Radiation therapy and immunotherapy in breast cancer treatment: preliminary data and perspectives

Molecular Changes in Breast Cancer Induced by Radiation Therapy

PURPOSE

Breast cancer treatments are based on prognostic clinicopathologic features that form the basis for therapeutic guidelines. Although the utilization of these guidelines has decreased breast cancer-associated mortality rates over the past three decades, they are not adequate for individualized therapy. Radiation therapy (RT) is the backbone of breast cancer treatment. Although a highly successful therapeutic modality clinically, from a biological perspective, preclinical studies have shown RT to have the potential to alter tumor cell phenotype, immunogenicity, and the surrounding microenvironment, potentially changing the behavior of cancer cells and resulting in a significant variation in RT response. This review presents the recent advances in revealing the complex molecular changes induced by RT in the treatment of breast cancer and highlights the complexities of translating this information into clinically relevant tools for improved prognostic insights and the revelation of novel approaches for optimizing RT.

METHODS AND MATERIALS

Current literature was reviewed with a focus on recent advances made in the elucidation of tumor-associated radiation-induced molecular changes across molecular, genetic, and proteomic bases. This review was structured with the aim of providing an up-to-date overview over the very broad and complex subject matter of radiation-induced molecular changes and radioresistance, familiarizing the reader with the broader issue at hand.

RESULTS

The subject of radiation-induced molecular changes in breast cancer has been broached from various physiological focal points including that of the immune system, immunogenicity and the abscopal effect, tumor hypoxia, breast cancer classification and subtyping, molecular heterogeneity, and molecular plasticity. It is becoming increasingly apparent that breast cancer clinical subtyping alone does not adequately account for variation in RT response or radioresistance. Multiple components of the tumor microenvironment and immune system, delivered RT dose and fractionation schedules, radiation-induced bystander effects, and intrinsic tumor physiology and heterogeneity all contribute to the resultant RT outcome.

CONCLUSIONS

Despite recent advances and improvements in anticancer therapies, tumor resistance remains a significant challenge. As new analytical techniques and technologies continue to provide crucial insight into the complex molecular mechanisms of breast cancer and its treatment responses, it is becoming more evident that personalized anticancer treatment regimens may be vital in overcoming radioresistance.

Tolerance of Concurrent Adjuvant Radiation Therapy and Pembrolizumab for Triple Negative Breast Cancer: Real Life Experience

Purpose

The current standard-of-care management of locally advanced triple negative breast cancer (TNBC) is based on neoadjuvant chemo-immunotherapy with pembrolizumab, surgery, radiation therapy (RT), and adjuvant pembrolizumab. However, the safety of combining pembrolizumab with adjuvant breast RT has never been evaluated. This study evaluated the tolerance profile of concurrent pembrolizumab with adjuvant RT in patients with locally advanced TNBC.

Methods and Materials

This bicentric ambispective study included all the patients with early and locally advanced TNBC who received neoadjuvant chemo-immunotherapy with pembrolizumab and adjuvant RT as part of their treatment. The tolerance profile of adjuvant RT was evaluated and compared in patients who received concurrent pembrolizumab and in patients for whom pembrolizumab was withheld.

Results

Fifty-five patients were included between July 2021 and March 2023. Twenty-eight patients received adjuvant RT with concurrent pembrolizumab (RT+P group), and 27 patients had pembrolizumab withheld while receiving adjuvant RT (RT-only group). Two patients developed grade ≥3 toxicity (1 grade 3 pain in the RT+P group and 1 grade 3 radiodermatitis in the RT-only group), and there were no differences in terms of toxicity between the RT-only and the RT+P groups. No cardiac or pulmonary adverse event was reported during RT. With a median follow-up of 12 months (10-26), no patient relapsed.

Conclusions

In this study of limited size, the authors did not find a difference between the RT-only and RT+P groups in terms of toxicity. More studies and longer follow-up may add to the strength of this evidence.

