CMN Weekly (22 December 2023) - Your Weekly CRISPR Medicine News

Top picks

• Researchers from the Netherlands have shown that CRISPR-Cas9-induced loss of TP53 drives resistance to a large majority of drugs used to treat relapsed pediatric acute lymphoblastic leukaemia (ALL). However, a high-throughput drug screen identified the histone deacetylase inhibitor romidepsin as a potent sensitiser of drug responsiveness to cytarabine in TP53-deleted ALL cells in vivo. Since romidepsin has been approved for clinical use in some adult malignancies, these findings may be rapidly translated to clinical practice.

Research

• A study by Indian researchers shows that targeted hepatitis B virus X protein (HBx) gene editing by CRISPR-Cas9 is a potential novel therapeutic approach for HBV-induced hepatocellular carcinoma (HCC). A decreased expression of mesenchymal markers, proliferation and tumorigenic properties was observed after full-length excision of HBx in CRISPR-treated cells.
• An Iranian study on glioma cells utilised CRISPR-Cas9 to target the hTERT gene, which is crucial for telomerase activity and cancer cell survival. Enhanced transfection efficiency was achieved using sgRNA and Cas9 hybrids. Results showed reduced hTERT expression and telomerase activity in transfected cells, leading to increased apoptosis. This suggests that CRISPR-Cas9 can effectively inhibit glioma cell growth by diminishing hTERT function.
• A study by South Africa and Zambia researchers examined the genetic and pharmacological dependencies in human cancers, focusing on the "dark genome". It found that dark genes have high mutation rates in certain cancers and are crucial for patient survival outcomes, similar to light genes. The research highlights the therapeutic potential of targeting the dark genome in cancer treatment by analysing drug response and CRISPR-mediated gene knockouts.

Industry

• HuidaGene Therapeutics has been granted FDA Rare Pediatric Disease Designation for HG302, the first-ever CRISPR-Cas12 gene-editing therapy for Duchenne muscular dystrophy. The company's proprietary hfCas12Max is smaller than Cas9, thereby allowing it to be packaged using one viral vector with low off-targeting activity and high editing efficiency in mammalian cells.
• CRISPR Therapeutics' CMO, Phuong Khanh Morrow, resigns only six days after Casgevy's FDA approval. Her resignation was not the result of any disagreement with the gene-editing company, and the search for a new CMO has already started.

CRISPR screens

• Utilising CRISPR-Cas9, American researchers screened ~1900 human transcription factors (TFs) to identify those essential for neuronal differentiation. The study revealed that lacking ZBTB18 significantly impairs neuron development. This approach offers a robust method to pinpoint critical TFs in human cell differentiation.
• A CRISPR screen of druggable targets in small cell lung cancer (SCLC) has identified the ataxia telangiectasia mutated (ATM) gene inhibitor (AZD1390) as a radiosensitiser. AZD1390 markedly enhanced radiation therapy efficiency against SCLC, providing a novel pharmacologically tractable radiosensitising strategy for patients with SCLC.
• Researchers at the University of Lausanne, Switzerland, have used a genome-wide CRISPR-Cas9 screen to identify the Ras-related protein Rab5A as crucial for HEV RNA replication. Targeted silencing of Rab5A and related endosomal proteins notably reduced HEV RNA replication, as did pharmacological inhibition of Rab5A.

Detection

• Chinese researchers have established a sensitive bacterial quantification strategy based on the CRISPR-Cas12a system combined with magnetic covalent organic frameworks (MCOFs) and hybridisation chain reaction (HCR). The method worked in food samples and can quantify total bacteria in 50 min with a minimum detection concentration of 10 CFU/mL.
• A new CRISPR–Cas12a-mediated lateral flow assay for detecting the food-borne pathogen Salmonella typhimurium uses a hue-recognition lateral flow assay. The assay has a visual detection limit of 1 copy μL–1 within one hour and displays a high specificity toward salmonella in fresh chicken samples.
• Researchers in China have combined CRISPR-Cas12b-mediated trans-cleavage with cross-priming amplification, enabling one-pot detection in a single reaction of tuberculosis caused by Mycobacterium tuberculosis. The assay, TB One-Pot, exhibited a specificity of 96.7% and excels in speed, sensitivity, and practical requirements.
• Chinese researchers present a colourimetric, photothermal, and fluorescent triple-mode CRISPR-Cas biosensor for drug-resistance bacteria detection. The biosensor has the potential to detect various drug-resistant bacteria, demonstrating significant practical applicability.
• Chinese researchers introduce a new CRISPR-Cas13a-empowered nanotechnology for ultrasensitive nano-electrochemistry and bioanalysis. The method is suitable for single-cell and real human serum detection, and its general applicability was validated by addressing microRNA-141 and the SARS-CoV-2 RNA gene fragment.

Reviews

• Next-generation biological vector platforms for in vivo delivery of genome editing agents. This review examines promising biological-derived platforms to deliver DNA editing agents in vivo and the engineering thereof, encompassing potent viral-based vehicles, flexible protein nanocages, and mammalian-derived particles.
• Approaches to therapeutic gene editing in alpha-1 antitrypsin deficiency. This review lists five distinct gene therapy approaches developed for treating alpha-1 antitrypsin deficiency (AATD). Each approach is discussed, and a summary of a standard CRISPR-Cas9 targeting method is presented.

Perspectives

• The cancer research landscape is transforming by introducing novel mouse models utilising prime- and base-editing techniques. In a News & Views in Nature Biotechnology, Australian researchers summarise the findings of two recent studies that carefully examine the role of specific genetic variants in cancer.
• A perspective in Wired discusses how the recent approval of the first CRISPR-based therapy is just the beginning and that getting it to patients will be the next hurdle. So far, only nine centres across the US are currently offering Casgevy, which may limit who gets access to it. Another limitation is the harsh conditioning regimen required, including collecting stem cells and chemotherapy.
• Fierce Pharma reports that while Vertex Pharmaceuticals and CRISPR Therapeutics build out the launch of Casgevy, there are indications for solid demand and warnings of possible supply hitches. A University of California, San Francisco doctor has already accumulated a waiting list of 15 to 20 patients at his site.

News from CRISPR Medicine News

• On Monday, we brought an interview with two groups of American researchers who have tweaked the prime editing technology to permit the use of DNA instead of RNA as a template for editing. This change could alleviate some of the main limitations of prime editing by allowing higher efficiency and adaptability.