CMN Weekly (20 March 2026) - Your Weekly CRISPR Medicine News

Top picks

• A two-vector system combining CRISPR-Cas9 ribonucleoproteins, delivered via enveloped delivery vehicles, with AAV-carried donor templates achieves in vivo site-specific integration of large CAR transgenes into a T cell-specific locus, generating therapeutic levels of CAR T cells in humanised mouse models of B cell aplasia and haematological and solid malignancies. By enabling stable, cell-specific transgene expression without ex vivo manufacturing, the approach offers a more accessible and precise route to T cell therapies than current random-integration or transient-expression methods.
• Helper-dependent adenoviral vectors delivering all-in-one base editors (HDAd-BEs) were used to achieve in vivo precision editing of the CCR5 gene in haematopoietic stem cells, yielding ~50% base editing in bone marrow mononuclear cells in a humanised mouse model and ~12-fold lower HIV plasma titres after challenge. Efficient CCR5 knockout with no significant off-target effects was also demonstrated in human CD34+ cells, supporting this approach as a durable and potentially affordable route to a functional HIV cure.

Research

• Extending the spacer region to 21–22 nucleotides restores the impaired cleavage activity of SuperFi-Cas9 – a high-fidelity variant carrying seven RuvC domain mutations – by compensating for repulsive electrostatic forces that destabilise the nuclease–sgRNA–DNA complex, as revealed by cryo-electron microscopy and mutational analyses. A deep learning model, AIdit-SuperFi, was developed to predict optimal sgRNA length for high-fidelity editing, offering a practical strategy to balance specificity and efficiency in clinical CRISPR-Cas9 applications.
• A self-inactivating CRISPR-Cas9 system using a Staphylococcus aureus Cas9 (SaCas9) guide RNA targeting mutant HTT achieved elimination of 60–90% of mutant Huntingtin protein and 90% of mHTT aggregation in BAC226Q mouse brains, with the self-inactivating design abolishing SaCas9 after transient expression to minimise off-target effects. Long-term rescue of neuropathology, motor deficits, and lifespan was observed whether editing was applied before or after symptom onset.
• A newly developed pyrethroid-resistant Aedes aegypti strain carrying a Cas9 transgene enables precise functional testing of genes linked to insecticide resistance. The work identifies detoxification pathways and regulatory mechanisms that could guide improved strategies for managing resistance in mosquito control programmes.
• Comprehensive reversion analysis of the 14 mutations installed in the TadA deaminase during directed evolution of ABE7.10 reveals that up to five can be reverted to wild type, yielding minimally evolved ABEs (ME-ABEs) with narrow editing windows, enhanced on-target activity matching ABE8e and ABE8.20, and low guide-RNA-dependent and -independent off-target activity. ME-ABEs successfully targeted six clinically relevant sites previously refractory to editing by ABE7.10, ABE8e, or ABE8.20, offering a more precise and efficient adenine base editing platform.
• Using a luciferase reporter mouse model, this study examined the effect of varying guide RNA dosage on in vivo adenine base editing efficiency when delivered via lipid nanoparticles co-encapsulating ABE8e mRNA. Increasing guide RNA dose to 4 mg/kg enhanced on-target editing up to 3.3-fold across multiple tissues, reaching 63% in the liver, but also elevated bystander editing in a dose-dependent manner, underscoring the need for careful dosage optimisation in therapeutic base editing applications.
• Eight novel Cas12j orthologues identified from viral metagenomes were engineered into T5 exonuclease-Cas12j fusions, substantially enhancing genome-editing activity across multiple mammalian cell types to levels comparable to established compact CRISPR-Cas editors, addressing the delivery constraints imposed by the large size of conventional Cas nucleases. Catalytically inactive Cas12j variants were further coupled with adenine deaminase to enable efficient A-to-G base conversion, establishing Cas12j as a modular, delivery-compatible platform with expanding therapeutic potential.
• A comprehensive workflow for ABE-mediated gene knockout is presented as a user-friendly alternative to conventional Cas9 nuclease approaches, centred on SpliceR – a web-based application for optimised guide RNA design – and validated across 14 immunologically relevant targets using NGG and NG PAM-compatible ABE8e variants in primary immune cells. The accompanying MultiEditRbatch tool extends the existing MultiEditR platform with batch-mode Sanger sequencing analysis, together lowering the practical barriers to adenine base editing as a knockout strategy.
• Analysis of endogenous CRISPR-Cas9 editing data spanning four human cell types, two tomato cell types, giant river prawn, and black soldier fly reveals hundreds of novel features influencing gRNA activity, with dominant factors – including gRNA competition at target sites and local geometric properties – varying markedly across systems and arguing against a universal efficiency model. Codon usage bias emerged as an informative proxy for chromatin accessibility, while repair outcome trends showed greater conservation across contexts, providing a foundation for more generalisable CRISPR guide design tools.

