Breast cancer is the most common cancer in women worldwide, with more than two million new cases diagnosed in 2018. There are various types of breast cancer, mainly classified on the basis of the expression of certain proteins, such as estrogen receptor (ER), progesterone receptor (PR) and Her2 (human epidermal growth factor receptor 2).
Drugs have been specifically designed to target these proteins to cancer cells. For example, in women with positive breast cancer, an ER is treated with a drug called Tamoxifen, which blocks the action of ER and gives hope to millions of women. Some breast cancers, however, do not express any of these three proteins (ER, PR or Her2) and are classified as Triple Negative Breast Cancer (TNBC).
TNBC is known to be an aggressive form of breast cancer, and those who suffer from this have a small chance of survival. It is more common in young women. This type of breast cancer accounts for approximately 15% of the total number of breast cancer cases. However, its incidence in India is higher (27.9%) compared with other regions of the world.
Traditionally, chemotherapy, which involves administering a number of drugs to prevent cancer cells from growing out of control, is the standard of care for TNBC. Despite treatment, TNBC patients show high rates of re-emergence of the disease, which, unfortunately, leads to premature death. Therefore, there is an urgent need for improved therapy in the treatment of TNBC.
Immunotherapy, which boosts the body's immune system, has shown promise for treating certain types of cancer and is now recognized as a potential therapeutic approach in TNBC. It uses its own body molecules or synthetic substances that strengthen or restore the immune system.
A newly developed type of immunotherapy uses a class of drugs called checkpoint inhibitors that use key surface molecules on T-cells, which are the main weapon of the immune system of the human body. James P. Ellison and Tasuku Honjo were awarded the Nobel Prize in Physiology and Medicine in 2018 for their work, which led to the discovery of new molecules that led to the development of immunotherapy.
A new study recently published in the New England Journal of Medicine (NEJM) by Dr. Peter Schmid of the Barca Cancer Institute, Queen Mary University of London and his colleagues, showed that combining immunotherapy with chemotherapy can improve the outcome for some advanced triple negative cancer patients. mammary gland.
Over 900 patients with untreated metastatic (where the cancer has spread to other parts of the body, such as the lungs) TNBC were included in a Phase III clinical trial and were randomized to receive Nab-Paclitaxel, a chemotherapeutic drug used to treat breast cancer, or with placebo ( without an immunotherapy drug) or in combination with Atezolizumab, a drug belonging to the class of inhibitors of the control point immunotherapy drugs.
In the body, immune T cells express a surface molecule, called PD-1, which can join another molecule, called PD-L1, present in other cells. This attachment transmits to T-cells that the other cell should not be destroyed and, therefore, prevents their attack on the immune system. Some cancer cells very skillfully use this in a Trojan horse style, having more PD-L1 molecules on their surface and, therefore, avoid an immune attack. The immunotherapy drug, Atezolizumab, works by blocking the PD-L1 molecules on cancer cells and thereby prevents them from transferring the wrong signals to immune cells.
However, this study has significant drawbacks. Combination therapy has been found to increase average survival to 25 months versus 15.5 months. But cancer cells should have a high level of PD-L1 molecules on their surface, which may not be the case in all patients. This means that before starting therapy, it is necessary to check the status of the PD-L1 receptor in patients.
In addition, it should be borne in mind that the side effects associated with combination therapy are more pronounced than single-agent chemotherapy. Also, the cost of such personalized immunotherapy can be extremely high, with one round of therapy being Rs. 1 lakh to 13 rupees.
Immunotherapy is still developing in developing countries, such as India, and is currently offered only in a few treatment centers, and also mainly for solid tumors such as the prostate, breast, kidney, colon, hepatocellular carcinoma, colorectal, oral, light and ovarian. Although this is only the first major clinical trial involving immunotherapy, more research is needed, positive results show a ray of hope for patients with TNBC.