Unfortunately, the media often reports of cancer “breakthroughs” that are overhyped primarily because the conclusions are from studies done in mice or test tubes, and not human trials. However, for the past five years there were some genuine breakthroughs in cancer therapy (1). These breakthroughs are the result of using the power of the patient’s immune system to kill cancer cells – a theory that has been around for over a century. Our body is naturally equipped to remove abnormal cells, viruses as well as bacteria from our body. Clearly, this safeguard fails in patients that eventually get cancer; but in the last two decades, scientists have learned more about why some cancers can evade the immune system.
Research studies have shown that cancer cells can release molecules that block or kill the immune cells designed to kill the tumour. As a result of this research, drug companies went on to discover “Antibody Drugs” (such as, anti-PD-1 and anti-CTLA-4) that could prevent cancer cells from doing that. One of the biggest breakthroughs that used immunotherapy to fight cancer came in 2010 after a clinical trial for metastatic melanoma (the deadliest form of skin cancer) showed that the antibody-drug ipilimumab (anti-CTLA-4) quadrupled the number of surviving patients after 5 years (2). Unlike other cancer therapies, immunotherapy appears to have a long-lasting effect, which results in this long-term survival. The reason for this is that unlike chemotherapy, which kills cancer cells only during the course of the treatment, the immune system remembers how the cancer cells “looks like” compared to normal cells and it attacks any time the cancer tries to come back. The antibody-based therapy has been approved in US (in 2012) and Canada (in 2014) as first-line of treatment for malignant melanoma providing the first palpable success of immunotherapy. Many other successful human trials with these types of drugs in last few years spurred the development of a novel branch of cancer therapy: immunotherapy.
The antibody drug based immunotherapy holds great potential to fight cancer and other antibody-based drugs (checkpoint inhibitors) will be discovered with more preclinical research. Fortunately, in 2014 the Canadian federal government funded Biotherapeutics for Cancer Treatment (BioCanRx), which will investigate many aspects of immunotherapy. There will probably never be a single-drug cancer cure, but a combination of multiple therapies for an individual patient’s cancer. Immunotherapy will be one powerful weapon in this fight.
This article was written by Dan Cojocari. Dan is a PhD candidate in the Department of Medical Biophysics at the University Toronto. He studies how pancreatic cancer cells are able to survive in harsh tumor environments. To learn more about Dan and his research check out his bio on our members page.
- Scientists unleash the power of immunotherapy on stubborn cancers. The Globe and Mail, Jan 09, 2015.
- Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med. 2010 Sep 23;363(13):1290.