Clinical and preclinical

• YolTech reports that the FDA has cleared YOLT-202, an in vivo adenine base-editing therapy, for a Phase 2/3 trial in adults with alpha-1 antitrypsin deficiency (AAT). In an ongoing first-in-human study, two dosed patients showed rapid, dose-dependent rises in AAT, exceeding the 11 μM protective threshold; the 45 mg cohort reached normal-range levels with more than 95% corrected, functional M-AAT.

Industry

• Specific Biologics will apply CRISPR-Cas–adjacent Dualase editors within an ML-driven platform to predict highly specific genome edits, supported by a CAD$1.8 million grant. The system integrates genomic, structural and experimental data to optimise editor design. Dualase’s two-site mechanism collapses pathogenic repeat expansions, with lead work targeting C9ORF72 ALS. The approach aims to accelerate candidate discovery across repeat-expansion disorders, including Huntington’s disease.

Q4 and full-year 2025 financial results

• Precision BioSciences reports full-year net loss of $47 million and a cash deposit of $137 million. Q4 net loss was $19 million.
• Cellectis reports full-year net loss of $68 million and a cash deposit of $211 million. Q4 net loss was $26 million.
• Allogene Therapeutics reports full-year net loss of $191 million and a cash deposit of $258 million. Q4 net loss was $39 million.
• Korro reports full-year net loss of $117 million and a cash deposit of $85 million.

Screening

• Genome-wide CRISPR loss-of-function screening in EXO1-deficient cells identified differential regulators of cisplatin sensitivity, revealing that EXO1 is critical for repair of cisplatin-induced DNA damage – a role distinct from its function in wildtype cells. Synthetic lethality screens further uncovered a genetic interaction between EXO1 and the histone chaperone CAF-1, with both independently recruited to R-loops via separate, synergistic suppression pathways whose concomitant loss drives R-loop accumulation and genomic instability.
• A library of 444 lung-targeting lipids (LuT lipids) was synthesised and screened for LNP-mediated delivery of mRNA and CRISPR-Cas9 to the lungs, identifying a lead 'tripod-like' structure – quaternary amine head, three long alkyl chains, and a short handle – that achieved a 9.2-fold improvement in CRISPR-Cas9 gene-editing efficiency and over 90% lung selectivity compared to benchmark DOTAP SORT LNPs. Structure–activity analysis further revealed that enhanced endosomal escape and plasma protein adsorption underpin the superior targeting performance of these novel lipids.
• A pooled single-cell CRISPR screen targeting pluripotency-specific essential transcription factors in human pluripotent stem cells (hPSCs) reveals a highly interconnected gene regulatory network governing self-renewal, differentiation, survival, and transposable element expression. The screen identifies distinct transcription factors acting as lineage-specific gatekeepers that block exit from pluripotency and others that inhibit it, while. Perturbation in naïve hPSCs uncovers both conserved and state-specific regulatory roles – collectively defining an extended pluripotency network with implications for disease modelling and regenerative therapies.
• Tensor decomposition (TD) is presented as a computational approach for integrating multiple sgRNA profiles simultaneously in genome-wide CRISPR-Cas9 knockout screens, achieving gene essentiality discrimination comparable to the leading JACKS method while remaining operable without control samples – a requirement that renders JACKS unusable in certain experimental settings. The study also questions the routine practice of log-transforming raw count data, as TD achieves comparable performance on the largest tested dataset without this step.
• A focused CRISPR-Cas9 screen to identify regulators of ferroptosis suppressor protein 1 (FSP1) uncovered riboflavin (vitamin B2) as a modulator of ferroptosis sensitivity, with riboflavin shown to support FSP1 stability and the recycling of lipid-soluble antioxidants to mitigate phospholipid peroxidation. The riboflavin antimetabolite roseoflavin markedly impairs FSP1 function and sensitises cancer cells to ferroptosis, pointing to riboflavin metabolism as a tractable target for modulating antioxidant capacity in therapeutic contexts.

