Immunotherapy improves overall survival of the most aggressive breast cancer

IBCC Barcelona study shows 27% improvement when pembrolizumab is added to chemotherapy

An international study has shown that adding a type of immunotherapy, pembrolizumab, to first-line chemotherapy improves the overall survival of patients with advanced triple-negative breast cancer with PD- expression by 27%. L1. This is the KEYNOTE-355 study and it was led by two researchers from the International Breast Cancer Center (IBCC) in Barcelona. The first results of this study were presented in 2020. The latest study reveals that the median overall survival for patients who received chemotherapy and pembrolizumab was 23 months and 16.1 months in the group who received chemotherapy plus placebo. .

Triple-negative breast cancer accounts for approximately 15% of all diagnosed breast tumours.

The first author of the work, Javier Cortés, explained that, until now, it had not been possible to improve overall survival in advanced triple-negative breast cancer with treatment based on immunotherapy, such as this is now done with pembrolizumab. Cortés stressed that this is very relevant news because this type of cancer is currently the one with the worst prognosis.

It is characterized by the absence of expression of estrogen and progesterone receptors, as well as the absence of overexpression of the human epidermal growth factor receptor 2 (HER2), which makes hormonal treatments and therapies directed against HER2, which have shown good results in other tumours. subtypes, are ineffective. Its biological aggressiveness and lack of treatment make it the breast tumor with the worst overall survival when the patient is in the advanced stage of the disease.

Pembrolizumab is a type of immunotherapy consisting of a monoclonal antibody directed against PD-L1 and a biomarker indicating that the defenses are slowed down. Pembrolizumab is responsible for lifting this brake and allows the defenses to be able to act against the tumor. To know the levels of PD-L1, a biopsy is performed or the tissue of the primary tumor is analyzed and the result is available in seven days. If the brake is not activated, other therapeutic strategies are used and, if it is activated, immunotherapy is added to the chemotherapy treatment.

The KEYNOTE-355 phase III study was conducted in 209 centers in 29 countries and included a total of 847 patients with advanced triple-negative breast cancer, whether or not they expressed the PD-L1 biomarker. These patients had received no prior therapy for metastatic disease. A total of 566 patients received chemotherapy and pembrolizumab and 281 received chemotherapy plus placebo.

Currently, and after a follow-up of 44.1 months, the study also showed that adding pembrolizumab to chemotherapy treatment increases overall survival statistically significantly by almost seven months in patients with breast cancer. triple-negative advanced breast with PD-L1 expression. . Median overall survival for patients receiving chemotherapy plus pembrolizumab was 23 months and 16.1 months for the chemotherapy plus placebo group.

The authors conclude that, in patients with advanced triple-negative breast cancer whose tumors express the biomarker PD-L1, the addition of pembrolizumab to chemotherapy in women resulted in significantly longer overall survival than chemotherapy. only. According to Cortés, about 40% of patients with triple-negative breast cancer have elevated levels of this biomarker.

The study was published The New England Journal of Medicine .

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