Novel antibody may slow tumour growth, spread: study

Washington: Scientists have developed an antibody that may potentially suppress lung tumour growth and breast cancer spread.

Researchers at the Johns Hopkins University School of Medicine in US developed the antibody against a specific cellular gateway that suppresses lung tumour cell growth and breast cancer metastasis in transplanted tumour experiments in mice.

The antibody, dubbed Y4, targets a potassium channel called KCNK9. Most commonly found in brain tissue and overabundant in lung, breast and other tumour cells, KCNK9 is among many gate like proteins that work to establish an electrical gradient that controls the flow of essential chemical ions, such as potassium in and out of cells that need them to function.

KCNK9's exact role in cancer is unclear, but scientists believe it helps tumour cells survive, grow and invade normal tissue.

"Our experiments do not predict how well the antibody would perform in cancer patients," said John Laterra, co-director of the Brain Cancer Programme at the Johns Hopkins Kimmel Cancer Centre.

"But the study points the way towards targeting this key channel in human cancers, particularly since KCNK9 is overexpressed in about 40 per cent of breast and lung cancers," he said.

Y4 was developed in the laboratory by Min Li, formerly of the Johns Hopkins Medicine and now at GlaxoSmithKline, by injecting mice with a human version of the KCNK9 protein to generate specialised cells that produce the KCNK9 specific antibodies.

When the researchers added Y4 to KCNK9-expressing human breast and lung cancer cells grown in the laboratory, the antibody reduced the cells' growth by between 25 to 65 per cent, and triggered cell death in three of the cancer cell
lines by between 5 and 30 per cent.

In further tests of the antibody, the scientists found that Y4 could slow the growth of human lung cancer cells transplanted into mice by up to 70 per cent.

The antibody did not shrink the lung cancer tumours or completely halt their growth. The drug also decreased the number of lung metastases in mice injected with mouse breast cancer cells, from an average of 30 metastases to an average of five after 25 days of treatment.

Laterra and colleagues also observed that the more KCNK9 is expressed in a tumour, the poorer the survival rates for lung and breast cancer patients.

They found that two-year survival rates for 35 people with squamous cell lung cancer with low levels of KCNK9 were 58 per cent higher than 18 people with high levels.

Ten-year survival rates for people with breast cancer were 10 per cent higher in 175 patients with low KCNK9 levels, compared with 116 people with high levels of the channel.

The study was published in the journal Nature Communications.