New ‘killer’ stem cells could be used to treat cancer, say scientists

THE prospect of a major breakthrough in cancer treatment was announced by researchers yesterday who said they had 
created stem cells capable of killing diseased cancer cells for the first time.

Japanese scientists said they had made cancer-specific killer “T” cells, which could pave the way for them being injected into cancer patients to treat the ­disease.

Previous attempts to produce cells in this way have had limited success because they have had only a very short lifespan, restricting their use.

However, UK cancer experts said other methods were already being tested on patients and this latest “technical advance” was a long way from practical use.

Dr Hiroshi Kawamoto, who led the research, said of the results: “This strategy may solve the problem which the current immunotherapy strategies are facing, and thus would make a major breakthrough in cancer therapy.”

The team from the RIKEN Research Centre for Allergy and Immunology said they had created cancer-specific, immune system cells called killer T lymphocytes, from induced pluripotent stem cells (iPS) – those which have been artificially extracted from adult cells.

They achieved this by reprogramming T lymphocytes that specialise in killing a certain type of skin cancer, into iPS cells. This led to iPS cells to generate fully active, cancer-specific T lymphocytes, which could 
potentially be used for future cancer treatment.

The researchers, whose work is reported in the journal Cell Stem Cell, said previous research had shown that producing such cells in a laboratory using conventional methods had been inefficient in killing cancer cells, mainly because of their short lifespan.

Dr Kawamoto said: “The next step will be to test whether these T cells can selectively kill 
tumour cells but not other cells in the body.

“If they do, these cells might be directly injected into patients for therapy. This could be realised in the not-so-distant future.”

Cancer charities and experts gave the research a cautious welcome, but said a similar treatment method – adoptive T cell therapy – was further advanced.

This involves cells taken from patients being “souped up” and re-injected.

Dr Emma Smith, Cancer Research UK’s senior science information officer, said: “Boosting the body’s own immune system to attack cancers is an exciting field and this new research shows how scientists are making progress.

“But this work is still at a very early stage and was only carried out with cells in the lab. And as the researchers haven’t shown that these reprogrammed T cells can actually kill cancer cells in animals or humans, more research is needed to find out whether this approach will be safe and effective for treating ­patients.”

Professor Sir John Burn, of the Institute of Genetic Medicine at Newcastle University, said: “This is a very appealing concept and the research team are to be congratulated on demonstrating the feasibility of expanding these killer cells using iPS techniques.

“Headline writers need to beware that even if these T cells are effective, it could prove very challenging to produce large quantities safely and economically.

“Nevertheless, there is real promise of this becoming an alternative when conventional therapies have failed.”

Chris Mason, professor of Regenerative Medicine Bioprocessing at University College London, said: “For the next decade, the role of iPS cells in therapy is more likely to be in the fight against cancer than for permanent implantation to regenerate tissues and organs.

“The challenge is not their ability to function, but in proving their safety.

“The risk/benefit profile will take years to ­establish for permanently implanted iPS-
derived cells due to the complexity of their reprogramming.”