CMN Weekly (7 July 2023) - Your Weekly CRISPR Medicine News

Top picks

• He Jiankui, the Chinese scientist recognised for his controversial gene-editing trials on human embryos, has proposed a plan to modify human embryos by gene editing to confer protection against Alzheimer's disease. The proposal outlines Jiankui's plans to conduct gene-editing trials on mouse embryos and human zygotes to discern whether the particular A673T mutation in the APP gene could offer protection against Alzheimer's disease.
• CRISPR prime editing has been used for the unconstrained correction of oncogenic KRAS variants in HEK293T/17 cells. Researchers from South Korea developed universal pegRNAs, which can correct all G12 and G13 oncogenic KRAS mutations with CRISPR-mediated prime editors (PEs). The universal pegRNA successfully corrected 12 types of KRAS mutations, accounting for 94% of all known KRAS mutations, by up to 54.8% correction frequency.

Research

• To reduce the risk of fratricide in CAR-T therapies, Chinese researchers have used CRISPR-Cas9-targeted gene knockout to insert an EF1α-driven CD7-specific CAR at the disrupted CD7 locus. EF1α-driven CAR expressed at the CD7 locus reduced fratricide and enhanced tumour rejection in a mouse xenograft model of T-cell acute lymphoblastic leukaemia (T-ALL).
• An American research team led by Jennifer Doudna has demonstrated genome editing in the mouse brain through transient delivery of minimally immunogenic CRISPR-Cas9 ribonucleoproteins (RNPs). Results demonstrated that the transient Cas9 RNPs showed comparable editing of neurons and reduced adaptive immune responses relative to one formulation of Cas9 delivered using AAV9.
• A new deep learning model named TIGER (Targeted Inhibition of Gene Expression via guide RNA design) can predict on-target and off-target activity of CRISPR–Cas13d gRNAs. The model is so precise that it can be used to modulate transcript expression by selecting gRNAs with specific mismatches and thereby tune transcription of a target gene to, for example, 70%.
• Chinese researchers have used CRISPR-Cas9 to repair the point mutation R286W of the CLCN7 gene in osteopetrosis-specific iPSCs (ADO2-iPSCs) by homologous recombination. Osteopetrosis represents a rare genetic disease with a wide range of clinical and genetic heterogeneity resulting from osteoclast failure.
• American researchers have developed a novel platform, Combinatorial RNA Engineering via Scaffold Tagged gRNA (CREST), which simultaneously executes multiple RNA modulation functions on different RNA targets. In CREST, RNA scaffolds are appended to the 3' end of Cas13 gRNA, and their cognate RNA binding proteins are fused with enzymatic domains for manipulation. Further improvements in the design reduced nearly 99% of off-target events.
• German researchers have used chemical evolution of amphiphilic xenopeptides for potentiated Cas9 ribonucleoprotein delivery. The optimised amphiphilic carriers enabled ∼88% eGFP knockout at an RNP dose of only 1 nM and up to 40% homology-directed repair (HDR) in eGFP/BFP switchable reporter cells by co-delivery with an ssDNA template.
• Researchers in Italy have used CRISPR-Cas9 to disrupt HER-2-specific CD39 in T cells. The engineered T cells demonstrated a functional advantage in eliminating HER-2+ patient-derived organoids in vitro and in vivo. Accordingly, they might be promising advanced medicinal products for primary and metastatic colorectal cancers.
• American researchers present an engineered hypercompact CRISPR-Cas12f system with boosted gene-editing activity. enAsCas12f shows higher DNA cleavage activity than wild-type AsCas12f in vitro and functions broadly in human cells, delivering up to 69.8% insertions and deletions at user-specified genomic loci. It has minimal off-target editing activity and is only one-third of the size of SpCas9.
• Using a bicomponent CRISPR-based approach, researchers in the USA have developed a genetic population suppression system termed Ifegenia (Inherited Female Elimination by Genetically Encoded Nucleases to Interrupt Alleles) in the malaria vector Anopheles gambiae. Ifegenia males with a disrupted female-essential gene, femaleless (file), remain reproductively viable and can load both file mutations and CRISPR machinery to induce file mutations in subsequent generations, resulting in sustained population suppression.
• Researchers in Iran have developed a CRISPR-based strategy against cervical cancers related to human papillomavirus (HPV) type 16. Cas9 and gRNA sequences targeting HPV16 E5, E6, E7, and the p97 promoter were delivered to tumour cells or mice inoculated with tumour cells. Based on the tumour size reduction and IHC results, the outlook for precise gene therapy in cancer patients seems bright.

