Combination therapies for the treatment of HER2-positive breast cancer: current and future prospects

Introduction: HER2-positive disease is an aggressive subtype of breast cancer that has been revolutionized by anti-HER2 directed therapies. Multiple drugs have been developed and are currently in clinical use, including trastuzumab, lapatinib, pertuzumab, T-DM1, and neratinib, alone or combined in ‘dual HER2-blockade’ regimens.

Areas covered: A comprehensive literature review was performed regarding the current state and the future of combination regimens containing anti-HER2 agents, focusing on their efficacy, toxicity, and cost-effectiveness.

Expert commentary: The combination of trastuzumab/pertuzumab is approved in all disease settings, while trastuzumab/neratinib is approved in the adjuvant setting and trastuzumab/lapatinib in metastatic disease. Meanwhile, as breast cancer biology and resistance mechanisms become clearer, combinations with drugs like PI3K/Akt/mTOR inhibitors, CDK4/6 inhibitors, anti-PD(L)1 antibodies, endocrine therapy, and new anti-HER2 agents (panHER and HER2 tyrosine kinase inhibitors, bispecific antibodies, anti-HER3 antibodies, and antibody-drug conjugates) are being extensively tested in clinical trials. More specific strategies for the ‘triple-positive’ (estrogen receptor-positive/HER2-positive) disease are also being explored. However, there is an urgent need for the development of predictive biomarkers for a better tailoring of anti-HER2 directed therapy. This is the only way to further improve clinical outcomes and quality of life and to decrease costs and toxicities of unnecessary treatments.     

Neratinib for the treatment of HER2-positive early stage breast cancer

Introduction: Despite the advances in the treatment of HER2-positive breast cancer, resistance to actual chemotherapeutic regimens eventually occurs. Neratinib, an orally available pan-inhibitor of the ERBB family, represents an interesting new option for early-stage HER2-positive breast cancer.

Areas covered: In this article, the development of neratinib, with a special focus on its potential value in the treatment of early-stage HER2-positive breast cancer, has been reviewed. For this purpose, a literature search was conducted, including preclinical studies, early-phase trials in advanced cancer with neratinib in monotherapy and in combination, and phase II and large phase III trials in the early setting. Management of neratinib-induced toxicity, future perspectives for the drug, and ongoing trials are also discussed in this review.

Expert commentary: Neratinib is emerging as a promising oral drug for the treatment of HER2-positive breast cancer. Although FDA and EMA approval is derived from the extended adjuvant treatment, this setting may not be the ideal scenario to obtain the beneficial effects of neratinib. Confirmatory data in the neoadjuvant setting and subgroup analysis from the ExTENET trial might bring some light into the best setting for neratinib therapy. Data from confirmatory trials in the metastatic setting are also required.     

Targeted adjuvant therapy in breast cancer

Introduction: The potential of molecular targeted therapy to improve the clinical outcomes of patients with early-stage breast cancer (BC) as adjuvant therapy has been first demonstrated through endocrine treatment. The introduction of HER2 blockade, through the successful clinical development of trastuzumab, changed the natural history of HER2-positive BC subtype.

Areas covered: There are ongoing efforts to augment further the use of targeted agents as adjuvant treatment in BC, hoping that early introduction of targeted therapy blocking key oncogenic drivers of micro-residual disease, will significantly improve clinical outcomes. In the present Review, we present data through extensive search of PubMed about the following targeted adjuvant therapeutic strategies in BC: i) HER2 blockade and ongoing efforts to further augment its efficacy for patients with HER2-positive disease, ii) angiogenesis inhibition, iii) PI3K-mTOR- AKT pathway inhibition, iv) CDK4/6 inhibition, v) PARP inhibition.

Expert commentary: we provide insights about challenges and potential ways to overcome them, in terms of successful clinical development of targeted agents as adjuvant therapy for patients with BC. In particular, we emphasize the need to systematically assess minimal residual cancer burden as a way to increase the rates of successful clinical development of targeted agents in the adjuvant setting.     

