Prevalence and role of HER2 mutations in cancer

Antibody-Drug Conjugates for the Treatment of Breast Cancer

Metastatic breast cancer (BC) is currently an incurable disease. Besides endocrine therapy and targeted agents, chemotherapy is often used in the treatment of this disease. However, lack of tumor specificity and toxicity associated with dose exposure limit the manageability of cytotoxic agents. Antibody-drug conjugates (ADCs) are a relatively new class of anticancer drugs. By merging the selectivity of monoclonal antibodies with the cytotoxic properties of chemotherapy, they improve the therapeutic index of antineoplastic agents. Three core components characterize ADCs: the antibody, directed to a target antigen; the payload, typically a cytotoxic agent; a linker, connecting the antibody to the payload. The most studied target antigen is HER2 with some agents, such as trastuzumab deruxtecan, showing activity not only in HER2-positive, but also in HER2-low BC patients, possibly due to a bystander effect. This property to provide a cytotoxic impact also against off-target cancer cells may overcome the intratumoral heterogeneity of some target antigens. Other cancer-associated antigens represent a strategy for the development of ADCs against triple-negative BC, as shown by the recent approval of sacituzumab govitecan. In this review, we discuss the current landscape of ADC development for the treatment of BC, as well as the possible limitations of this treatment.

Antibody-drug conjugates in solid tumors: a look into novel targets

Antibody-drug conjugates (ADCs) are a relatively new class of anticancer agents designed to merge the selectivity of monoclonal antibodies with cell killing properties of chemotherapy. They are commonly described as the "Trojan Horses" of therapeutic armamentarium, because of their capability of directly conveying cytotoxic drug (payloads) into the tumor space, thus transforming chemotherapy into a targeted agent. Three novel ADCs have been recently approved, i.e., trastuzumab deruxtecan, sacituzumab govitecan and enfortumab vedotin, respectively, targeting HER2, Trop2 and Nectin4. Thanks to progressive advances in engineering technologies these drugs rely on, the spectrum of diseases sensitive to these drugs as well as their indications are in continuous expansion. Several novel ADCs are under evaluation, exploring new potential targets along with innovative payloads. This review aims at providing a summary of the technology behind these compounds and at presenting the latest ADCs approved in solid tumors, as well as at describing novel targets for ADCs under investigation and new strategies to optimize their efficacy in solid tumors.

The mutational repertoire of uterine sarcomas and carcinosarcomas in a Brazilian cohort: A preliminary study

OBJECTIVES

The present study aimed to contribute to the catalog of genetic mutations involved in the carcinogenic processes of uterine sarcomas (USs) and carcinosarcomas (UCSs), which may assist in the accurate diagnosis of, and selection of treatment regimens for, these conditions.

METHODS

We performed gene-targeted next-generation sequencing (NGS) of 409 cancer-related genes in 15 US (7 uterine leiomyosarcoma [ULMS], 7 endometrial stromal sarcoma [ESS], 1 adenosarcoma [ADS]), 5 UCS, and 3 uterine leiomyoma (ULM) samples. Quality, frequency, and functional filters were applied to select putative somatic variants.

RESULTS

Among the 23 samples evaluated in this study, 42 loss-of-function (LOF) mutations and 111 missense mutations were detected, with a total of 153 mutations. Among them, 66 mutations were observed in the Catalogue of Somatic Mutations in Cancer (COSMIC) database. TP53 (48%), ATM (22%), and PIK3CA (17%) were the most frequently mutated genes. With respect to specific tumor subtypes, ESS showed mutations in the PDE4DIP, IGTA10, and DST genes, UCS exhibited mutations in ERBB4, and ULMS showed exclusive alterations in NOTCH2 and HER2. Mutations in the KMT2A gene were observed exclusively in ULM and ULMS. In silico pathway analyses demonstrated that many genes mutated in ULMS and ESS have functions associated with the cellular response to hypoxia and cellular response to peptide hormone stimulus. In UCS and ADS, genes with most alterations have functions associated with phosphatidylinositol kinase activity and glycerophospholipid metabolic process.

