Genetic mutation assay brings personalised cancer treatment closer

DxS, the genotyping services company based in Manchester in the UK, claims to have taken a step closer to its goal of improving drug therapy by developing a diagnostic test which predicts response to anticancer drugs.

This follows the announcement by two leading US academic teams that they had identified a set of genetic mutations that correlated with response to AstraZeneca's lung cancer drug Iressa. This is a therapy that works very well, but only in a small proportion of patients. Now, scientists have discovered a group of mutations in epidermal growth factor receptor (EGFR) - the target for the drug - that explain a big part of this drug's activity.^1,2 Patients who acquire one of these mutations do extremely well on Iressa. Unfortunately, the mutations are quite rare, and only about 10% of patients show this response.

To allow this kind of testing in tandem with the use of Iressa and other drugs that target EGFR, such as Roche's Tarceva and Pfizer's CI-1033, there is a need for validated diagnostic assays. However, there is a complication with the type of testing needed for this application.

Because the mutations are found in the tumour they may constitute only a very small proportion of the total genetic material. For this reason any test must be very sensitive and able to detect low level mutations. DxS recently announced a licensing agreement with AstraZeneca to access the drugs giant's ARMS technology.

'ARMS is a very powerful method to detect under-represented mutations,' commented DxS's chief scientific officer, Dr David Whitcombe. 'When coupled with DxS's Scorpions detection system, we are able to detect mutations even when they comprise less than 1% of the total genetic material.'