Short-term outcomes of neoadjuvant hormonal therapy versus neoadjuvant chemotherapy in breast cancer: systematic review and meta-analysis of randomized controlled trials

Introduction: Estrogen receptor positive (ER⁺) breast cancer (BC) is highly hormonal therapy-responsive. The choice between neoadjuvant hormonal therapy (NHT) and neoadjuvant chemotherapy (NCT) remains controversial. The aim of this meta-analysis was to evaluate benefits and safety of NHT compared with NCT for operable BC patients.

Areas covered: Electronic databases were searched to identify randomized clinical trials (RCTs) comparing NHT and NCT for treatment of invasive and immunohistochemically ER⁺ BC. Major outcomes were clinical response rate, pathologic complete response (pCR), operation methods, recurrence, and adverse events. Five RCTs were included. The clinical response rates between NHT and NCT were not statistically different overall, or in ER-rich patients or postmenopausal women. Compared with NCT, NHT had a significant reduction of complete response rate and an increment in progressive disease rate. NHT increased rates of breast conserving surgery (BCS) and wide local excision (WLE) compared with NCT. All the other parameters were comparable. Patients receiving NHT had better tolerance than those undergoing NCT.

Expert commentary: When treating BC, NHT was well tolerated, and contributed to more BCS and WLE cases, especially in ER-rich postmenopausal patients. While for those who are eligible for chemotherapy, NCT might be better recommended due to higher response rates.     

Olaparib for the treatment of breast cancer

Introduction: Mutations in BRCA1 and BRCA2 genes account for around 2–3% of breast cancer events and more than 10% of triple negative breast cancers. Olaparib (Lynparza®), an orally administered PARP inhibitor, demonstrated clinical benefit in a phase III trial for mutated BRCA-positive HER2 negative metastatic breast cancer.

Areas covered: This review gives an overview of available preclinical and clinical data regarding olaparib, including its chemistry, mechanism of action, pharmacokinetics and pharmacodynamics, and evidence supporting antitumor efficacy and safety profile in breast cancer patients.

Expert commentary: Olaparib improves progression-free survival in germline BRCA mutated HER2 negative metastatic breast cancer patients as compared to standard chemotherapy, with a manageable toxicity profile. Efficacy is of clinical relevance especially in the context of triple negative breast cancer. However, several aspects, such as sequencing or combination of these agents with other anticancer agents and identification of appropriate biomarkers, still need to be clearly defined.     

Implementing neoadjuvant endocrine strategies in ER-positive,HER2-negative breast cancer

Introduction: Although neoadjuvant chemotherapy has been widely adopted as it increases breast conservation rates, permits the in vivo testing of the activity of chemotherapeutics and offers the opportunity to conduct translational research based on longitudinal assessments of tumor tissue, neoadjuvant endocrine therapy has been met with skepticism owing to slow regression rates and a low chance for pathologic remission.

Areas covered: Herein, the results of clinical trials comparing different endocrine agents as neoadjuvant treatment, endocrine therapy with chemotherapy, treatment duration, novel combinations and putative biomarkers are reviewed, with the aim to better understand the current and future role of this modality in clinical practice.

Expert commentary: Available evidence clearly indicates that, in properly selected patients, short-term outcomes do not differ compared to chemotherapy. In addition, the realization that its effects at the cellular level occur shortly after its initiation and have important prognostic implications, could serve as a tool for the early identification of non-responders. Ongoing trials which integrate novel agents in addition to endocrine therapies will help guide treatment decisions and may establish neoadjuvant endocrine therapy as a standard of care for well-defined patient subgroups.     

Genetic testing in women with breast cancer: implications for treatment

Introduction: Mutations in either the BRCA1 or BRCA2 genes are responsible for approximately 42,000 cases of breast cancer annually. Identifying these germline mutations in a woman with breast cancer is important because it can influence her immediate and long-term management and has important implications for other family members.

Areas covered: This review highlights how treatment-focussed genetic testing for BRCA1 and BRCA2 mutations can potentially influence cancer treatment and secondary prevention decisions in women with breast cancer.

Expert commentary: Testing women with breast cancer for BRCA1 and BRCA2 germline mutations has the potential to decrease cancer burden and improve cancer outcomes. It can help optimise surgical and systemic therapy approaches. Clinicians should actively consider whether genetic testing is appropriate for each woman with breast cancer, and if so should instigate it early in the treatment trajectory when it can most influence cancer care.     