[Radiotherapy and targeted therapy for the management of breast cancer: A review]

The purpose of this study was to review the current knowledge regarding combinations of the most commonly used targeted therapies or those under development for the management of breast cancer with radiation therapy. Several studies have shown that the combination of radiation therapy and tamoxifen increased the risk of radiation-induced lung toxicity; therefore, the two modalities are generally not given concurrently. The combination of HER2 inhibitors (trastuzumab, pertuzumab) and radiation therapy appeared to be safe. However, trastuzumab emtansine (T-DM1) should not be given concomitantly with brain radiation therapy because this combination may increase the risk of brain radionecrosis. The combination of radiation therapy with other new targeted therapies such as new selective estrogen receptor modulators (SERDs), lapatinib, cell cycle inhibitors, immune checkpoint inhibitors, or molecules acting on DNA damage repair seems feasible but has been mainly evaluated on retrospective or prospective studies with small numbers of patients. Moreover, there is a great heterogeneity between these studies regarding the dose and fractionation used in radiotherapy, the dosage of systemic treatments and the sequence of treatments used. Therefore, the combination of these new molecules with radiotherapy should be proposed sparingly, under close monitoring, pending the ongoing prospective studies cited in this review.

Vaccines in Breast Cancer: Challenges and Breakthroughs

Breast cancer is a problem for women's health globally. Early detection techniques come in a variety of forms ranging from local to systemic and from non-invasive to invasive. The treatment of cancer has always been challenging despite the availability of a wide range of therapeutics. This is either due to the variable behaviour and heterogeneity of the proliferating cells and/or the individual's response towards the treatment applied. However, advancements in cancer biology and scientific technology have changed the course of the cancer treatment approach. This current review briefly encompasses the diagnostics, the latest and most recent breakthrough strategies and challenges, and the limitations in fighting breast cancer, emphasising the development of breast cancer vaccines. It also includes the filed/granted patents referring to the same aspects.

Challenges in the combination of radiotherapy and immunotherapy for breast cancer

INTRODUCTION

Immunotherapy (IT) is showing promise in the treatment of breast cancer, but IT alone only benefits a minority of patients. Radiotherapy (RT) is usually included in the standard of care for breast cancer patients and is traditionally considered as a local form of treatment. The emerging knowledge of RT-induced systemic immune response, and the observation that the rare abscopal effect of RT on distant cancer metastases can be augmented by IT, have increased the enthusiasm for combinatorial immunoradiotherapy (IRT) for breast cancer patients. However, IRT largely follows the traditional sole RT and IT protocols and does not consider patient specificity, although patients' responses to treatment remain heterogeneous.

AREAS COVERED

This review discusses the rationale of IRT for breast cancer, the current knowledge, challenges, and future directions.

EXPERT OPINION

The synergy between RT and the immune system has been observed but not well understood at the basic level. The optimal dosages, timing, target, and impact of biomarkers are largely unknown. There is an urgent need to design efficacious pre-clinical and clinical trials to optimize IRT for cancer patients, maximize the synergy of radiation and immune response, and explore the abscopal effect in depth, taking into account patients' personal features.

The emerging role of PPAR-alpha in breast cancer

Breast cancer has been confirmed to have lipid disorders in the tumour microenvironment. Peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcriptional factor that belongs to the family of nuclear receptors. PPARα regulates the expression of genes involved in fatty acid homeostasis and is a major regulator of lipid metabolism. Because of its effects on lipid metabolism, an increasing number of studies have investigated the relationship of PPARα with breast cancer. PPARα has been shown to impact the cell cycle and apoptosis in normal cells and tumoral cells through regulating genes of the lipogenic pathway, fatty acid oxidation, fatty acid activation, and uptake of exogenous fatty acids. Besides, PPARα is involved in the regulation of the tumour microenvironment (anti-inflammation and inhibition of angiogenesis) by modulating different signal pathways such as NF-κB and PI3K/AKT/mTOR. Some synthetic PPARα ligands are used in adjuvant therapy for breast cancer. PPARα agonists are reported to reduce the side effects of chemotherapy and endocrine therapy. In addition, PPARα agonists enhance the curative effects of targeted therapy and radiation therapy. Interestingly, with the emerging role of immunotherapy, attention has been focused on the tumour microenvironment. The dual functions of PPARα agonists in immunotherapy need further research. This review aims to consolidate the operations of PPARα in lipid-related and other ways, as well as discuss the current and potential applications of PPARα agonists in tackling breast cancer.

