Breast Cancer: Current Research
Open Access

Immunotherapy; Breast cancer; Checkpoint inhibitors; Cancer vaccines; Adoptive cell therapy; Oncolytic virus therapy; Triple-negative breast cancer; Tumor microenvironment

Introduction

Breast cancer is one of the most prevalent cancers worldwide, affecting millions of women each year and remaining a leading cause of cancer-related deaths. Conventional treatment modalities, including surgery, chemotherapy, radiation, and targeted therapies, have significantly improved survival rates, especially when detected early. However, for patients with advanced-stage or aggressive subtypes, such as triple-negative breast cancer (TNBC), these treatments often fall short of achieving long-term remission or a cure. In this context, immunotherapy has emerged as a groundbreaking approach, offering new possibilities for durable responses and, potentially, a cure [1,2].

Immunotherapy aims to enhance the body's natural immune defenses to recognize and eliminate cancer cells more effectively. Unlike traditional therapies that directly target cancer cells, immunotherapy empowers the immune system to adapt and combat the evolving nature of cancer, offering the potential for more lasting and personalized treatment outcomes. The success of immunotherapy in other cancers, such as melanoma and lung cancer, has sparked significant interest in its application to breast cancer [3].

This article explores the landscape of immunotherapy in breast cancer, discussing the various strategies currently in development or clinical use. It examines the mechanisms by which immunotherapy works, highlights recent advancements in clinical trials, and addresses the challenges that limit its broader application in breast cancer. Through this exploration, we aim to understand how immunotherapy could pave the way toward a curative pathway for breast cancer [4].

Types of Immunotherapy in Breast Cancer

Checkpoint inhibitors: Immune checkpoint inhibitors are one of the most successful forms of immunotherapy to date. These drugs work by blocking proteins like PD-1, PD-L1, and CTLA-4, which cancer cells use to inhibit immune responses. By disrupting these pathways, checkpoint inhibitors help reinvigorate T cells to recognize and destroy cancer cells [5]. For instance, pembrolizumab (anti-PD-1 antibody) has shown promise in combination with chemotherapy for triple-negative breast cancer (TNBC), one of the most aggressive subtypes of breast cancer.

Cancer vaccines: Cancer vaccines aim to stimulate the immune system to attack specific cancer antigens. In breast cancer, vaccines targeting HER2-positive tumors, such as the NeuVax (nelipepimut-S) vaccine, have been explored in clinical trials [6]. These vaccines introduce antigens to the immune system, prompting an adaptive immune response that seeks out and destroys tumor cells expressing the target protein. Though early studies have shown mixed results, cancer vaccines hold potential as part of a combination therapy strategy.

Adoptive cell therapy: Adoptive cell therapy (ACT) involves the extraction, modification, and reinfusion of a patient’s immune cells to target cancer more effectively [7]. Chimeric antigen receptor (CAR) T-cell therapy, where T cells are engineered to express receptors that specifically target tumor antigens, has revolutionized treatment for blood cancers. In breast cancer, the development of CAR T cells targeting HER2-positive tumors is underway, though challenges remain in translating the success seen in hematologic malignancies to solid tumors [8].

Oncolytic virus therapy: Oncolytic viruses are engineered to selectively infect and kill cancer cells while stimulating an anti-tumor immune response. Talimogene laherparepvec (T-VEC), an oncolytic herpesvirus, has been explored in breast cancer treatment [9]. By lysing tumor cells and releasing cancer antigens into the microenvironment, oncolytic viruses help recruit immune cells to the tumor site. Although still in experimental phases, this approach represents a novel mechanism for engaging the immune system in breast cancer therapy [10].

Conclusion

Immunotherapy has ushered in a new era of hope for breast cancer treatment, particularly for patients with aggressive and treatment-resistant forms of the disease. By harnessing the immune system’s ability to recognize and eliminate cancer cells, immunotherapy offers a potential pathway toward achieving long-term remission and even a cure in some cases. Significant progress has been made with immune checkpoint inhibitors, cancer vaccines, adoptive cell therapy, and oncolytic viruses, particularly in subtypes like triple-negative breast cancer (TNBC).

However, challenges such as tumor heterogeneity, an immunosuppressive tumor microenvironment, and the development of resistance continue to limit the broader success of immunotherapy in breast cancer. Addressing these barriers through combination therapies, personalized treatment approaches, and ongoing research into novel immune targets is essential for advancing the field. Despite these hurdles, the future of immunotherapy in breast cancer remains promising, with continued innovation and clinical trials paving the way toward more effective and potentially curative treatments. As our understanding of the immune system's interaction with cancer deepens, immunotherapy may ultimately transform breast cancer treatment and offer new hope for patients worldwide.

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