Experimental drug found to slow progression of CLL

It has been confirmed that a specific molecule in the human body is important for the development of chronic lymphocytic leukaemia. A new study has confirmed that the molecule that is specifically targeted from a newly developed experimental drug is critical for the growth of the most common form of adult leukaemia.

The drug ibrutinib has shown a large amount of activity during clinical trials of patients suffering from chronic lymphocytic leukaemia (CLL). The medication targets the molecule Bruton's tyrosine kinase (BTK) by incapacitating it permanently. By stopping the BTK from working, the drug effectively shuts down a signal that it creates that promotes cancerous cell growth and spread.

Ibrutinib has also been found to inhibit other cells found within CLL called kinases, which may be important when it comes to the CLL cells surviving. This means that the drug could drastically improve patients' treatment when they are diagnosed with this type of cancer.

Dr Amy Johnson, associate professor of medicine in the division of hematology and principal investigator on the study, said: "Ibrutinib's lack of selectivity might mean that BTK is not the critical target in CLL, and that future drugs developed for CLL should focus on other molecules."

The study used CLL cells taken from human patients and two CLL mouse models. One of the models spontaneously developed a similar malignancy as occurs in some cases of human CLL. Researchers blocked the activity of BTK by using ibrutinib and also genetically. 

It was found that stopping the expression of BTK reduced the chances of the tumour cells surviving in 31 of the patients involved in the study. Researchers also discovered that the mouse model designed to have spontaneous CLL, the mice that were treated with the drug survived for a lot longer than control subjects did. Ibrutinib was also found to delay the onset of the cancer within the same the mouse model. 

Doctor Johnson said: "Overall, our findings validate BTK as a target for CLL therapy and strongly suggest that selective kinase-inhibitors might work in CLL like the drug imatinib does in chronic myeloid leukemia."