Emerging treatments for HER2-positive early-stage breast cancer: focus on neratinib

Compounds targeting ferroptosis in breast cancer: progress and their therapeutic potential

In recent years, there has been a significant increase in the incidence of Breast cancer (BC), making it the most common cancer among women and a major threat to women's health. Consequently, there is an urgent need to discover new and effective strategies for treating BC. Ferroptosis, a novel form of cell death characterized by the accumulation of iron-dependent lipid reactive oxygen species, has emerged as a distinct regulatory pathway separate from necrosis, apoptosis, and autophagy. It is widely recognized as a crucial factor in the development and progression of cancer, offering a promising avenue for BC treatment. While significant progress has been made in understanding the mechanisms of ferroptosis in BC, drug development is still in its early stages. Numerous compounds, including phytochemicals derived from dietary sources and medicinal plants, as well as synthetic drugs (both clinically approved medications and laboratory reagents), have shown the ability to induce ferroptosis in BC cells, effectively inhibiting tumor growth. This comprehensive review aims to examine in detail the compounds that target ferroptosis in BC and elucidate their potential mechanisms of action. Additionally, the challenges associated with the clinical application of ferroptosis-inducing drugs are discussed, offering valuable insights for the development of novel treatment strategies for BC.

Neratinib for HER2-positive breast cancer with an overlooked option

Positive human epidermal growth factor receptor 2 (HER2) expression is associated with an increased risk of metastases especially those to the brain in patients with advanced breast cancer (BC). Neratinib as a tyrosine kinase inhibitor can prevent the transduction of HER1, HER2 and HER4 signaling pathways thus playing an anticancer effect. Moreover, neratinib has a certain efficacy to reverse drug resistance in patients with BC with previous HER2 monoclonal antibody or targeted drug resistance. Neratinib, as monotherapy and in combination with other therapies, has been tested in the neoadjuvant, adjuvant, and metastatic settings. Neratinib with high anticancer activity is indicated for the prolonged adjuvant treatment of HER2-positive early BC, or in combination with other drugs including trastuzumab, capecitabine, and paclitaxel for the treatment of advanced HER2-positive BC especially cancers with central nervous system (CNS) metastasis to reduce the risk of BC recurrence. This article reviewed the pharmacological profiles, efficacy, safety, tolerability, and current clinical trials pertaining to neratinib, with a particular focus on the use of neratinib in patients with metastatic breast cancer (MBC) involving the CNS. We further discussed the use of neratinib for HER2-negative and HER2-mutant breast cancers, and mechanisms of resistance to neratinib. The current evidence suggests that neratinib has promising efficacy in patients with BC which is at least non-inferior compared to previous therapeutic regimens. The most common AE was diarrhea, and the incidence, severity and duration of neratinib-related grade 3 diarrhea can be reduced with loperamide. Of note, neratinib has the potential to effectively control and prevent brain metastasis in patients with advanced BC, providing a therapeutic strategy for HER2-positive BC.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

How to Optimise Extended Adjuvant Treatment with Neratinib for Patients with Early HER2+ Breast Cancer

Over the last 20 years, treatment of patients with human epidermal growth factor receptor 2-positive (HER2+) early breast cancer has considerably improved. The development and addition of (neo)adjuvant trastuzumab to chemotherapy in patients with early HER2+ breast cancer (EHBC) has been shown to provide improvements in both disease-free survival (DFS) and overall survival, with some patients having a good prognosis being candidates for chemotherapy de-escalation strategies. However, despite such promising clinical outcomes, a significant proportion of patients still recur calling for the development of new preventive approaches. To this aim, the use of (neo)adjuvant trastuzumab for longer than one year or followed by lapatinib were tested without additional clinical improvement. Based on more recent advances, therapeutic strategies for patients with HER2+ tumours are now incorporating the use of newer (neo)adjuvant treatments, such as pertuzumab and trastuzumab emtansine, which have shown to further improve the invasive DFS (iDFS) benefit gained with trastuzumab. In this context, the tyrosine kinase inhibitor neratinib is approved in Europe for the extended adjuvant treatment of adult patients with early-stage hormone receptor-positive HER2+ breast cancer who completed adjuvant trastuzumab-based therapy less than one year ago. Clinical data have demonstrated that neratinib significantly improves iDFS when used for the total recommended duration of 12 months. This review paper provides an overview of the treatment of patients with EHBC, with a focus on the post-trastuzumab use of neratinib.

Pathophysiology of neratinib-induced diarrhea in male and female rats: microbial alterations a potential determinant

BACKGROUND

Neratinib is a potent irreversible pan-ErbB tyrosine kinase inhibitor, approved by the FDA for extended adjuvant treatment of HER2-positive breast cancer. Diarrhea is the most frequently observed adverse event with tyrosine kinase inhibitor therapy. In this study, we developed a reproducible model for neratinib-induced diarrhea in male and female rats.

METHODS

At first, male rats were treated with neratinib at 15, 30 or 50 mg/kg or vehicle control via oral gavage for 28 days (total n = 12). Secondly, we compared outcomes of male (n = 7) and female (n = 8) rats, treated with 50 mg/kg neratinib.

RESULTS

Rats treated with a 50 mg/kg daily dose of neratinib had a reproducible and clinically relevant level of diarrhea and therefore was confirmed as an appropriate dose. Male rats treated with neratinib had significant changes to their gut microbiome. This included neratinib-induced increases in Ruminococcaceae (P = 0.0023) and Oscillospira (P = 0.026), and decreases in Blautia (P = 0.0002). On average, female rats experienced more significant neratinib-induced diarrhea (mean grade 1.526) compared with male rats (mean grade 1.182) (P < 0.0001). Neratinib caused a reduction in percentage weight gain after 28 days of treatment in females (P = 0.0018) compared with vehicle controls. Females and males both showed instances of villus atrophy and fusion, most severely in the distal ileum. Serum neratinib concentration was higher in female rats compared to male rats (P = 0.043).

