinical implication of non-TKD mutations need to be further investigated in the near future.

Oncogenic HER2 fusions in gastric cancer.

BackgroundGenetic amplification of HER2 drives tumorigenesis and cancer progression in a subset of patients with gastric cancer (GC), and treatment with trastuzumab, a humanized HER2-neutralizing antibody, improves the overall survival rate of HER2-positive patients. However, a considerable portion of the patients does not respond to trastuzumab and the molecular mechanisms underlying the intrinsic resistance to anti-HER2 therapy in GC is not fully understood.MethodsWe performed whole-transcriptome sequencing on 21 HER2-positive tumor specimens from Chinese GC patients. Whole genome sequencing was performed on the three samples with HER2 fusion to discover the DNA integration structure. A multicolor FISH assay for HER2 split screening was conducted to confirm HER2 fusion and IHC (HercepTest™) was used to detect the membranous expression of HER2. Fusion cDNA were transfected into NIH/3T3 cells and generate stable cell line by lentivirus. The expression of exogenous HER2 fusion proteins and pHER2 were examined by western blot analysis. In vitro efficacy studies were also conducted by PD assay and softagar assay in cell line expression wild type and fusion HER2. T-DM1 was used to assess its binding to NIH/3T3 cells ectopically expressing wild-type and fusion HER2. Finally, the anti-tumor efficacy of trastuzumab was tested in NIH/3 T3 xenografts expressing the HER2 fusion variants.ResultsWe identified three new HER2 fusions with ZNF207, MDK, or NOS2 in 21 HER2-amplified GC samples (14%; 3/21). Two of the fusions, ZNF207-HER2, and MDK-HER2, which are oncogenic, lead to aberrant activation of HER2 kinase. Treatment with trastuzumab inhibited tumor growth significantly in xenografts expressing MDK-HER2 fusion. In contrast, trastuzumab had no effect on the growth of xenografts expressing ZNF207-HER2 fusion, due to its inability to bind to trastuzumab.ConclusionsOur results provide the molecular basis of a novel resistance mechanism to trastuzumab-based anti-HER2 therapy, supporting additional molecule stratification within HER2-positive GC patients for more effective therapy options.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0476-2) contains supplementary material, which is available to authorized users.

Chimeric Rat/Human HER2 Efficiently Circumvents HER2 Tolerance in Cancer Patients

Despite the great success of HER2 vaccine strategies in animal models, effective clinical results have not yet been obtained. We studied the feasibility of using DNA coding for chimeric rat/human HER2 as a tool to break the unresponsiveness of T cells from patients with HER2-overexpressing tumors (HER2-CP). Dendritic cells (DCs) generated from patients with HER2-overexpressing breast (n = 28) and pancreatic (n = 16) cancer were transfected with DNA plasmids that express human HER2 or heterologous rat sequences in separate plasmids or as chimeric constructs encoding rat/human HER2 fusion proteins and used to activate autologous T cells. Activation was evaluated by IFN-γ ELISPOT assay, perforin expression, and ability to halt HER2+ tumor growth in vivo. Specific sustained proliferation and IFN-γ production by CD4 and CD8 T cells from HER2-CP was observed after stimulation with autologous DCs transfected with chimeric rat/human HER2 plasmids. Instead, T cells from healthy donors (n = 22) could be easily stimulated with autologous DCs transfected with any human, rat, or chimeric rat/human HER2 plasmid. Chimeric HER2-transfected DCs from HER2-CP were also able to induce a sustained T-cell response that significantly hindered the in vivo growth of HER2(+) tumors. The efficacy of chimeric plasmids in overcoming tumor-induced T-cell dysfunction relies on their ability to circumvent suppressor effects exerted by regulatory T cells (Treg) and/or interleukin (IL)-10 and TGF-β1. These results provide the proof of concept that chimeric rat/human HER2 plasmids can be used as effective vaccines for any HER2-CP with the advantage of being not limited to specific MHC. Clin Cancer Res; 20(11); 2910-21. ©2014 AACR.

Immunization with a HSP65–HER2 fusion peptide selectively eliminates HER2+ B16 melanoma cells in a xenograft tumor mouse model

HER2/neu peptide-based vaccines can eliminate human tumors overexpressing the human epidermal growth factor receptor 2 (HER2/neu), but the efficacy of this therapeutic strategy is suboptimal. Heat shock proteins (HSPs) are capable of eliciting efficient cytotoxic T lymphocyte (CTL) responses by cross-presentation. To evaluate whether immunization with a HSP65-HER2 fusion peptide could selectively eliminate HER2(+) B16 melanoma cells in a xenograft tumor mouse model, a HSP65-HER2 fusion peptide was incubated with immature dendritic cells (iDCs) in vitro to determine whether loading of iDCs with HSP65-HER2 could induce the expression of the immunomodulatory cell surface molecule, CD86. In vivo mouse immunizations with HSP65-HER2 or PBS (control) were performed to determine the antitumor effects by longitudinally monitoring changes in tumor volume, weight, and incidence. The effects on percentages of HER2(+) B16 cells in tumors were assessed by confocal microscopy and flow cytometry. The results indicated that loading of iDCs with HSP65-HER2 induced the expression of CD86 in vitro, suggesting that the hybrid antigen was able to stimulate an immune response. Immunization with HSP65-HER2 had no significant influence on tumor weight or volume but significantly reduced tumor incidence (62.5% in mice injected with 25μg of HSP65-HER2 vs. 100% in PBS-injected controls; P < 0.05). Confocal microscopy and flow cytometry analyses revealed that HSP65-HER2 immunization significantly reduced the percentages of HER2(+) B16 cells in xenografted tumors (1.86% vs. 30.56% in PBS-injected controls; P = 0.01). Our findings suggest that immunization with the HSP65-HER2 fusion peptide selectively eliminates HER2(+) B16 melanoma cells in a xenograft tumor mouse model and may represent a novel and efficacious targeted therapy of HER2/neu(+) tumors.

A Single Vaccination with Polyomavirus VP1/VP2Her2 Virus-Like Particles Prevents Outgrowth of HER-2/neu–Expressing Tumors

Murine polyomavirus (MPyV) VP1 virus-like particles (VLPs), containing a fusion protein between MPyV VP2 and the extracellular and transmembrane domain of HER-2/neu (Her2), Her2(1-683)PyVLPs, were tested for their ability to vaccinate against Her2-expressing tumors in two different in vivo models. Protection was assessed both against a lethal challenge with a BALB/c mammary carcinoma transfected with human Her2 (D2F2/E2) and against the outgrowth of autochthonous mammary carcinomas in BALB-neuT mice, transgenic for the activated rat Her2 oncogene. A single injection of Her2(1-683)PyVLPs before tumor inoculation induced a complete rejection of D2F2/E2 tumor cells in BALB/c mice. Similarly, a single injection of Her2(1-683)PyVLPs at 6 weeks of age protected BALB-neuT mice with atypical hyperplasia from a later outgrowth of mammary carcinomas, whereas all controls developed palpable tumors in all mammary glands. VLPs containing only VP1 and VP2 did not induce protection. The protection elicited by Her2(1-683)PyVLPs vaccination was most likely due to a cellular immune response because a Her2-specific response was shown in an ELISPOT assay, whereas antibodies against Her2 were not detected in any of the two models. The results show the feasibility of using MPyV-VLPs carrying Her2 fusion proteins as safe and efficient vaccines against Her2-expressing tumors.