28 June 2013
Researchers in the US have developed a new, more streamlined screening process that can identify genetic changes in tiny fragments of protein which only exist in melanoma cells.
The new approach to screening has been outlined in an online article published by Nature Medicine and could have wide-ranging implications for melanoma cancer treatment.
The starting point is certain type of white blood cell known as a lymphocyte. It is known that some types of lymphocytes can penetrate certain forms of tumour, including melanoma, and have even been found to reduce cancerous lesions. The researchers believe that once the protein fragments have been identified, they can be used as targets for these tumour-infiltrating lymphocytes.
A higher concentration of these cells than usual suggests that the body is producing an immune response to fight the tumour. Counting the tumour-infiltrating lymphocytes and associating that information with the different characteristics of tumours, as well as potential outcomes, has been an important research area for various forms of cancer.
A phase 2 clinical trial carried out beforehand treated melanoma patients with their own tumour-infiltrating lymphocytes, and found that metastatic lesions - cancerous tumours that have spread to other areas of the body - regressed by a substantial amount in up to seven out of ten patients.
“The trial, which involved the adaptive transfer of a patient’s own immune cells, showed a complete tumor regression lasting at least five years in nearly 40 percent of the patients,” said Jamie K. Teer, PhD, assistant member of the Cancer Biology and Evolution Programme at Moffitt Cancer Center, which conducted the research.
According to Dr Teer, more detailed knowledge of exactly how tumour-infiltrating lymphocytes bring about the regression in cancer cells should help health researchers to make patient-donated cell therapy much more effective. But it could potentially go even further, revealing mechanisms of tumour growth that have not yet been discovered.
The new screening technique uses cutting-edge DNA sequencing technology to detect changes in a patient’s genetic coding which create the unique protein fragments, indicating melanoma in the process. As Dr Teer explained, the new technique “allowed us to more quickly and easily identify mutated gene antigens recognized by T-cells in the immune system".
“Work such as this was previously done by generating and laboriously screening DNA libraries from tumors. The same screening technique may be applicable for identifying mutated antigens in a variety of tumor types,” said Dr Teer.
In another study published last week (June 20th) in Cancer Cell, an international team of researchers described a new therapy that they found could be able to treat advanced melanoma.
Tumours start as a single cell but soon divide and grow until they consist of numerous different types of mutated cell. The scientists, headed up by Professor Colin Goding from the Ludwig Institute for Cancer Research and Professor José Neptuno Rodriguez-Lópex from the University of Murcia, explain that their therapy uses one of the mechanisms by which these cells mutate. Preclinical studies found that this new method was specific to melanoma cells and worked against tumours that resisted other therapies.
Posted by Jeanette Royston
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