CONCLUSIONS

A reproducible diarrhea model was developed in both female and male rats, which indicated that diarrhea pathogenesis is multifactorial, including anatomical disruption particularly evident in the distal ileum, and alterations in microbial composition.

Neratinib in Early-Stage Breast Cancer: A Profile of Its Use in the EU

Neratinib (Nerlynx^®) is an oral, irreversible pan-human epidermal growth factor receptor (HER) tyrosine kinase inhibitor of HER1, HER2 and HER4. Neratinib therapy for 12 months significantly reduced the risk of invasive disease recurrence or death relative to placebo at both 2 and 5 years post-randomization in the pivotal ExteNET trial in women with early-stage HER2-positive breast cancer who had completed adjuvant trastuzumab. Subgroup analyses showed that patients with hormone receptor (HRc)-positive disease derived greater benefit with neratinib than patients with HRc-negative disease, and patients who initiated neratinib within 1 year of completing trastuzumab had better outcomes than those who started treatment 1–2 years after trastuzumab. This led to the approval of neratinib in the EU as extended adjuvant therapy for patients with early-stage HRc-positive, HER2-positive breast cancer and who are less than 1 year from completion of prior adjuvant trastuzumab-based therapy. It is the first agent of its class to be approved in the EU in this setting. As with other tyrosine kinase inhibitors, diarrhoea, which was manageable with antidiarrhoeal prophylaxis and/or dose modifications, was the most common any-grade or grade ≥ 3 treatment-emergent adverse event with neratinib. Thus, current evidence indicates that neratinib provides a valuable option to reduce the risk of recurrence in this setting and has been included in the updated ESMO patient guide as an extended adjuvant therapy for some patients.

Targeting neratinib-induced diarrhea with budesonide and colesevelam in a rat model

PURPOSE

Neratinib is an irreversible pan-ErbB tyrosine kinase inhibitor used for the extended adjuvant treatment of early-stage HER2-positive breast cancer. Its use is associated with the development of severe diarrhea in up to 40% of patients in the absence of proactive management. We previously developed a rat model of neratinib-induced diarrhea and found inflammation and anatomical disruption in the ileum and colon. Here we tested whether anti-diarrheal interventions, budesonide and colesevelam, can reduce neratinib-induced diarrhea and intestinal pathology.

METHODS

Rats were treated with 50 mg/kg neratinib via oral gavage for 14 or 28 days (total n = 64). Body weight and diarrhea severity were recorded daily. Apoptosis was measured using immunohistochemistry for caspase-3. Inflammation was measured via a multiplex cytokine/chemokine assay. ErbB levels were measured using PCR and Western Blot.

RESULTS

Budesonide co-treatment caused rats to gain significantly less weight than neratinib alone from day 4 of treatment (P = 0.0418). Budesonide (P = 0.027) and colesevelam (P = 0.033) each reduced the amount of days with moderate diarrhea compared to neratinib alone. In the proximal colon, rats treated with neratinib had higher levels of apoptosis compared to controls (P = 0.0035). Budesonide reduced histopathological injury in the proximal (P = 0.0401) and distal colon (P = 0.027) and increased anti-inflammatory IL-4 tissue concentration (ileum; P = 0.0026, colon; P = 0.031) compared to rats treated with neratinib alone. In the distal ileum, while budesonide decreased ErbB1 mRNA expression compared to controls (P = 0.018) (PCR), an increase in total ErbB1 protein was detected (P = 0.0021) (Western Blot).

CONCLUSION

Both budesonide and colesevelam show potential as effective interventions against neratinib-induced diarrhea.

Novel treatment strategies for patients with HER2-positive breast cancer who do not benefit from current targeted therapy drugs

Human epidermal growth factor receptor-2 positive breast cancer (HER2+ BC) is characterized by a high rate of metastasis and drug resistance. The advent of targeted therapy drugs greatly improves the prognosis of HER2+ BC patients. However, drug resistance or severe side effects have limited the application of targeted therapy drugs. To achieve more effective treatment, considerable research has concentrated on strategies to overcome drug resistance. Abemaciclib (CDK4/6 inhibitor), a new antibody-drug conjugate (ADC), src homology 2 (SH2) containing tyrosine phosphatase-1 (SHP-1) and fatty acid synthase (FASN) have been demonstrated to improve drug resistance. In addition, using an effective vector to accurately deliver drugs to tumors has shown good application prospects. Many studies have also found that natural anti-cancer substances produced effective results during in vitro and in vivo anti-HER2+ BC research. This review aimed to summarize the current status of potential clinical drugs that may benefit HER2+ BC patients in the future.

A Comprehensive Review of US FDA-Approved Immune Checkpoint Inhibitors in Urothelial Carcinoma

Few effective treatment options are available for patients with advanced or metastatic urothelial carcinoma (UC) after unsuccessful first-line platinum-based chemotherapy. To date, immune checkpoint inhibitors are novel therapeutic agents for UC treatment. From May 2016 to May 2017, five anti-PD-1/PD-L1 monoclonal antibodies received accelerated or regular approval from the US Food and Drug Administration (FDA) for the treatment of patients with locally advanced or metastatic UC. The present comprehensive review presents the background information of these five US FDA-approved anticancer agents to provide a basic but concise understanding of these agents for advanced studies. We summarize their immune checkpoint mechanisms, clinical efficacy, recommended usage protocols, adverse events, and the limitations of the PD-L1 biomarker assays.