CONCLUSION

This preliminary study observed pathogenic mutations in US and UCS samples. Further studies with a larger cohort and functional analyses will foster the development of a precision medicine-based approach for the treatment of US and UCS.

Molecular intrinsic versus clinical subtyping in breast cancer: A comprehensive review

Breast cancer is a heterogeneous disease manifesting diversity at the molecular, histological and clinical level. The development of breast cancer classification was centered on informing clinical decisions. The current approach to the classification of breast cancer, which categorizes this disease into clinical subtypes based on the detection of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and proliferation marker Ki67, is not ideal. This is manifested as a heterogeneity of therapeutic responses and outcomes within the clinical subtypes. The newer classification model, based on gene expression profiling (intrinsic subtyping) informs about transcriptional responses downstream from IHC single markers, revealing deeper appreciation for the disease heterogeneity and capturing tumor biology in a more comprehensive way than an expression of a single protein or gene alone. While accumulating evidences suggest that intrinsic subtypes provide clinically relevant information beyond clinical surrogates, it is imperative to establish whether the current conventional immunohistochemistry-based clinical subtyping approach could be improved by gene expression profiling and if this approach has a potential to translate into clinical practice.

Recent advances in HER2-targeted delivery for cancer therapy

Human epidermal growth factor receptor 2 (HER2), a tyrosine kinase receptor with a molecular mass of 185kDa, is overexpressed in several cancers, such as breast, gastric, ovary, prostate, and lung. HER2 is a promising target in cancer therapy because of its crucial role in cell migration, proliferation, survival, angiogenesis, and metastasis through various intracellular signaling cascades. This receptor is an ideal target for the delivery of chemotherapeutic agents because of its accessibility to the extracellular domain. In this review, we highlight different HER2-targeting strategies and various approaches for HER2-targeted delivery systems to improve outcomes for cancer therapy.

A pan-cancer analysis of HER2 index revealed transcriptional pattern for precise selection of HER2-targeted therapy

Background

The prevalence of HER2 alterations in pan-cancer indicates a broader range of application of HER2-targeted therapies; however, biomarkers for such therapies are still insufficient and limited to breast cancer and gastric cancer.

Methods

Using multi-omics data from The Cancer Genome Atlas (TCGA), the landscape of HER2 alterations was exhibited across 33 tumor types. A HER2 index was constructed using one-class logistic regression (OCLR). With the predictive value validated in GEO cohorts and pan-cancer cell lines, the index was then applied to evaluate the HER2-enriched expression pattern across TCGA pan-cancer types.

Findings

Increased HER2 somatic copy number alterations (SCNAs) could be divided into two patterns, focal- or arm-level. The expression-based HER2 index successfully distinguished the HER2-enriched subtype from the others and provided a stable and superior performance in predicting the response to HER2-targeted therapies both in breast tumor tissue and pan-cancer cell lines. With frequencies varying from 12.0% to 0.9%, tumors including head and neck squamous tumors, gastrointestinal tumors, bladder cancer, lung cancer and uterine tumors exhibited high HER2 indices together with HER2 amplification or overexpression, which may be more suitable for HER2-targeted therapies. The BLCA.3 and HNSC.Basal were the most distinguishable subtypes within bladder cancer and head and neck cancer respectively by HER2 index, implying their potential benefits from HER2-targeted therapies.

Interpretation

As a pan-cancer predictive biomarker of HER2-targeted therapies, the HER2 index could help identify potential candidates for such treatment in multiple tumor types by combining with HER2 multi-omics features. The discoveries of our study highlight the importance of incorporating transcriptional pattern into the assessment of HER2 status for better patient selection.

Funding

The National Key Research and Development Program of China; Clinical Research and Cultivation Project of Shanghai ShenKang Hospital Development Center.

Neratinib in patients with HER2-mutant, metastatic cervical cancer: Findings from the phase 2 SUMMIT basket trial

OBJECTIVE

Somatic HER2 mutations occur in ~5% of cervical cancers and are considered oncogenic and associated with poor prognosis. Neratinib, an irreversible pan-HER tyrosine kinase inhibitor, is active in multiple HER2-mutant cancers. SUMMIT is a phase II basket trial investigating the efficacy and safety of neratinib in solid tumors.