Current and future therapies for targeting HER2 mutations in gastrointestinal cancer

Introduction: Gastrointestinal (GI) cancers altogether represent the most common cancer type. HER2 is found to be present in nearly all histologic types of GI cancers in variable degrees of expression. Over the last decade, substantial advances have been made in targeting HER2-positive cancers.

Areas covered: The present review summarizes the current progress and future directions for HER2 targeted therapies in GI cancers, including esophagogastric, pancreaticobiliary, and colon cancers. To date trastuzumab is the only anti-HER2 therapy approved for metastatic esophagogastric adenocarcinoma. Efforts are ongoing to expand the therapeutic role of HER2 to other GI cancers and overcome mechanisms of drug resistance. Novel agents and combinations are being tested in most HER2 positive GI cancers including early stage disease. These are of recent interest in colorectal cancer with studies indicating that HER2 overexpression might increase resistance to anti-EGFR therapy and may be potentially targeted.

Expert commentary: With the current ability to sequence tumors and detect genetic alterations, emphasis should be put on genomically-selected pan-tumor targeted therapies. HER2 is a perfect example of a promising drug target in GI cancers.     

Emerging data on improving response to hormone therapy: the role of novel targeted agents

Introduction: Hormone receptor positive (HR+) breast cancer represents the most common subtype of breast cancer. Metastatic HR+ breast cancer may develop resistance to standard hormone therapies, arising from genomic alterations in the estrogen receptor and/or upregulation of other signal transduction pathways.

Areas covered: In this review, we discuss hormone resistance and strategies to overcome it, from the pre-clinical and clinical perspectives. This review includes a discussion of inhibition of the PI3K/AKT/mTOR, CDK 4/6, histone deacetylation, fibroblast growth factor receptor, and immune pathways, based on review of relevant literature.

Expert commentary: Several emerging novel therapies to improve the response to hormone therapy are approved or are in development. The most promising agents at present are inhibitors of CDK 4/6 and mTOR, which have already been incorporated into treatment in the advanced stage setting and are under study for early stage disease.     

MiR-144 suppresses proliferation,invasion, and migration of breast cancer cells through inhibiting CEP55

Objective: The study aimed to investigate the molecular mechanism of miR-144 and CEP55 as well as the influence of their interaction on the cell proliferation, migration, invasion, cell cycle and cell apoptosis in breast cancer.

Methods: In this study, The Cancer Genome Atlas (TCGA, https://tcga-data.nci.nih.gov/) database was used for microarray analysis. The expressions of miR-144 and CEP55 in 40 adjacent tissues and 36 tumor tissues were examined by western blot, qRT-PCR and immunohistochemistry. The target relationship between miR-144 and CEP55 was predicted and confirmed by TargetScan and luciferase reporter assay. The cell proliferation, cell cycle and cell apoptosis in different groups were detected by MTT and flow cytometry assays, while wound healing and transwell assays were used for the cell migration and invasion tests. The regulatory effects of miR-144 and CEP55 on breast tumor were verified through nude mouse model in vivo experiment.

Results: MiR-144 was down-regulated in breast cancerous tissues and cells, whereas CEP55 expression was up-regulated in breast cancerous tissues. Moreover, there existed a target relationship between miR-144 and CEP55 and negative correlation on their expressions. MiR-144 could down-regulate CEP55 expression, thereby inhibiting proliferation, invasion, migration, retarding cell cycle and accelerating cell apoptosis. MiR-144 could inhibit cell progression through down-regulating CEP55 in vivo.

Conclusion: MiR-144 suppressed cell proliferation, migration, invasion and induced cell cycle arrest and cell apoptosis by repressing CEP55. This might provide a promising therapy for clinical treatment.     

Adjuvant trastuzumab: a 10-year overview of its benefit

Introduction: Anti-HER2 targeted therapy is one of the key advances in the treatment of breast cancer that have occurred in the last 20 years. In the adjuvant setting, the use of trastuzumab has led to prolonged and sustained survival benefit with very little toxicity as also confirmed by the 10-year follow-up results from the pivotal trials. Despite the survival improvement, several key issues are not entirely resolved in this field. These issues have led to multiple research efforts in de-escalating or escalating the standard treatment with chemotherapy and 1 year of adjuvant trastuzumab.

