A new drug approved by the United States Food and Drug Administration on March 25, 2011 is the first to successfully fight cancer by blocking an immune-inhibitory pathway. This approach is totally different from conventional chemotherapy's mechanism of killing cells as they divide. The new drug is ipilimumab, brand name Yervoy, from Bristol Meyers Squibb. What it does is analogous to taking the brakes off the immune system, so that the patient's own body can launch a full-scale assault on the cancer.
Ipilimumab was approved for unresectable or metastatic melanoma. In clinical trials, it improved the median survival time from 6 months to 10 months. This is far from a complete cure, but it is an important step in the search for immunotherapy agents for cancer. Other drugs with similar mechanism of action are in clinical trials for a variety of cancer types. One is tremelimumab from Pfizer, which passed its first test for tolerability in advanced breast cancer. Ipilimumab also caused regression of metastatic kidney cancer in a clinical trial.
Conventional chemotherapies cause side effects such as nausea and hair loss because they attack rapidly dividing cells and are not specific enough for cancer cells. Immunotherapies have very different side effects, similar to autoimmune conditions. A goal of immunotherapy research is to adjust the treatment so that the immune system can kill the cancer cells without too much damage to other tissue. Corticosteroids are used to manage side effects including rash, itching, and diarrhea.
According to The New York Times (March 26, 2011), the price for a full course of ipilimumab is $120,000. Patients who meet specific conditions can still join ongoing clinical trials. See http://clinicaltrials.gov/ct2/results?term=ipilimumab.
1. Peggs KS et al, “Ipilimumab: attenuation of an inhibitory immune checkpoint improved survival in metastatic melanoma”, Expert Rev Anticancer Ther. 2010 Nov.; 10(11): 1697-701.
2. Khan S et al, “Tremelimumab (anti-CTLA4) mediates immune responses mainly by direct activation of T effector cells rather than by affecting T regulatory cells”, Clin Immunol.