Therapeutic use of a popular gene editing technique may inadvertently increase the risk of cancer, according to a study.
Researchers from Karolinska Institutet, Sweden, and the University of Helsinki in Finland say that more studies are required in order to guarantee the safety of these 'molecular scissors' for gene-editing therapies.
CRISPR-Cas9 technique is a molecular machine first discovered in bacteria that can be programmed to go to an exact place in the genome, where it cuts the DNA.
These precise 'molecular scissors' can be used to correct faulty pieces of DNA and are currently being used in clinical trials for cancer immunotherapy in the US and China.
"CRISPR-Cas9 is a powerful tool with staggering therapeutic potential," said Bernhard Schmierer, a researcher at Karolinska Institute.
"Like all medical treatments however, CRISPR-Cas9-based therapies might have side effects, which the patients and care-givers should be aware of," Schmierer said.
New trials are expected to be launched soon to treat inherited blood disorders such as sickle cell anaemia, researchers said.
The new study, published in the journal Nature Medicine, found that therapeutic application of the genome-editing tool may, in fact, increase the risk of cancer.
In one of the studies, scientists found that use of CRISPR-Cas9 in human cells in a laboratory setting can activate a protein known as p53, which acts as a cell's 'first aid kit' for DNA breaks.
Once active, p53 reduces the efficiency of CRISPR-Cas9 gene editing. Thus, cells that do not have p53 or are unable to activate it show better gene editing.
However, lack of p53 is also known to contribute to making cells grow uncontrollably and become cancerous.
"By picking cells that have successfully repaired the damaged gene we intended to fix, we might inadvertently also pick cells without functional p53," said Emma Haapaniemi from Karolinska Institutet.
"If transplanted into a patient, as in gene therapy for inherited diseases, such cells could give rise to cancer, raising concerns for the safety of CRISPR-based gene therapies," Haapaniemi said.