October is dedicated to raising awareness about breast cancer and there are many more things healthcare professionals, health blogs and journals and even patients can do to participate in addition to wearing a pink ribbon. If you follow our blog you know that we at FindMeCure take updating our readership on treatments in development very seriously. Drugs and therapies under study are our hope for the future of healthcare, so taking the time to learn more about them is an investment in your future health as well as the background education you need to make informed decisions about your treatment. After all, how can you choose the best option for yourself if a whole world of opportunities remains unexplored? 

This Breast Cancer Awareness Month we’d like to talk about emerging areas in metastatic breast cancer treatment since clinical research has come so far in recent years. Although metastatic breast cancer remains incurable, we seem to be on the verge of a breakthrough that can significantly lengthen and improve the quality of life for patients. Treatments currently under investigation show a lot of promise and we want to share this valuable information with you because we believe hope is a crucial part of treatment. 

Blocking the division of cancerous cells

It follows that stopping cancer in its tracks is about blocking the growth, i.e. multiplication of its cells. There currently are drugs that do just that but now they’re in clinical trials for metastatic breast cancer as well. Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors interrupt the cell division by blocking (inhibiting) CDK4 and CDK6 enzymes. The FDA has approved Verzinio, Ibrance and Kisqali for the treatment of breast cancer (all three drugs are CDK4 and CDK6 inhibitors) but now other such inhibitors are being investigated for the treatment of metastatic breast cancer. 

CDK4/6 inhibitors are used alongside hormone therapy. You’ll hear a lot about HER2-targeted therapies but what are they? HER2 is a protein that plays an important role in cancer cell growth and is found on the surface of cancer cells in a very high quantity in about 10-20% of breast cancers. There are antibody drugs targetting those cells that are already FDA approved and there are antibody drugs still in trials. However, a combination of HER2-targeted antibody drugs and a chemotherapy drug can prove to be more potent. These antibody conjugates (drug combinations) are under investigation for metastatic cancer treatment because they can deliver chemotherapy to targeted cancer cells. 

Interrupting the cancer cells growth and function proved to be a great approach to treating metastatic breast cancer. Blocking tyrosine-kinase enzymes important for the proper functioning of cancer cells can stop the cell growth in its tracks at many different points of the cycle. Neratinib and tucatinib are such inhibitors being studied in metastatic breast cancer. 

PI3 kinase inhibitors are another class of drugs designed to stop the growth of cancer cells by interrupting the PI3 kinase signals. PI3 kinase is an enzyme controlled by the PIK3CA gene, a gene that is often mutated in breast cancer, which in turn causes the cancerous tumour to grow. 

An enzyme involved in DNA repair can be the key to making chemotherapy more effective. PARP inhibitors work by blocking the function of the PARP enzyme, thus preventing the repair of the tumour DNA. This way a chemotherapy drug that damages the DNA of the cancer cells has a higher chance of succeeding at killing the cells. However, this treatment is only suitable for a subgroup of breast cancer patients who have a BRCA1/2 gene mutation as cancers related to the mutation are more sensitive to this kind of DNA damage. 

Using the immune system against the cancer cells

Immunotherapy is already used for the treatment of different kinds of cancer. Employing the body’s own immune system against the tumour cells is a clever approach that proves to be highly successful in some cases, though research is continuously going on. 

In phase II clinical trial, led by Steven A. Rosenberg, M.D. from the National Cancer Institute (NCI), a new approach to immunotherapy showed promising results and the study findings were published in June 2018. This new approach takes a spin on ACT, adoptive cell transfer, which is a process of transferring cells into a patient. In the case of cancer treatment, often the cells come from the patient – the process includes T cells extraction, subsequent modification and then an infusion into the patient’s organism.

The angle that researchers are now focusing on is much more based on mutations, however, rather than the type of cancer the patient has. In the study, the team is using tumour-infiltrating lymphocytes (TILs) to target mutations in the tumour cells in order to shrink the tumours that ACT hasn’t been all that effective at treating.

The case that illustrates the new approach being developed is that of a metastatic breast cancer patient who came to the trial after trying everything else. The team sequenced DNA and RNA from her tumour and from healthy tissue to find out which unique to her case mutations they needed to target. Then they checked which of her TILs would recognize the mutated proteins.

The right TILs were multiplied and infused back into her. Her tumour consequently disappeared and she has been tumour-free for more than 22 months afterwards. Mutation-targeted TILs have a long way to go before their potential is confirmed in a larger study but so far the results from this one make us hopeful for the future of metastatic breast cancer treatment.

Checkpoint inhibitors are another type of immunotherapy currently under investigation for the treatment of metastatic cancer. Some kinds of cancer can protect themselves from being attacked by the immune system by stimulating proteins that keep the immune response in check. Checkpoint inhibitors remove the ‘brakes’ by blocking those proteins so that the immune system can target the cancer cells and kill them. 

Although this kind of immunotherapy has been more successful in cancers like melanoma and lung cancer, checkpoint inhibitors are being studied for their potential to treat metastatic breast cancer as well. 

All of these drugs and therapies are the result of continuous clinical research on breast cancer. Finding better treatments for the second most common kind of cancer is very important for researchers and medical professionals who want to improve healthcare and reach more patient on time. You can become a part of the process by joining a clinical trial, even an observational one, so we can have a better understanding of breast cancer and the possibilities for treatment.

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