A team of scientists at The Institute of Cancer Research, London, used a technique called magnetic resonance spectroscopy (MRS) to watch the metabolic processes inside tumours, and to monitor the effects of experimental drug treatments.
MRS detects the magnetic signatures of different chemicals, giving researchers a view inside tumours without requiring invasive procedures like biopsy.
The method exploits the fact that tumours typically have abnormal metabolic activities. In particular, cancer cells often increase their glucose consumption and activate the process of anaerobic respiration. This enables them to meet the need for rapid growth and at the same time allows them to survive in the hostile low oxygen, nutrient-deprived environment within the tumour.
Anaerobic respiration produces the chemical lactate — more familiar to many as lactic acid, the cause of muscle pain during vigorous exercise. By measuring lactate levels with MRS, the researchers can watch anaerobic respiration happening in the tumour.
In their paper, published in the journal Cancer Research, the researchers demonstrated the method in melanoma treated with experimental targeted drugs called MEK inhibitors.
Although these drugs do not immediately kill cancer cells, they halt growth by interrupting a signalling pathway called RAF-RAS-MEK-ERK. This signalling pathway tells cells to grow and divide, and in many cancers it is abnormally active due to mutations — in the case of melanoma, to the BRAF component of the pathway.
Study lead Dr Mounia Beloueche-Babari, Staff Scientist at the ICR's Cancer Research UK & EPSRC Cancer Imaging Centre, said: "Because drugs like MEK inhibitors do not instantly kill the cancer cells and visibly shrink the tumour, we need methods that can show whether the treatments really are hitting their targets and halting progression of the disease. We were able to do that non-invasively using MRS to measure lactate production. MRS is clinically available, so lactate readouts could be useful for informing us on patients’ response to MEK or BRAF signalling inhibitors."
Professor Martin Leach, co-director of the Cancer Research UK & EPSRC Cancer Imaging Centre added: "These new techniques provide a way of confirming whether new treatments are acting on disease in the way intended, without the need for a biopsy."