International Journal of Clinical Case Reports 2024, Vol.14, No.3, 167-177 http://medscipublisher.com/index.php/ijccr 169 Despite its potential, CAR-T cell therapy faces challenges such as limited efficacy in solid tumors and severe side effects (Macri and Mintern, 2019). 2.1.3 Cancer vaccines Cancer vaccines aim to stimulate the immune system to recognize and attack cancer cells. These vaccines can be prophylactic or therapeutic. While therapeutic cancer vaccines have had limited success historically, recent advancements suggest potential when used in combination with other immunotherapies (Lohmueller and Finn, 2017). Prophylactic vaccines are also being developed to prevent cancer in high-risk populations (Lohmueller and Finn, 2017). 2.1.4 Monoclonal antibodies Monoclonal antibodies (mAbs) are laboratory-produced molecules that can bind to specific antigens on cancer cells. They can work through various mechanisms, including blocking growth signals, marking cancer cells for destruction by the immune system, and delivering cytotoxic agents directly to cancer cells. mAbs have been particularly effective in HER2-positive breast cancer, with drugs like trastuzumab significantly improving patient outcomes (Khalil et al., 2016; Agostinetto et al., 2022). 2.2 Mechanisms of action The mechanisms of action for breast cancer immunotherapies vary depending on the type of therapy. ICIs work by blocking inhibitory pathways that prevent T cells from attacking cancer cells, thereby enhancing the immune response (Esteva et al., 2019; Bagchi et al., 2020). CAR-T cell therapy involves the direct targeting and killing of cancer cells by engineered T cells (Khalil et al., 2016). Cancer vaccines stimulate the immune system to recognize and attack cancer cells, either by presenting cancer antigens or by enhancing the overall immune response (Lohmueller and Finn, 2017). Monoclonal antibodies can block growth signals, recruit immune cells to destroy cancer cells, or deliver cytotoxic agents directly to the tumor (Khalil et al., 2016; Adams et al., 2019). 2.3 Historical context and development The concept of using the immune system to fight cancer dates back over a century, but significant breakthroughs have only occurred in the past decade. The approval of the first immune checkpoint inhibitor, anti-CTLA-4, in 2011 marked a turning point in cancer immunotherapy (Macri and Mintern, 2019; Bagchi et al., 2020). Since then, numerous ICIs, CAR-T cell therapies, and monoclonal antibodies have been developed and approved for various cancers, including breast cancer (Khalil et al., 2016; Esteva et al., 2019). The development of these therapies has been driven by a deeper understanding of the immune system and its interactions with cancer cells, as well as advances in genetic engineering and biotechnology (Lohmueller and Finn, 2017; Macri and Mintern, 2019). 3 Case-Based Efficacy Analysis 3.1 Case 1: complete durable regression in metastatic breast cancers In a groundbreaking study by Zacharakis et al. (2018), the efficacy of adoptive cell transfer (ACT) utilizing tumor-infiltrating lymphocytes (TILs) was demonstrated in a patient with metastatic breast cancer. The patient, who had previously undergone extensive conventional treatments without significant success, exhibited a complete durable regression following ACT. The treatment involved the extraction, expansion, and reinfusion of TILs specifically targeting mutant proteins expressed by the tumor. Remarkably, the patient achieved a sustained remission, with no detectable cancer cells for an extended period post-treatment. This case underscores the potential of personalized immunotherapy approaches in achieving significant clinical outcomes in advanced metastatic breast cancers. 3.2 Case 2: neoadjuvant immunotherapy in triple-negative breast cancer Zhao et al. (2023) investigated the application of neoadjuvant immunotherapy in patients with triple-negative breast cancer (TNBC), a subtype notoriously resistant to conventional treatments. The study involved a combination of pembrolizumab, an immune checkpoint inhibitor, administered prior to surgical resection. The results were promising, with a significant proportion of patients achieving a pathological complete response (pCR), indicating no residual invasive cancer detectable in the breast or lymph nodes (Figure 2). This response is
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