Cervical cancer completely eliminated by CRISPR-Cas9 in mice
A new approach, utilizing lipid vesicles, successfully targeted genes of human papilloma virus (HPV) and completely cured mice from cervical cancer.
99.7% of cervical cancers are caused by persistent HPV infection. The virus essentially pastes its material into the human genome – and transformed cancer cells still depend on the viral genes called E6 and E7.
Gene therapy disrupting E6/E7 was proposed as early as ten years ago. However, the results were disappointing even in animal models. Moreover, experiments were sophisticated in terms of technology and administration.
The new approach relies on simple intravenous injections. Liposomes (lipid vesicles) shielded with a polyethylene-glycol layer (PEGylated) deliver CRISPR-Cas9 with high efficiency. In contrast to the most popular mean of delivery – harmless viruses – they do not elicit an immune response, allowing multiple injections, and they can carry a much larger payload.
5 mice with xenograft tumors (human cancer cells transplanted into animals) were treated with three injections separated by four days. After 77 days, 4 mice had no tumors present. Further experiments with various doses and types of cancer cells proved significant or, again, complete elimination of cancer disease.
Group leader, Nigel McMillan, concludes:
This treatment would be fantastic because we are targeting foreign genes, genes that are not normally in our genome. There are still many steps to go through before we get to the clinic stage, but I think this really proves that gene editing and CRISPR is going to be proved to be useful in the treatment of not only genetic disorders, but also cancer.
Publication: Jubair, L., Fallaha, S., & McMillan, N. A. (2019). Systemic Delivery of CRISPR/Cas9 Targeting HPV Oncogenes Is Effective at Eliminating Established Tumors. Molecular Therapy. Doi:10.1016/j.ymthe.2019.08.012.
Photo: National Cancer Institute