The anti-cancer immune response is as complex as is cancer itself. It is highly unlikely that one agent alone is sufficient to generate an effective anti-cancer immune response. Not only does CTLA-4 help tumors to suppress the immune response against them, PD-1 also plays an important role. It has already been shown in clinical trials that the combination of anti-CTLA-4 and anti-PD-1 inhibitors is significantly more effective than either one alone. Just recently the FDA has added approvals of this combination for certain melanoma, kidney and colon cancers. Unfortunately, just as success increases, so does the cost and side effects of the two drugs just as significantly. This is one reason that we inject the medications into the tumor microenvironment, where they need to be. You want the immune response to be directed against the tumor, and where that is more likely to occur is at the tumor site.
Once the immune system “learns” how to respond in one location, it is better able to attack cancer elsewhere in the body. In addition, a treatment such as cryoablation, which is the direct freezing of the tumor, has its own immune-stimulating properties. It can be considered an additional form of immunotherapy to be used with immune checkpoint inhibitors. And because ablation is minimally invasive and tumors are treated with a needle under image guidance, it is the perfect opportunity to administer other immune agents, such as the checkpoint inhibitor drugs, directly into the tumor, at the same time, in one procedure. Throughout the history of modern medicine, we have found many remarkable powerhouse treatment combinations. A great example is the treatment of HIV/AIDS. Just a few decades ago, an HIV diagnosis was a terminal one. But the current medications used today in combination have had great success and patients can live long, relatively normal lives with their disease. But when these same drugs are used alone, there is only a modest survival increase. Hence, the lessons we have learned in treating HIV patients supports the importance of combination therapy in treating disease, and cancer is no different. Immune checkpoint inhibitors not only help unlock a natural immune response, they can be essential for helping other immune therapies turn from bust to boom. It’s that synergistic immune response that enables cancer treatments to become far more effective than ever before. While our knowledge of immunotherapy is still developing, we have finally reached a point where cancer patients—like former President Jimmy Carter—can recover from malignant and fast-growing tumors previously thought hopeless. And when I talk about hope, I’m not talking about just passively sitting back and hoping for a cure. I’m talking about taking charge of the recovery process by doing everything possible to give the immune system a fighting chance against cancer.
Reference: Jason R. Williams, 15 Oct 2019, The Immunotherapy Revolution: The Best New Hope For Saving Cancer Patients’ Lives, https://williamscancerinstitute.com/the-immunotherapy-revolution