Areas covered: In this paper, we present an in depth overview on the state of the art on these key issues of refining decision-making in adjuvant anti-HER2 therapy.

Expert commentary: Despite many important research efforts in the field, chemotherapy plus trastuzumab for a total duration of 1 year remains the standard of care. However, recent data showed that besides standard anthracycline- and taxane-based cytotoxic therapy, alternative chemotherapy regimens can now be proposed to patients with small tumors without nodal involvement and to women at high-risk of developing cardiotoxicity. Of note, besides HER2 itself, biomarkers predicting patients who may truly benefit from anti-HER2 agents are still lacking.     

How to use neoadjuvant medical treatment to maximize surgery in melanoma

Introduction: The aim of this work is to discuss the role of neoadjuvant therapy in melanoma patients, namely the potential to improve control and surgical resectability of locoregional disease. Moreover, potential survival benefits for high-risk stage III and IV melanoma patients will be addressed.

Areas covered: In this review, the different available neoadjuvant treatments including chemotherapy, bio-chemotherapy, targeted therapy, immunotherapy and local therapy will be presented and discussed. The PubMed published articles were identified and searched using the following terms located in the publication title: neoadjuvant therapy and melanoma. Studies investigating targeted therapy, immunotherapy and local melanoma treatments were included. Clinicaltrial.gov was also used as a source for recruiting or ongoing but not recruiting neoadjuvant clinical trials, for which no published results are available.

Expert commentary: Targeted therapy and immunotherapy in a neoadjuvant setting are still under investigation and not yet approved, however several neoadjuvant trials are ongoing. Shortly, results from these trials will answer the question whether neoadjuvant treatment translates into survival benefit and improves local disease control in stage III and IV melanoma patients. Immunotherapy and targeted therapy will play as relevant a role as in the metastatic setting, whereas chemotherapy will be used seldom.     

Fulvestrant for the treatment of advanced breast cancer

Introduction: The current issues with endocrine therapy for treatment of advanced breast cancer include balance of efficacy of therapy versus tolerability as well as hormone resistance. The efficacy of fulvestrant, a selective oestrogen receptor degrader (SERD), has been demonstrated in hormone receptor positive patients previously untreated or treated with hormonal therapy.

Areas covered: This article discusses the journey of fulvestrant licensing, its efficacy in combination with other endocrine therapies and the future role it may have within breast cancer treatment.

Expert commentary: Within phase III trials, fulvestrant has demonstrated equivalent or improved clinical efficacy when compared with established endocrine agents. In the recent decade, fulvestrant has achieved licensing as a second line agent in non-operative advanced breast cancer at initially 250mg, increasing to 500mg. Presently, fulvestrant is licensed globally as first line endocrine management for advanced breast cancer in post-menopausal women. Early combination trials of fulvestrant and cyclin dependent kinase 4/6 inhibitors have demonstrated good clinical efficacy with improved progression free survival when compared to fulvestrant alone.     

Evaluating the addition of oxaliplatin to single agent fluoropyrimidine in the treatment of locally advanced rectal cancer: a systematic review and meta-analysis

Introduction: Multimodality treatment of patients with locally advanced rectal cancer (LARC) has significantly improved local disease control, however the unaltered overall survival (OS) implicates an inability to further control micrometastases, providing rationale for intensified systemic treatment.

A systematic review was conducted to evaluate the efficacy and toxicity of adding oxaliplatin to a fluoropyrimidine (intervention) compared with fluoropyrimidine alone (control) in the treatment of LARC.

Methods: We searched CENTRAL, Medline Ovid, PubMed and EMBASE databases. Randomised trials comparing the intervention and control delivered either pre- or post-operatively were included.

Results: Seven trials involving 4444 patients were identified; five studies evaluated the intervention vs control preoperatively; one study peri-operatively; and one, post-operatively. There was no significant difference in OS with oxaliplatin addition, HR 0.89, 95% CI, 0.75 to 1.06. There was however an improvement in disease free survival, 3-year local and distant recurrence rates (RR) favouring oxaliplatin. Preoperative oxaliplatin improved pathological complete response (pCR), but with a greater toxicity and reduced compliance with radiation.

