T-cell gene therapy successful in early clinical trial

Researchers trialling a gene therapy-based treatment for leukaemia have said the results go beyond anything they could have hoped for in their 'wildest dreams'.

The therapy involves the genetic modification of a sufferer's white blood cells so that they are able to fight cancerous cells in the blood.

Researchers at the Memorial Sloan Kettering Cancer Center in New York, USA, performed the largest ever clinical trial of the technique on 16 leukaemia patients who had relapsed after chemotherapy treatment. Fourteen went into remission, comparing favourably with chemotherapy, which the researchers say is effective for just 30 percent of relapsed patients.

'We found that this type of therapy […] has outcomes that far exceed anything we could have thought or dreamed of in our wildest dreams', Dr Renier Brentjens, the study's lead author, told CBS New York. 'It's extremely gratifying to witness the astonishing results first hand'.

The study participants all had a type of cancer known as adult B-cell acute lymphoblastic leukemia (B-ALL), an aggressive cancer affecting a type of white blood cells known as B-cells.

For common viruses such as the flu, another type of white blood cell called T-cells fight the virus. But T-cells aren't able to detect cancerous cells affected in B-ALL, and so don't destroy them.

To overcome this problem, Dr Brentjens and his colleagues took a sample of each participant's T-cells. They then used gene therapy technology 'to redirect the immune cells to recognise [and destroy] the cancer', he told CBS New York.

The ultimate goal in the treatment of adult B-ALL is a bone marrow transplant, the only known cure for the disease. Without a successful transplant, most patients will die, but transplants can only be given to people whose cancer is in complete remission. T-cell gene therapy could therefore be a valuable option for those patients who have had no success with conventional therapies.

However the technique can cause significant side effects, including plummeting blood pressure, fevers, muscle pain and difficulties in breathing. Some patients are affected worse than others, and the study suggests diagnostic criteria that may help to identify who might be most vulnerable.

The study confirms the findings of a smaller trial on just five patients undertaken by the same research group (reported in BioNews 698). The therapy will need to be thoroughly tested in larger trials before it could become widely available, and this process will take several years.

The study was published in the journal Science Translational Medicine.