Combinatorial Strategies With PD-1/PD-L1 Immune Checkpoint Blockade for Breast Cancer Therapy: Mechanisms and Clinical Outcomes

As an emerging antitumor strategy, immune checkpoint therapy is one of the most promising anticancer therapies due to its long response duration. Antibodies against the programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) axis have been extensively applied to various cancers and have demonstrated unprecedented efficacy. Nevertheless, a poor response to monotherapy with anti-PD-1/PD-L1 has been observed in metastatic breast cancer. Combination therapy with other standard treatments is expected to overcome this limitation of PD-1/PD-L1 blockade in the treatment of breast cancer. In the present review, we first illustrate the biological functions of PD-1/PD-L1 and their role in maintaining immune homeostasis as well as protecting against immune-mediated tissue damage in a variety of microenvironments. Several combination therapy strategies for the combination of PD-1/PD-L1 blockade with standard treatment modalities have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including chemotherapy, radiotherapy, targeted therapy, antiangiogenic therapy, and other immunotherapies. The corresponding clinical trials provide valuable estimates of treatment effects. Notably, several combination options significantly improve the response and efficacy of PD-1/PD-L1 blockade. This review provides a PD-1/PD-L1 clinical trial landscape survey in breast cancer to guide the development of more effective and less toxic combination therapies.

Implantable Bioresponsive Hydrogel Prevents Local Recurrence of Breast Cancer by Enhancing Radiosensitivity

Breast cancer is one of the most common types of cancer. Patients are often concerned about regional recurrence after breast cancer surgery. Radiotherapy plays a vital role in reducing recurrence and prolonging the survival of patients undergoing breast-conserving surgery and high-risk mastectomy. However, 8–15% of patients still have disease progression due to radiation resistance. Therefore, new strategies for combination radiotherapy sensitization must be investigated. In this study, an implantable drug loading system, sunitinib nanoparticles @ matrix metalloproteinases -response hydrogel (NSMRH), uses enzyme-sensitive hydrogel as a carrier to load sunitinib nanoparticles, was identified. The releasing profile demonstrated that sunitinib nanoparticles may be continuously released from the hydrogels. Functional experiments revealed that, when paired with NSMRH, radiation may significantly inhibit tumor cell proliferation, migration, and invasion in vitro. Further animal experiments showed that NSMRH combined with radiotherapy could more effectively control the recurrence of subcutaneous xenograft tumors, prolong the survival time, and have no obvious toxicity in nude mice. Finally, by studying the molecular mechanism of NSMRH, it was hypothesized that in breast cancer cells, NSMRH cooperated with sensitized radiotherapy, mainly due to significantly blocking the G2/M phase, reducing the DNA repair efficiency, inhibiting tumor angiogenesis, promoting apoptosis, and reversing the abnormal expression of platelet-derived growth factor receptor alpha (PDGFRA) after radiotherapy. These findings suggest that NSMRH’s radiation sensitization and anti-tumor activity may aid in the development of a novel method in future clinical applications.

Combination of Modern Radiotherapy and New Targeted Treatments for Breast Cancer Management

Simple Summary

Since the introduction of hormone therapy for the treatment of breast cancer (BC) three decades ago, many new targeted therapies have been developed. Some of them are currently used, such as HER2 inhibitors, while others are still under development, such as cell cycle (CDK) inhibitors, immune checkpoint (PD1/PDL1) inhibitors, or molecules acting on DNA damage (PARP) repair. Besides this, radiation therapy (RT) is commonly used either as adjuvant treatment for early BC after breast conservative surgery or in palliative intent for the treatment of metastatic sites. Our research has shown that the combinations of the most commonly used targeted treatments and RT were feasible with a few toxicities. Nevertheless, most of the knowledge on this subject is based on retrospective studies and a small number of patients and care should be taken in this setting until these results would be confirmed in prospective randomized studies.

