Professor Gareth Morgan Chronic lymphocytic leukemia (CLL) is a variable disease that may be aggressive in some patients while others do not experience symptoms or require treatment. The Institute of Cancer Research (ICR) has now introduced a genetic test that can identify patients with the most common type of adult leukaemia who will not respond well to currently available drugs. It was also suggested that patients diagnosed with CLL should be tested for the presence of the TP53 gene mutation before starting any treatment.

CLL patients with the TP53 mutation probably are less likely to respond positively towards existing drugs and their five-year survival is much lower. Hence, such patients can be seemingly subjected to experimental treatments. If TP53 is functioning properly, this tumor suppressor gene can supposedly help avert the development of cancers by controlling DNA repair and cell division. Once TP53 is mutated, the process of programmed cell death purportedly fails and cells are able to multiply out of control.

“Testing for the TP53 mutation is the most accurate measure we have developed so far of predicting patients’ likely response to treatment. Identifying patients who are unlikely to benefit from standard treatment allows us to give these patients a better chance of survival by helping them join clinical trials for new therapies,” remarked senior author Professor Gareth Morgan from the ICR and The Royal Marsden.

While conducting the study, investigators scanned the DNA of cancer samples of 529 CLL patients who were a part of an earlier chemotherapy drug trial. Their genetic information was matched with the patients’ response to treatment and the length of time they survived. TP53 mutations were registered in 40 patients representing 7.6 percent of the study group.

These patients reportedly had a strong link between carrying the mutation and both failure to respond to treatment as well as poor survival. Approximately 83 percent of patients without the mutation and 27 percent patients with the mutation seemingly responded to existing drugs. Authors mention that one in five patients with the mutation was alive after five years, in comparison to three in five patients who did not carry the mutation.

The study is published in the Journal of Clinical Oncology.