METHODS

Patients with HER2-mutant, persistent, metastatic/recurrent cervical cancer with disease progression after platinum-based treatment for advanced/recurrent disease received oral neratinib 240 mg/day with mandatory loperamide prophylaxis during cycle 1. The primary endpoint was confirmed objective response rate (ORR). Secondary endpoints included: response duration (DOR); clinical benefit rate (CBR); progression-free survival (PFS); overall survival (OS); safety.

RESULTS

Sixteen eligible patients were enrolled; 10 (62.5%) had endocervical adenocarcinoma. The most common HER2 mutation was S310F (63% of patients). Three of 12 RECIST-measurable patients had confirmed partial responses (ORR 25%; 95%CI 5.5-57.2%); 3 had stable disease ≥16 weeks (CBR 50%; 95%CI 21.1-78.9%). DOR for responders were 5.6, 5.9, and 12.3 months. Median PFS was 7.0 months (95%CI 0.7-18.3 months); median OS was 16.8 months (95%CI 4.1-NE months). Diarrhea (75%), nausea (44%), and decreased appetite (38%) were the most common adverse events. One patient (6%) reported grade 3 diarrhea. There were no grade 4 events, and no diarrhea-related treatment discontinuations.

CONCLUSIONS

Neratinib monotherapy showed evidence of activity in heavily pretreated patients with HER2-mutant cervical cancer, with no new safety signals. Given the few effective options for cervical cancer after platinum-based therapy failure, neratinib warrants further investigation in this molecularly defined patient population.

TRIAL REGISTRATION NUMBER

NCT01953926 (ClinicalTrials.gov), 2013-002872-42 (EudraCT).

HER2-Mediated Internalization of Cytotoxic Agents in ERBB2 Amplified or Mutant Lung Cancers

Amplification of and oncogenic mutations in ERBB2, the gene encoding the HER2 receptor tyrosine kinase, promote receptor hyperactivation and tumor growth. Here we demonstrate that HER2 ubiquitination and internalization, rather than its overexpression, are key mechanisms underlying endocytosis and consequent efficacy of the anti-HER2 antibody-drug conjugates (ADC) ado-trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd) in lung cancer cell lines and patient-derived xenograft models. These data translated into a 51% response rate in a clinical trial of T-DM1 in 49 patients with ERBB2-amplified or -mutant lung cancers. We show that cotreatment with irreversible pan-HER inhibitors enhances receptor ubiquitination and consequent ADC internalization and efficacy. We also demonstrate that ADC switching to T-DXd, which harbors a different cytotoxic payload, achieves durable responses in a patient with lung cancer and corresponding xenograft model developing resistance to T-DM1. Our findings may help guide future clinical trials and expand the field of ADC as cancer therapy. SIGNIFICANCE: T-DM1 is clinically effective in lung cancers with amplification of or mutations in ERBB2. This activity is enhanced by cotreatment with irreversible pan-HER inhibitors, or ADC switching to T-DXd. These results may help address unmet needs of patients with HER2-activated tumors and no approved targeted therapy.See related commentary by Rolfo and Russo, p. 643.This article is highlighted in the In This Issue feature, p. 627.

Somatic Mutations in HER2 and Implications for Current Treatment Paradigms in HER2-Positive Breast Cancer

