Forty years ago, of all women diagnosed with breast cancer, about 70% went at least five years without having a relapse. Now that number is closer to 90%. This progress has been achieved, among other things, thanks to the understanding of the enormous diversity of this disease. Chemotherapy since the 1970s has demonstrated its ability to improve patient outcomes when applied after surgery. Hormonal treatments were added and later targeted therapies, effective against tumors overexpressing the HER2 protein, which gradually reduced the impact of breast cancer. However, there is a type of these tumors whose weaknesses are unknown, such as those that made earlier advances possible. Those called triple negative, because their cells do not have estrogen or progesterone receptors and produce little HER2, still have few therapeutic options. They represent about 15% of breast tumors, they are more common in women under 40, much more aggressive and have a poorer prognosis.
Hey, the magazine New England Journal of Medicine public the results of a study that offers a new treatment option to these patients. The trial, which involved 847 patients, showed that when an immunotherapy drug, pembrolizumab, is added to the usual treatment of these tumors, chemotherapy, the average survival increases by seven months in patients with triple-negative advanced cancer: from 16.1 months to 23. Seven months more overall survival than the authors of the study, led by Javier Cortés, director of the IBCC (International Breast Cancer Center) in Barcelona, consider a figure “very relevant”.
Experimental treatments are being tested in people with a weaker outlook, but will offer more benefit in patients with less advanced tumors
To achieve this benefit, trial leaders identified a marker with therapeutic utility. PD-L1 is a protein that our body uses to identify healthy cells and prevent our own immune system, in addition to eliminating harmful viruses or bacteria, from harming us. This protective function is also used by certain tumor cells, genuine malignant reverses of our normal being, to avoid being detected and destroyed by our defenses. The immunotherapeutic treatments, such as the monoclonal antibody pembrolizumab, used in this study, are able to remove this mask from the cancer and expose it to the immune system. 40% of people with triple-negative breast tumors have elevated levels of this biomarker and could benefit from the new treatment.
Sara López, medical oncologist at Gregorio Marañón Hospital and member of the geicam group of breast cancer research, considers the result important, and “not just because of the overall increase in survival”. “Between 2000 and 2017, with this group of patients, only a seven-month improvement was achieved, and that is very little. Immunotherapy, which has shown a response in many tumors, has barely done so in breast cancer,” says López, who was not involved in the study. “This will open the door to further exploration of immunotherapy for breast cancer and that is important,” he adds. Like all experimental treatments, they are tested in people with the least promise first, but will offer more noticeable benefits when applied to patients whose tumors are less advanced. “That’s where you can have a bigger impact and you already have,” insists López.
Javier Cortés recalls that the increase in survival at seven months recorded in the study “is the most significant in the history of metastatic triple negative breast cancer”, although he recognizes that it is necessary “to continue to investigate in order to continue to improve the quality of life and survival of these patients. In addition, this underlines the importance of having a marker such as PDL1 to continue to improve the classification of tumors which until now had little In the effort to gain ground against cancer, the classification of tumors is combined according to their characteristics and the possibilities offered by different drugs, alone or in combination, to stop them. will be important to combine trojans with immunotherapy. The former are drugs that combine a targeted drug to deliver chemotherapy to the tumor and release the load there with greater intensity and fewer side effects. Immunotherapy could also unmask tumors hidden under the expression of proteins such as PDL1 and increase the effectiveness of other drugs.
César Rodríguez, vice president of the Spanish Society of Medical Oncology (SEOM), agrees on the importance of the results. On the one hand, he states that, “although the additional seven months of survival may seem little to the public, the great advances in oncology are produced by adding seven months here and seven months there, until years of survival be reached”. Rodríguez, who is an oncologist at the University Hospital of Salamanca, also highlights the contribution of this work to precision medicine. “The study shows that people with higher expression of PDL-1 [alrededor del 40%] it benefits a lot, while those who don’t have this expression hardly benefit from it, ”he explains. “This will allow us to give treatment to patients who will really benefit from it, and avoid giving a potentially toxic and very expensive drug to those who do not need it,” he concludes.
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