Immunotherapy, new era of cancer treatment

There is currently a lack of therapeutic solutions for metastatic cancers. During the last two American Society of Clinical Oncology (ASCO) congresses in 2014 and 2015, immunotherapy was presented as a real hope of stabilization and even remission, for some patients. “Strategies using the immune system against the tumor are considered huge scientific breakthroughs,” noted the prestigious industry journal, Science (December 2013). “It’s not about targeting the tumor only, anymore, but to arm the immune system.”
Today, traditional approaches such as surgery, chemotherapy, radiotherapy and targeted therapies treat between 50% and 60% of cancers. But the issue is very different, depending on whether the cancer is localized or metastatic.

Treatments based on immune defenses represent a new weapon in the fight against cancer, most especially, advanced cancers.

Using OSE Immunotherapeutics’ optimized, multi-epitope combination, which is capable of arming the body’s T cytotoxic cells against several tumor antigens, making them visible on malignant cells, the company has been able to elicit a T specific immune response in advanced, invasive cancers.

Immune defenses against cancer

The body’s immune system identifies tumor cells as “unknown” elements, and triggers a response involving a set of cells (lymphocytes and antigens presenting cells – APC) and specialized proteins. The coordinated action of all of these elements results in the destruction of malignant cells – and this is the cancer immunosurveillance process.

This response is characterized by two levels of defense. The first is non-specific – the innate immune system. The second, called the acquired adaptative immune system, is specific and capable of memory. This specificity is due to an activation process, during which certain lymphocytes learn to identify tumor antigens via their epitopes.

The epitope is a fragment of a tumor associated antigen called an “antigenic determinant.” It is a very small structure and a real “protein code” which is fixed to its cellular receptors. It is this epitope which triggers the body’s immune response.

That said, this defense system can be circumvented. Indeed, there are some tumor cells which present few characteristics betraying their nature – they are neither identified, nor attacked, by the immune system. They present tumor associated antigens but since these antigens are also present on other healthy organs, the immune response won’t activate against these “self-antigens.” They won’t be identified as unknown elements. Other malignant cells can also set up escape strategies. For instance, they will multiply rapidly and pass any potential response from the immune system. Some tumor associated antigens are even able to prevent the immune system from working by disrupting it and blocking the immunosurveillance.
Compared to today’s existing treatments, the combination of specific and non-specific immunotherapy products seems consistent and complementary to most experts, when considering methods to improve the efficiency and long term effect of various treatment regimens. Therapeutic combinations are common in oncology – they aim at maximizing effects and acting on several levels to halt the tumor cells’ escape.
Current research focuses on the development of specific molecules as well as non-specific molecules.
Using new molecules with non-specific T cytotoxic action, such as “checkpoint inhibitors,” or specific molecules, has shown stabilization of tumor growth in evaluated patients.