New leukemia treatment involves a drug called ibrutinib, which is being tested on tumors that target the body’s immune system and if approved it could eventually replace chemotherapy.
In research published in the New England Journal of Medicine (NEJM), scientists report that the experimental drug, which differs from broadly acting chemotherapy agents by specifically targeting certain cancer-causing processes, significantly prolongs the life of patients.
Ibrutinib is currently being tested on tumors that target the body’s immune system, such as CLL and mantle cell lymphoma (MCL).
CLL is the second most common form of leukemia among adults in the U.S., and about 15,000 Americans, most of whom are elderly, are diagnosed with the blood and bone marrow cancer every year.
The drug is the first to bind to and block the activity of a protein known as Bruton’s tyrosine kinase (BTK), which plays an important role in helping immune cell tumors, which develop from abnormally growing blood stem cells, to grow.
Once ibrutinib binds to the immune system’s B-cells, it prevents tumors growing in these cells from signaling for the nutrients they need to grow and divide. According to the study, the drug doesn’t seem to affect the body’s T-cells, as chemotherapy agents do, so patients experience fewer side effects.
Early work on animals showed that the experimental drug effectively shut down tumor cell division, so the researchers tested the compound on 85 CLL patients who had all tried and failed to respond to at least two other anti-cancer treatments. Some even harbored genetic mutations associated with particularly aggressive forms of CLL that typically lead to death within two years of diagnosis.
The patients were randomized to take one of two different doses of an ibrutinib pill a day. After nearly two years of treatment, 71% of this hard-to-treat group had responded with slower tumor growth, and at 26 months, 75% showed no additional progression of their cancer. At the end of the study period, 83% of the participants were still alive, and most of the patients only complained of diarrhea and fatigue.