Detection

• A novel detection platform (MCDA-CRISPR) combining multiple cross-displacement amplification with CRISPR-Cas12a biosensing enables isothermal Brucella detection at 64°C within 60 minutes, achieving a sensitivity of 1 fg/μL – 100-fold greater than conventional PCR – with 100% specificity and no cross-reactivity to non-Brucella pathogens. Results are directly visualised under UV light without specialist equipment, and successful screening of blood donors in Xinjiang underscores the platform's potential for resource-limited and field-based brucellosis surveillance.
• An RPA-Cas12a assay for quantitative CMV DNA detection was developed and calibrated against the WHO international standard, achieving sensitivity and specificity exceeding 80% more quickly and economically than PCR – though performance with Sierra Leonean infant saliva requires further optimisation. The assay highlights the potential of CRISPR-Cas12a-based diagnostics as a scalable, low-resource tool for congenital CMV screening, with the authors proposing synergistic use alongside PCR to expand universal screening efforts.
• A smartphone-integrated CRISPR-LFA platform for point-of-care HPV DNA detection in plasma was enhanced with a machine learning framework using radiomics-inspired strip feature analysis, achieving 96.7% sensitivity and 100% specificity across 210 samples – outperforming visual band interpretation, particularly for faint results. Performance remained consistent across smartphone models, lighting conditions, and operators, supporting the platform's potential to expand accessible, reliable HPV screening in resource-limited settings.

Perspectives and podcasts

• A Perspective in CRISPR Medicine News entitled "Delivery of Gene Editing Components to Skeletal Muscle Using Lipid Nanoparticles: A Game Changer for Muscle Diseases" by Cecilia Jimenez Mallebrera discusses how CRISPR-Cas delivery via lipid nanoparticles enables transient editing in skeletal muscle, including dystrophin restoration. The author argues that LNPs enable durable editing via satellite cells but are limited by liver tropism, requiring improved design and targeting for effective systemic muscle delivery.
• A communication piece in Gene Therapy reports the development of a standardised patient lexicon for CRISPR-Cas9 gene editing in haemophilia, produced through qualitative research, language audits, and workshops involving patients, caregivers, clinicians, and scientific organisations. Intended as a template for other therapeutic areas, the lexicon aims to support consistent communication across clinical sites and geographies, facilitating informed consent and shared decision-making as gene editing therapies advance through development.
• A Perspective in The Linacre Quarterly examines CRISPR-Cas9 through Christian bioethics, framing genome editing within the imago Dei and Thomistic-Augustinian thought. It critiques utilitarian approaches, interrogates therapy–enhancement boundaries and embryo ethics, and proposes a virtue-based framework to guide responsible clinical use while preserving human dignity and moral limits.
• A podcast entitled "Editing Away Autoimmunity at the HLA Source" by The Bio Report takes a closer look at RheumaGen's efforts to develop CRISPR-Cas-based therapies to selectively disrupt pathogenic HLA alleles driving autoimmunity, aiming to preserve overall immune function.

Reviews

• Decoding disease-relevant variants with base and prime editors at scale. This review outlines how CRISPR-Cas base and prime editing technologies are advancing precision functional genomics by enabling systematic interpretation of genetic variation and linking genotype to phenotype, with emphasis on their potential and limitations in research and clinical translation.
• Insights from Stem Cell and CRISPR-Based Therapies for Diabetes Mellitus: A Systematic Review. This review surveys CRISPR-Cas9-based genome editing strategies for diabetes mellitus, covering key pathogenic gene targets and early evidence of improved glycaemic control, whilst acknowledging outstanding technical, safety, and ethical limitations.

News from CRISPR Medicine News

• On Wednesday, we published an original Perspective by Cecilia Jimenez-Mallebrera that explores the rapidly evolving role of LNPs in delivering gene editing tools to skeletal muscles. This exclusive contribution – written specifically for CMN and not published elsewhere – offers a clear-eyed look at current challenges, emerging data, and future strategies in the field.