In one of every four or five cases of breast cancer, the human epidermal growth factor receptor-2 (HER2) gene is overexpressed. These carcinomas are known as HER2-positive. HER2 overexpression is linked to an aggressive phenotype and a lower rate of disease-free and overall survival. Drugs such as trastuzumab, pertuzumab, lapatinib, neratinib, and the more recent afatinib target the deregulation of HER2 expression. Some authors have attributed somatic mutations in HER2, a role in resistance to anti-HER2 therapy as differential regulation of HER2 has been observed among patients. Recently, studies in metastatic ER + tumors suggest that some HER2 mutations emerge as a mechanism of acquired resistance to endocrine therapy. In an effort to identify possible biomarkers of the efficacy of anti-HER2 therapy, we here review the known single-nucleotide polymorphisms (SNPs) of the HER2 gene found in HER2-positive breast cancer patients and their relationship with clinical outcomes. Information was recompiled on 11 somatic HER2 SNPs. Seven polymorphisms are located in the tyrosine kinase domain region of the gene contrasting with the low number of mutations found in extracellular and transmembrane areas. HER2-positive patients carrying S310F, S310Y, R678Q, D769H, or I767M mutations seem good candidates for anti-HER2 therapy as they show favorable outcomes and a good response to current pharmacological treatments. Carrying the L755S or D769Y mutation could also confer benefits when receiving neratinib or afatinib. By contrast, patients with mutations L755S, V842I, K753I, or D769Y do not seem to benefit from trastuzumab. Resistance to lapatinib has been reported in patients with L755S, V842I, and K753I. These data suggest that exploring HER2 SNPs in each patient could help individualize anti-HER2 therapies. Advances in our understanding of the genetics of the HER2 gene and its relations with the efficacy of anti-HER2 treatments are needed to improve the outcomes of patients with this aggressive breast cancer.

A double safety lock tumor-specific device for suicide gene therapy in breast cancer

The complexity and continuous evolution of cancer make the design of novel strategies of treatment a constant challenge in biomedicine. Moreover, most of cancer treatments are still not tumor-specific and provoke high systemic toxicity. Herein we have developed a novel selective nanodevice to eliminate tumor cells while leaving healthy ones intact. To achieve this objective, a polyplex carrier, comprising an elastin like-recombinamer covalently conjugated to an aptamer and complexed with therapeutic DNA, was tested. This carrier forms a double-lock multifunctional device due to specific binding to a tumor cell marker and the selective expression of therapeutic DNA inside human breast-cancer cells. Due to the stability provided by ELRs, the homogeneous population of polyplexes obtained showed selective toxicity against cancer cells in in vitro and in vivo assay. Inhibition of tumor progression was detected early being very significant at the end point, with a dose-dependent reduction in tumor mass. Histological studies revealed a specific reduction in tumor parenchyma and in specific tumor cell markers. These results represent an important step toward the rational development of an efficient, safe and more specialized gene-delivery device for tumor therapy.

Whole-exome sequencing of cervical carcinomas identifies activating ERBB2 and PIK3CA mutations as targets for combination therapy

The prognosis of advanced/recurrent cervical cancer patients remains poor. We analyzed 54 fresh-frozen and 15 primary cervical cancer cell lines, along with matched-normal DNA, by whole-exome sequencing (WES), most of which harboring Human-Papillomavirus-type-16/18. We found recurrent somatic missense mutations in 22 genes (including PIK3CA, ERBB2, and GNAS) and a widespread APOBEC cytidine deaminase mutagenesis pattern (TCW motif) in both adenocarcinoma (ACC) and squamous cell carcinomas (SCCs). Somatic copy number variants (CNVs) identified 12 copy number gains and 40 losses, occurring more often than expected by chance, with the most frequent events in pathways similar to those found from analysis of single nucleotide variants (SNVs), including the ERBB2/PI3K/AKT/mTOR, apoptosis, chromatin remodeling, and cell cycle. To validate specific SNVs as targets, we took advantage of primary cervical tumor cell lines and xenografts to preclinically evaluate the activity of pan-HER (afatinib and neratinib) and PIK3CA (copanlisib) inhibitors, alone and in combination, against tumors harboring alterations in the ERBB2/PI3K/AKT/mTOR pathway (71%). Tumors harboring ERBB2 (5.8%) domain mutations were significantly more sensitive to single agents afatinib or neratinib when compared to wild-type tumors in preclinical in vitro and in vivo models (P = 0.001). In contrast, pan-HER and PIK3CA inhibitors demonstrated limited in vitro activity and were only transiently effective in controlling in vivo growth of PIK3CA-mutated cervical cancer xenografts. Importantly, combinations of copanlisib and neratinib were highly synergistic, inducing long-lasting regression of tumors harboring alterations in the ERBB2/PI3K/AKT/mTOR pathway. These findings define the genetic landscape of cervical cancer, suggesting that a large subset of cervical tumors might benefit from existing ERBB2/PIK3CA/AKT/mTOR-targeted drugs.