Genome Editing Anti-cancer System

Researchers at Tel Aviv University have demonstrated that the CRISPR/Cas9 system is very effective in treating metastatic cancers, a significant step on the way to finding a cure for cancer. The researchers developed a novel lipid nanoparticle-based delivery system that specifically targets cancer cells and destroys them by genetic manipulation. The system, called CRISPR-LNPs, carries a genetic messenger (messenger RNA), which encodes for the CRISPR enzyme Cas9 that acts as molecular scissors that cut the cells’ DNA.

Prof. Peer and his team chose two of the deadliest cancers: glioblastoma and metastatic ovarian cancer. Glioblastoma is the most aggressive type of brain cancer, with a life expectancy of 15 months after diagnosis and a five-year survival rate of only 3%. The researchers demonstrated that a single treatment with CRISPR-LNPs doubled the average life expectancy of mice with glioblastoma tumors, improving their overall survival rate by about 30%. Ovarian cancer is a major cause of death among women and the most lethal cancer of the female reproductive system. Most patients are diagnosed at an advanced stage of the disease when metastases have already spread throughout the body. Despite progress in recent years, only a third of the patients survive this disease. Treatment with CRISPR-LNPs in a metastatic ovarian cancer mice model increased their overall survival rate by 80%.

The whole scene of molecular drugs that utilize messenger RNA (genetic messengers) is thriving – in fact, most COVID-19 vaccines currently under development are based on this principle. There will be many personalized treatments based on genetic messengers (mRNA) – for both cancer and genetic diseases.

Remarkable progress has been made to improve the efficacy and safety of CRISPR-Cas9 gene editing. However, broad clinical translation will be enhanced by safe delivery systems able to edit efficiently specific diseased tissues in vivo. Because of the large size of the Cas9 nuclease, its encapsulation in both viral and nonviral delivery systems remains a challenge. Several approaches have been used to overcome the obstacle of delivering the large Cas9 nuclease as nucleic acid or protein for gene editing in the liver or locally for treating genetic disorders. These approaches achieved about 60% gene editing in the liver, resulting in reduced protein or cholesterol levels in the serum and alleviating disease symptoms in models of hemophilia, hypercholesterolemia, or TTR (transthyretin) amyloidosis. To date, systemic administration results in low editing efficiencies in extrahepatic tissues, partly due to the lack of specific targeting of current delivery vehicles. To achieve therapeutic effects for nonliver diseases or disseminated diseases, such as cancer, higher tissue-specific targeting with sufficient editing efficiencies is needed. Other genetic therapies, such as those based on RNA interference (RNAi), are transient and, therefore, would require repeated dosing, especially for rapidly dividing cancer cells. The permanent nature of genome editing should have a therapeutic impact even after one or a few doses, which could strongly affect toxicity, development of adverse reactions, compliance, and cost. Furthermore, the bacterial origin of the Cas9 nuclease renders it to be recognized by the host immune system and elicits an immune response. Long exposure time to the Cas9 nuclease, as well as repeating dosing, might increase the risk for Cas9-related immune responses following by immune-related adverse reactions and treatment failure. Therefore, to minimize this risk, delivery systems that could achieve therapeutic relevant genome editing with a limited number of administrations and short Cas9 exposure time must be developed.

In this study, we developed and tested an efficient nonviral LNP system for CRISPR-Cas9 gene editing, which showed gene editing of up to 98% in vitro in multiple cancer cell types and up to ~80% gene editing in vivo. cLNPs targeting PLK1 were able to inhibit tumor growth and improve survival in two aggressive cancer models in mice following single or double cLNP administrations. A single dose of sgPLK1-cLNPs to the tumor bed of a murine GBM model resulted in ~70% gene editing of the PLK1 gene, induced in vivo apoptosis as assessed by activated caspase 3 staining, prolonged median survival by ~50%, and improved overall survival of 005 GBM–bearing mice by 30%.

Science Advances – CRISPR-Cas9 genome editing using targeted lipid nanoparticles for cancer therapy

SOURCES- Tel Aviv, Science Advances
Written By Brian Wang,

Harnessing CRISPR-Cas9 technology for cancer therapeutics has been hampered by low editing efficiency in tumors and potential toxicity of existing delivery systems. Here, we describe a safe and efficient lipid nanoparticle (LNP) for the delivery of Cas9 mRNA and sgRNAs that use a novel amino-ionizable lipid. A single intracerebral injection of CRISPR-LNPs against PLK1 (sgPLK1-cLNPs) into aggressive orthotopic glioblastoma enabled up to ~70% gene editing in vivo, which caused tumor cell apoptosis, inhibited tumor growth by 50%, and improved survival by 30%. To reach disseminated tumors, cLNPs were also engineered for antibody-targeted delivery. Intraperitoneal injections of EGFR-targeted sgPLK1-cLNPs caused their selective uptake into disseminated ovarian tumors, enabled up to ~80% gene editing in vivo, inhibited tumor growth, and increased survival by 80%. The ability to disrupt gene expression in vivo in tumors opens new avenues for cancer treatment and research and potential applications for targeted gene editing of noncancerous tissues.