About Immunotherapies
Immunotherapies are designed to use a person's immune system to fight diseases, including cancer. Immunotherapies enable the immune system to target and destroy diseased cells and have far fewer side effects than other therapies, such as surgery, chemotherapy and radiation therapy. There are two types of immunotherapies used to treat cancer: passive immunotherapies and active immunotherapies.
Passive immunotherapies utilize large doses of infused antibodies that bind to antigens primarily expressed by a tumor cell and by few or no normal cells. These antibodies circulate throughout the bloodstream, binding to antigens on targeted cells, thereby flagging them for destruction. The most widely used passive immunotherapy for the treatment of B-cell non-Hodgkin's lymphoma is Rituxan®. Rituxan has demonstrated the ability to induce a clinical response – at least a 50% reduction in tumor burden – in approximately 50% of patients with indolent B-cell non-Hodgkin's lymphoma and with few side effects. In patients who respond to Rituxan, this response lasts from one to three years.
Despite their widespread use in fighting cancer, passive immunotherapies such as Rituxan suffer from significant limitations, including a limited duration of efficacy and the development of resistance. Additional passive immunotherapies have attempted to overcome the shortcomings of Rituxan by linking antibodies to radioactive molecules that can directly destroy the cell to which the antibody is bound. However, improvements in time to disease progression, if any, have been modest.
Active immunotherapies teach the patient's own immune system to recognize and fight cancer. Active immunotherapies are designed to program the immune system to generate a sustained and robust humoral and cell-mediated immune response. Favrille's lead product candidate, Specifid™ (formerly FavId®), for the treatment of B-cell non-Hodgkin's lymphoma is an active immunotherapy.
In the case of B-cell non-Hodgkin's lymphoma, the antibody protein made by a patient's B-cell non-Hodgkin's lymphoma is used as a target for immune attack. The unique antigens in this antibody protein are referred to as the idiotype. The immune system can differentiate between lymphoma cells and normal B-cells based on their idiotype. As a result, following successful idiotype immunotherapy, a patient's immune response is specific to their B-cell lymphoma.