Stem cell treatment kills cancer cells that have spread in mice

A new stem cell-based cancer treatment can target and kill breast cancer cells that have spread in mice, according to a new study.

The researchers behind the work hope that, if it is shown to work in humans, the treatment could also help to prevent some of the side effects of chemotherapy.

Professor Laura Machesky, an expert at Cancer Research UK’s Beatson Institute, said that the promising technique could one day be useful for treatment and imaging.

The study by scientists at the University of California used stem cells that are usually found in bone marrow, but which travel to the site of cancers that have spread. 

Cancer spread, called metastasis, is generally much harder to treat than when it is found only at one site.

The stem cells were genetically engineered and given a piece of code that lets them produce a molecule when they reach a tumour site. This molecule switches on an inactive chemotherapy drug. 

“This new toxic drug won’t be activated without the stem cells, so other parts of the body should be left alone,” said Machesky.

The researchers transplanted the engineered stem cells into mice where breast cancer had spread to the lungs, and the stem cells were left to find the tumour site. The mice were also given the inactive drug. 

Once they reached the tumour site, the stem cells were triggered to produce the molecule, activating the chemotherapy. This killed both the cancer cells and also the stem cells, helping to reduce the drug’s toxicity. 

Regular chemotherapy can be successful in killing cancer cells, but it can also kill healthy cells. The new treatment only targets metastatic tissue and so the researchers hope that it might reduce side effects if trialled in patients.

“The approach does have some possible problems, including that the stem cells might go to other places in the body – in fact they do, but so far these researchers have not detected any side effects as a result,” added Machesky.

The team also hopes that the treatment might be used for other cancers.

“There are still some issues to be worked out but this might one day be a really promising technique for imaging and destroying cancer that’s spread.”

The study is published in the journal Science Translational Medicine.