FDA Approves Ibrutinib

FDA Approves Ibrutinib

The US Food and Drug Administration (FDA) approved ibrutininb in November 2013 for the treatment of relapsed mantle cell lymphoma. Ibrutinib is a new drug which was developed to specifically block a particular enzyme called the Bruton’s tyrosine kinase which goes by the acronym, BTK. This enzyme, BTK, is over-active in many types of malignancies to include mantle cell lymphoma and chronic lymphocytic leukemia, CLL. Recent research has demonstrated remarkable response rates in patients with mantle cell lymphoma and CLL.

The exciting part of ibrutinib is that it is an oral medication with moderate side-effects. The clinical trial which lead to the approval was a multi-center, international study with 111 patients that had relapsed mantle cell lymphoma. The study demonstrated that the overall response rate was 66% with the average duration of response of 17.5 months. The most common toxicities were low blood counts, increased bruising, diarrhea, fatigue, muscle pain and rash. Only 9% of patients encountered a side-effect that lead to discontinuation of ibrutinib.

The enzyme, BTK, is a recently identified protein that was discovered in a variety of malignant cells that are derived from the B-cells. B-cells are a specific type of blood cell which normally produces antibodies to help the body fight infections. The B-cells can develop into cancer through a variety of mutations which cause the cells to grow more rapidly and survive longer than normally. The malignancies which may have a B-cell derivation include CLL, Non-Hodgkin lymphoma and Waldenstrom macroglobulinemia.

Bruton’s tyrosine kinase was first discovered in 1993 and is named after Ogden Bruton who first described a disordered called Bruton’s agammaglobulinemia. When the enzyme is not presnt the B-cells are not able to produce the antibodies needed to help the body fight off infections. If the B-cells become malignant, then by blocking or inhibiting this enzyme, BTK, the growth of the malignant cells can be halted.

There are many clinical studies which are ongoing that will define the role ibrutinib will have in early stages of CLL, Non-Hodgkin lymphoma and mantle cell lymphoma. It is hoped that by adding ibrutinib to current treatments available for these malignancies that improved responses and prolongation of survival of patients will be seen. This is a very promising drug and we at Green Bay Oncology are very excited to bring this news to you. Please feel free to give us a call for further information.