Industry

• Pfizer has invested $25M in Caribou Biosciences as part of the Pfizer Breakthrough Growth Initiative (PBGI), a program focused on funding promising clinical development programs of potential future strategic interest to Pfizer. Caribou will use the proceeds of this investment to advance CB-011, an immune-cloaked allogeneic CAR-T cell therapy in Phase 1 clinical trial in patients with relapsed or refractory multiple myeloma (r/r MM). It is developed based on the CRISPR-Cas12a chRDNA technology platform.
• Poseida Therapeutics announced that the US Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for P-CD19CD20-ALLO1. It is the company's first allogeneic dual CAR-T cell product candidate, which targets both CD19 and CD20 antigens for the treatment of relapsed or refractory B-cell malignancies, and it is developed using the proprietary gene editing platforms, piggyBac and Cas-CLOVER.
• The market value of CRISPR in terms of revenue was estimated to be worth $3.4 billion in 2023 and is poised to reach $7.1 billion by 2028, growing at a CAGR of 15.6% from 2023 to 2028. MarketsandMarkets provided the new report.

Reviews

• Enrichment strategies to enhance genome editing. This review seeks to elucidate the different enrichment strategies, their many applications in non-clinical and clinical settings, and the need for novel strategies further to improve genome research and gene and cell therapy studies.
• Bacteriophage genome engineering for phage therapy to combat bacterial antimicrobial resistance as an alternative to antibiotics. This review focuses on how CRISPR-Cas9 may be used to designate phage therapy as a solid alternative to antibiotics for combatting bacterial antimicrobial resistance (AMR). Gene editing can help overcome limitations such as phage narrow host range, phage resistance or any potential eukaryotic immune response for phage-based enzymes/proteins therapy.
• Decoding the microbiome: advances in genetic manipulation for gut bacteria. This review looks at the current advances and challenges in developing CRISPR-Cas and transposase-based systems in either model or non-model gut bacteria.
• CRISPR-Cas systems in oral bacteria and their role in periodontal disease pathogenesis and periodontal therapy: a review. This review discusses the types of CRISPR genes in oral microbiota, their mechanisms, and how they can manage periodontal disease pathogenicity and periodontal therapy.

Podcast

• In the latest episode of Microbe Talk, David Walker-Sünderhauf from the University of Exeter chats with Clare about his paper "Removal of AMR plasmids using a mobile, broad-host-range CRISPR-Cas9 delivery tool", published in Microbiology. You can read the paper here.

Huh, heh, wow

• Sequencing data from 82 Swedish infants' gut microbiomes have identified 1882 candidate CRISPRs over time in the first year of life. The Researchers from the UK and elsewhere found large-scale dynamic turnover of CRISPRs, including changes in the relative abundance of the bacteria containing CRISPR and acquisition, loss and mutation of spacers within the same CRISPR array. The results underpin CRISPR dynamics and their potential role in the early life interaction between bacteria and phages.

News from CRISPR Medicine News

• On Wednesday, we reported that Intellia Therapeutics recently shared new positive clinical data from the ongoing Phase 1 trial of NTLA-2002 in hereditary angioedema (HAE). NTLA-2002 is an investigational in vivo CRISPR therapy designed to permanently inhibit a major driver of the severe inflammatory attacks seen in HAE.