Abstract

Background: The objective of the present study was to review the essential knowledge about the combinations of the most commonly used or under development targeted treatments and radiation therapy (RT). Methods: Preclinical and clinical studies investigating this combination were extensively reviewed. Results: Several studies showed that the combination of RT and tamoxifen increased the risk of radiation-induced pulmonary toxicity; therefore, both modalities should not be given concomitantly. The combination of HER2 inhibitors (trastuzumab, pertuzumab) and RT seems to be safe. However, trastuzumab emtansine (T-DM1) should not be administered concurrently with brain RT since this combination could increase the risk of brain radionecrosis. The combination of RT and other new target treatments such as selective estrogen receptor degradants, lapatinib, cell cycle inhibitors, immune checkpoint inhibitors, or molecules acting on DNA damage repair seems feasible but was essentially evaluated on retrospective or prospective studies with a small number of patients. Furthermore, there is considerable heterogeneity among these studies regarding the dose and fractionation of radiation, the dosage of drugs, and the sequence of treatments used. Conclusions: The combination of RT with most targeted therapies for BC appears to be well-tolerated, but these results need to be confirmed in prospective randomized studies.

Therapeutic Associations Comprising Anti-PD-1/PD-L1 in Breast Cancer: Clinical Challenges and Perspectives

Despite a few cases of long-responder patients, immunotherapy with anti-PD-(L)1 has so far proved rather disappointing in monotherapy in metastatic breast cancer, prompting the use of synergistic therapeutic combinations incorporating immunotherapy by immune-checkpoint inhibitors. In addition, a better understanding of both the mechanisms of sensitivity and resistance to immunotherapy, as well as the immunological effects of the usual treatments for breast cancer, make it possible to rationally consider this type of therapeutic combination. For several years, certain treatments, commonly used to treat patients with breast cancer, have shown that in addition to their direct cytotoxic effects, they may have an impact on the tumor immune microenvironment, by increasing the antigenicity and/or immunogenicity of a "cold" tumor, targeting the immunosuppressive microenvironment or counteracting the immune-exclusion profile. This review focuses on preclinical immunologic synergic mechanisms of various standard therapeutic approaches with anti-PD-(L)1, and discusses the potential clinical use of anti-PD-1/L1 combinations in metastatic or early breast cancer.

A phase I trial of sorafenib with whole brain radiotherapy (WBRT) in breast cancer patients with brain metastases and a correlative study of FLT-PET brain imaging

PURPOSE

Sorafenib has demonstrated anti-tumor efficacy and radiosensitizing activity preclinically and in breast cancer. We examined sorafenib in combination with whole brain radiotherapy (WBRT) and explored the [18F] 3'deoxy-3'-fluorothymidine (FLT)-PET as a novel brain imaging modality in breast cancer brain metastases.

METHODS

A phase I trial of WBRT + sorafenib was conducted using a 3 + 3 design with safety-expansion cohort. Sorafenib was given daily at the start of WBRT for 21 days. The primary endpoints were to determine a maximum tolerated dose (MTD) and to evaluate safety and toxicity. The secondary endpoint was CNS progression-free survival (CNS-PFS). MacDonald Criteria were used for response assessment with a correlative serial FLT-PET imaging study.

RESULTS

13 pts were evaluable for dose-limiting toxicity (DLT). DLTs were grade 4 increased lipase at 200 mg (n = 1) and grade 3 rash at 400 mg (n = 3). The MTD was 200 mg. The overall response rate was 71%. Median CNS-PFS was 12.8 months (95%CI: 6.7-NR). A total of 15 pts (10 WBRT + sorafenib and 5 WBRT) were enrolled in the FLT-PET study: baseline (n = 15), 7-10 days post WBRT (FU1, n = 14), and an additional 12 week (n = 9). A decline in average SUVmax of ≥ 25% was seen in 9/10 (90%) of WBRT + sorafenib patients and 2/4 (50%) of WBRT only patients.

CONCLUSIONS

Concurrent WBRT and sorafenib appear safe at 200 mg daily dose with clinical activity. CNS response was favorable compared to historical controls. This combination should be considered for further efficacy evaluation. FLT-PET may be useful as an early response imaging tool for brain metastases.

TRIAL AND CLINICAL REGISTRY

Trial registration numbers and dates: NCT01724606 (November 12, 2012) and NCT01621906 (June 18, 2012).