Lung cancer protein could be a target for new therapy
Scientists have discovered a protein on the surface of cancerous lung cells that could be the target for a new therapy. Tests in mice showed that specific targeting of the protein with a pre-existing therapy reduced the size of tumours, prevented the spread of cancer and allowed mice with lung cancer to live longer.
The normal function of the protein, called CD22, is to allow cells to stick to the biological scaffold that surrounds cells in tissues. It is naturally present on some white blood cells involved in the immune system so its discovery on lung cancer cells was a bit of a surprise. However the surprise was a good one as the scientists studying CD22 had already developed a therapy to treat a different blood cancer that specifically targets the protein and delivers a toxic substance to the cell.
To test whether their therapy would also kill the lung cancer cells, mice with the cancer were given four weekly treatments of either the therapy, called HB22.7, or a placebo control. Tumours in the mice treated grew to only about half the size of those in the control mice.
Many cancers are fatal because they are able to spread throughout the body; the team wanted to test whether HB22.7 could prevent this deadly feature of cancer. They injected lung cancer cells into the bloodstream of treated and untreated mice. After four weeks of the chemotherapy treated mice had virtually no tumour growth in evidence, in fact, only one had microscopic evidence of a single lung tumour. Nine out of 10 mice treated lived to the end of the 87 day experiment whereas most of the control mice had died by day 14.
HB22.7 is a monoclonal antibody therapy like Herceptin, which is already commonly used to treat breast cancer. The researchers are now preparing HB22.7 for clinical trials to test safety and effectiveness in humans. Lung cancer is the most common cause of death from cancer in the UK for both men and women.