Conclusion: There is no OS benefit with oxaliplatin, despite improved pCR, local and distant RR. Before drawing definitive conclusions, longer follow-up in included trials and availability of published data from other eligible studies, including the induction setting, are needed.     

Hypofractionated radiation treatment in the management of breast cancer

Introduction: The standard treatment for early-stage breast cancer is breast conservation therapy, consisting of breast conserving surgery followed by adjuvant radiation treatment (RT). Conventionally-fractionated whole breast irradiation (CF-WBI) has been the standard RT regimen, but recently shorter courses of hypofractionated whole breast irradiation (HF-WBI) have been advocated for patient convenience and reduction in healthcare costs and resources.

Areas covered: This review covers the major randomized European and Canadian trials comparing HF-WBI to CF-WBI with long-term follow-up, as well as additional recently closed randomized trials that further seek to define the applicability of HF-WBI in clinical practice. Randomized data is summarized in terms of clinical utility and for a variety of clinical applications. Recently published consensus guidelines and practical implementation of HF-WBI including its broader effect on the healthcare system are reviewed. Finally, an assessment of the emerging evidence in support of hypofractionation for locally advanced disease is presented.

Expert commentary: HF-WBI has replaced CF-WBI as the accepted standard of care in most women with early-stage breast cancer who do not require regional nodal irradiation. Early data supports the continued study of hypofractionation in the locally advanced setting, however broad adoption awaits longer follow-up and additional data from ongoing clinical trials.     

Atypical epithelial hyperplasia of the breast: state of the art

Introduction: Atypical epithelial hyperplasia (AEH) of the breast is considered benign histological lesions with breast cancer risk. This review focuses on clinical signification and management of AEH that remains controversial.

Areas covered: A review of published studies was performed using medline database. In this review, we fully describe the current evidence available. In particular, we describe 1) data from immunohistochemistry and molecular studies that suggest AEH is a precursor of breast cancer; 2) epidemiological studies demonstrate low rate of breast cancer in women with AEH; 3) surgical excision is necessary after diagnosis of AEH, such as lobular carcinoma in situ or atypical ductal hyperplasia, on core needle biopsy; 4) although current recommendations are evolving to fewer (if not no) excisions for flat epithelial with atypia and classic lobular neoplasia found on percutaneous biopsy (without radiologic indications for excision).

Expert commentary: HEA management steel need prospective evidences, but recent retrospective data give some clue for less invasive management for some of HEA.     

Nivolumab in squamous cell carcinoma of the head and neck

Introduction: The prognosis of recurrent/metastatic (R/M) squamous cell carcinoma of the head and neck (HNSCC) after failure of first line chemotherapy is dismal. Until the publication of the results of CheckMate 141, not a single agent provided any survival benefit as a second line treatment for R/M HNSCC.

Areas covered: A comprehensive review of the literature was conducted on the role of nivolumab in HNSCC.

Expert commentary: Nivolumab is approved by the Food and Drug Administration for the treatment of patients based on the results of CheckMate 141 showing an overall survival benefit as compared to standard care (single agent docetaxel, methotrexate, or cetuximab). Of particular interest are immune-related adverse events which should be managed according to published guidelines.     

Managing side effects in adjuvant endocrine therapy for breast cancer

Introduction: Recent improvements in the survival of hormone-responsive breast cancer are strongly associated with therapeutic advances, particularly with the uptake of adjuvant endocrine therapy. Nevertheless, endocrine therapy is also linked with adverse effects that impact quality of life, social function, and adherence to treatment.

Areas covered: This review examines the spectrum and consequences of adverse effects of tamoxifen and aromatase inhibitors, and the pharmacological and non-pharmacological approaches to mitigate some of the most frequent and disturbing side effects of endocrine therapy (including vasomotor, musculoskeletal, and vulvovaginal symptoms). The authors performed a qualitative analysis of English papers indexed in PubMed through May 2017, including meta-analysis, randomized controlled trials, observational studies, and systematic reviews.

Expert commentary: Side effects of endocrine treatments are frequent and often underestimated in the care of breast cancer survivors, leading to a poor adherence to treatments that can compromise oncological outcomes. Many of the most common adverse events can be mitigated through pharmacological and non-pharmacological approaches that should be discussed and offered to patients in a dedicated setting of care.