It is often difficult during cancer treatment to achieve a balance between getting rid of as many tumour cells as possible, while at the same time not causing serious side effects.
One of the common properties of tumour cells is that they grow rapidly and in an uncontrolled manner. The chemotherapy drugs that are used to treat cancer have for this reason been designed to kill rapidly growing cells. But the treatment also kills normal cells that grow rapidly. One of the more sensitive tissues is the bone marrow, where various types of blood cell are formed at a rapid rate. Approximately 25% of lung cancer patients who receive combination treatment with the drugs gemcitabine and carboplatin experience life-threatening side effects on the bone marrow during standard treatment. In many cases, the treatment must be discontinued.
We know that genetic factors play a role in the response of an individual to these treatments. Complicated interactions between many genes are probably involved. The scientists who carried out the study have therefore investigated whether genetic signatures exist that can be used to identify the patients at a high risk of experiencing severe side effects from the treatment. This would enable them to adapt treatment to the individual more accurately from the start: those with a low risk of side effects can be given higher doses, with a stronger effect on the cancer, while those with highest risk can be given another treatment.
The study, published in npj Systems Biology and Applications, is a collaboration between researchers in pharmacogenetics and bioinformatics. They determined the complete DNA sequences of 96 patients with non-small cell lung cancer who had been treated with gemcitabine/carboplatin. Sequencing of the whole genome in this way provides information about millions of genetic variants that may be interesting. The researchers wanted to see whether they could find in this huge amount of data functional groups of genes that were linked to the degree of toxicity that the treatment had had on the bone marrow of the different patients