A new paper points to a previously unknown hurdle for scientists racing to develop therapies using the revolutionary genome-editing tool CRISPR-Cas9: the human immune system.
In a study posted Friday on the preprint site bioRxiv, researchers reported that many people have existing immune proteins and cells primed to target the Cas9 proteins included in CRISPR complexes. That means those patients might be immune to CRISPR-based therapies or vulnerable to dangerous side effects — the latter being especially concerning as CRISPR treatments move closer to clinical trials.
But researchers not involved with the study said its findings, if substantiated, could be worked around. (Papers are posted to bioRxiv before being peer-reviewed.) Many of the first planned CRISPR clinical trials, for example, involve removing cells from patients, fixing their DNA, and then returning them to patients. In that case, it’s possible that there will be few or no CRISPR proteins remaining for the immune system to detect.
They also noted that scientists are already studying other types of CRISPR that use different proteins, which could stave off the immune responses.