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Innovative Immunotherapy Approach Boosts Treatment Success in Early-Stage Hormone Receptor-Positive/HER2-Negative Breast Cancer

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Mason Walker
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Innovative Immunotherapy Approach Boosts Treatment Success in Early-Stage Hormone Receptor-Positive/HER2-Negative Breast Cancer

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Recent advancements in immunotherapy have brought new hope for patients with early-stage hormone receptor (HR)-positive/HER2-negative breast cancer. Two randomized trials have shown promising results in increasing the rate of pathologic complete response (pCR), and reducing residual cancer burden (RCB). The trials support the significant impact of adding an immune checkpoint inhibitor (ICI) to chemotherapy in cases of high-risk early-stage breast cancer.

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Focusing on Pembrolizumab

One of the studies, the KEYNOTE-756 trial, focused on pembrolizumab, an immune checkpoint inhibitor. The researchers found that adding pembrolizumab to chemotherapy significantly increased the pCR rate and shifted the RCB to lower categories in patients with early-stage, high-risk ER-positive, HER2-negative breast cancer. This was observed regardless of the tumor's programmed death-ligand 1 (PD-L1) status. Patients in the study were stratified based on factors such as region, tumor PD-L1 status, nodal involvement, ER positivity, and anthracycline schedule. The results demonstrated a statistically significant improvement in pCR compared to placebo plus chemotherapy. The pembrolizumab plus chemotherapy combination also showed a statistically significant improvement in pCR versus placebo plus chemotherapy, with consistent results for secondary pCR definitions. Furthermore, in the neoadjuvant phase, grade 3 or higher treatment-related adverse event rates were 52.5% with pembrolizumab plus chemotherapy compared to 46.4% with placebo and chemotherapy.

Exploring Other Combination Therapies

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Other studies have also showed promising results with different drug combinations. For instance, the addition of tucatinib to trastuzumab emtansine (T-DM1) resulted in a median progression-free survival (PFS) of 9.5 months versus 7.4 months with placebo among patients with previously treated human epidermal growth factor receptor 2 (HER2)-positive, locally advanced or metastatic breast cancer. Similarly, the combination of tucatinib and T-DM1 showed a significant overall survival (OS) compared to chemotherapy alone.

Considerations for Treatment Selection

With the emergence of multiple antibody drug conjugate (ADC) options for patients with HER2 negative metastatic breast cancer, clinicians must carefully consider a variety of factors when selecting and sequencing therapies. For example, sacituzumab govitecan has recently been approved for the treatment of patients with unresectable locally advanced or metastatic hormone receptor positive HER2 negative breast cancer.

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Identifying Biomarkers

An exploratory analysis of the Neoadjuvant Carboplatin in Triple Negative Breast Cancer (NACATRINE) study aimed to identify biomarkers of pCR in patients with triple negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC) within the context of a clinical trial. The study identified gene expression alterations that predict the pathological complete response in triple negative breast cancer.

While these studies have significantly improved our understanding of the use of immunotherapy in early HR-positive/HER2-negative breast cancer, more data is needed, specifically event-free survival (EFS) data, to provide a more comprehensive view of the potential benefits. Nonetheless, these findings are crucial in refining the patient subpopulation with primary ER-positive/HER2-negative breast cancer who could potentially benefit from the addition of ICIs to neoadjuvant chemotherapy.

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