A phase II randomised study of preoperative trastuzumab alone or combined with everolimus in patients with early HER2-positive breast cancer and predictive biomarkers (RADHER trial)

HER2-positive breast cancer: cotargeting to overcome treatment resistance

PURPOSE OF REVIEW

The introduction in clinical practice of anti-HER2 agents changed the prognosis of patients with HER2-positive (HER2+) breast cancer in both metastatic and early setting. Although the incomparable results obtained in the last years with the approval of new drugs targeting HER2, not all patients derive benefit from these treatments, experiencing primary or secondary resistance. The aim of this article is to review the data about cotargeting HER2 with different pathways (or epitopes of receptors) involved in its oncogenic signaling, as a mechanism to overcome resistance to anti-HER2 agents.

RECENT FINDINGS

Concordantly to the knowledge of the HER2+ breast cancer heterogeneity as well as new drugs, novel predictive biomarkers of response to anti-HER2 treatments are always raised helping to define target to overcome resistance. Cotargeting HER2 and hormone receptors is the most well known mechanism to improve benefit in HER2+/HR+ breast cancer. Additional HER2-cotargeting, such as, with PI3K pathway, as well as different HERs receptors or immune-checkpoints revealed promising results.

SUMMARY

HER2+ breast cancer is an heterogenous disease. Cotargeting HER2 with other signaling pathways involved in its mechanism of resistance may improve patient outcomes. Research efforts will continue to investigate novel targets and combinations to create more effective treatment regimes.

ONC201/TIC10 enhances durability of mTOR inhibitor everolimus in metastatic ER+ breast cancer

The mTOR inhibitor, everolimus, is an important clinical management component of metastatic ER+ breast cancer (BC). However, most patients develop resistance and progress on therapy, highlighting the need to discover strategies that increase mTOR inhibitor effectiveness. We developed ER+ BC cell lines, sensitive or resistant to everolimus, and discovered that combination treatment of ONC201/TIC10 with everolimus inhibited cell growth in 2D/3D in vitro studies. We confirmed increased therapeutic response in primary patient cells progressing on everolimus, supporting clinical relevance. We show that ONC201/TIC10 mechanism in metastatic ER+ BC cells involves oxidative phosphorylation inhibition and stress response activation. Transcriptomic analysis in everolimus resistant breast patient tumors and mitochondrial functional assays in resistant cell lines demonstrated increased mitochondrial respiration dependency, contributing to ONC201/TIC10 sensitivity. We propose that ONC201/TIC10 and modulation of mitochondrial function may provide an effective add-on therapy strategy for patients with metastatic ER+ BCs resistant to mTOR inhibitors.

Appraisal of Systemic Treatment Strategies in Early HER2-Positive Breast Cancer-A Literature Review

BACKGROUND

The overexpression of the human epidermal growth factor receptor 2 (HER2+) accounts for 15-20% of all breast cancer phenotypes. Even after the completion of the standard combination of chemotherapy and trastuzumab, relapse events occur in approximately 15% of cases. The neoadjuvant approach has multiple benefits that include the potential to downgrade staging and convert previously unresectable tumors to operable tumors. In addition, achieving a pathologic complete response (pCR) following preoperative systemic treatment is prognostic of enhanced survival outcomes. Thus, optimal evaluation among the suitable strategies is crucial in deciding which patients should be selected for the neoadjuvant approach.

METHODS

A literature search was conducted in the Embase, Medline, and Cochrane electronic libraries.

CONCLUSION

The evaluation of tumor and LN staging and, hence, stratifying BC recurrence risk are decisive factors in guiding clinicians to optimize treatment decisions between the neoadjuvant versus adjuvant approaches. For each individual case, it is important to consider the most likely postsurgical outcome, since, if the patient does not obtain pCR following neoadjuvant treatment, they are eligible for adjuvant T-DM1 in the case of residual disease. This review of HER2-positive female BC outlines suitable neoadjuvant and adjuvant systemic treatment strategies for guiding clinical decision making around the selection of an appropriate therapy.

Evaluating everolimus for the treatment of breast cancer

INTRODUCTION

Everolimus is an oral drug that inhibits mTOR with immunosuppressive and antiproliferative characteristics. It is commonly used in association with exemestane in hormone receptor (HR)-positive advanced breast cancer (ABC).

AREAS COVERED

The current review summarizes the publications relating to everolimus from clinical research in breast cancer. Everolimus showed treatment efficacy and an acceptable safety tolerance with prevention of side effects in Phase II/III studies. BOLERO-2 study showed a progression-free survival improvement in patients with HR-positive ABC previously treated with aromatase inhibitors (AI) and leading to its acceptance in this indication. The absence of a post CDK4/6 inhibitor (CDK4/6i.) study and the arrival of new drugs may raise questions about its current place in the therapeutic strategy.

EXPERT OPINION

Everolimus is relevant in the management of HR-positive ABC. Because of its efficacy, acceptable tolerability and the absence of drugs that have shown a greater benefit, it remains a second-line treatment option in HR-positive, HER2 negative (score 0) patients without BRCA mutation or visceral crisis and can be discuss with fulvestrant in second line after CDK4-6i. It is likely that within 5 years this treatment will be replaced in second line HR-positive breast cancer by new emerging treatments: drug-conjugated antibodies, tyrosine kinase inhibitors or immunotherapy in combination with chemotherapy.

Self-Assembled Nanodelivery System with Rapamycin and Curcumin for Combined Photo-Chemotherapy of Breast Cancer

Nanodelivery systems combining photothermal therapy (PTT) and chemotherapy (CT), have been widely used to improve the efficacy and biosafety of chemotherapeutic agents in cancer. In this work, we constructed a self-assembled nanodelivery system, formed by the assembling of photosensitizer (IR820), rapamycin (RAPA), and curcumin (CUR) into IR820-RAPA/CUR NPs, to realize photothermal therapy and chemotherapy for breast cancer. The IR820-RAPA/CUR NPs displayed a regular sphere, with a narrow particle size distribution, a high drug loading capacity, and good stability and pH response. Compared with free RAPA or free CUR, the nanoparticles showed a superior inhibitory effect on 4T1 cells in vitro. The IR820-RAPA/CUR NP treatment displayed an enhanced inhibitory effect on tumor growth in 4T1 tumor-bearing mice, compared to free drugs in vivo. In addition, PTT could provide mild hyperthermia (46.0 °C) for 4T1 tumor-bearing mice, and basically achieve tumor ablation, which is beneficial to improving the efficacy of chemotherapeutic drugs and avoiding damage to the surrounding normal tissue. The self-assembled nanodelivery system provides a promising strategy for coordinating photothermal therapy and chemotherapy to treat breast cancer.

Novel Treatments of Uveal Melanoma Identified with a Synthetic Lethal CRISPR/Cas9 Screen

Simple Summary

We performed a CRISPR-Cas9 synthetic lethality screen in order to identify molecular targets whose inhibition would synergistically enhance the effect of everolimus in uveal melanoma cells. IGF1R and PRKDC, among others, were identified as hits. We verified these hits effects genetically: we treated the uveal melanoma cell lines depleted of PRKDC or IGF1R with everolimus and, in case of IGF1R, observed a synergistic effect. Additionally, we found synergistic growth inhibition with the inhibitors targeting DNA-PKcs or IGF1R in combination with everolimus. Moreover, we investigated the combination of targeted inhibitors of DNA-PKcs and IGF1R with everolimus on uveal melanoma in an in vivo model. The dual DNA-PKcs/mTOR inhibitor CC-115 demonstrated activity in vivo.

Abstract

Currently, no systemic treatment is approved as the standard of care for metastatic uveal melanoma (UM). mTOR has been evaluated as a drug target in UM. However, one of the main limitations is dose reduction due to adverse effects. The combination of everolimus with another targeted agent would allow the reduction of the dose of a single drug, thus widening the therapeutic window. In our study, we aimed to identify a synergistic combination with everolimus in order to develop a novel treatment option for metastatic UM. We exploited CRISPR-Cas9 synthetic lethality screening technology to search for an efficient combination. IGF1R and PRKDC and several other genes were identified as hits in the screen. We investigated the effect of the combination of everolimus with the inhibitors targeting IGF1R and DNA-PKcs on the survival of UM cell lines. These combinations synergistically slowed down cell growth but did not induce apoptosis in UM cell lines. These combinations were tested on PDX UM in an in vivo model, but we could not detect tumor regression. However, we could find significant activity of the dual DNA-PKcs/mTOR inhibitor CC-115 on PDX UM in the in vivo model.

MUC1 is a potential target to overcome trastuzumab resistance in breast cancer therapy

Although resistance is its major obstacle in cancer therapy, trastuzumab is the most successful agent in treating epidermal growth factor receptor 2 positive (HER2 +) breast cancer (BC). Some patients show resistance to trastuzumab, and scientists want to circumvent this problem. This review elaborately discusses possible resistance mechanisms to trastuzumab and introduces mucin 1 (MUC1) as a potential target efficient for overcoming such resistance. MUC1 belongs to the mucin family, playing the oncogenic/mitogenic roles in cancer cells and interacting with several other oncogenic receptors and pathways, such as HER2, β-catenin, NF-κB, and estrogen receptor (ERα). Besides, it has been established that MUC1- Cytoplasmic Domain (MUC1-CD) accelerates the development of resistance to trastuzumab and that silencing MUC1-C proto-oncogene is associated with increased sensitivity of HER2⁺ cells to trastuzumab-induced growth inhibitors. We mention why targeting MUC1 can be useful in overcoming trastuzumab resistance in cancer therapy.