CMN Weekly (27 March 2026) - Your Weekly CRISPR Medicine News

Top picks

• TIGER (Template-Independent Genome Editing for Restoration) is a CRISPR-Cas9 platform that corrects frameshift mutations without a repair template, guided by a gRNA scoring system built on nucleotide-level predictors of editing outcomes. Around 75% of deletion and 50% of insertion mutations yielded sufficient in-frame products for phenotypic restoration. In a mouse deafness model, dual-AAV delivery of SpCas9 and an optimal gRNA restored hearing to wild-type levels.
• Beam Therapeutics reports CRISPR-Cas-derived base editing with BEAM-302 corrects the SERPINA1 PiZ mutation in vivo, restoring functional AAT production. In Phase 1/2 data (n=29), a single 60 mg dose produced durable AAT increases (~16 µM), ~84% reduction in toxic Z-AAT, and ~94% corrected M-AAT, with a favourable safety profile, supporting advancement to pivotal trials and potential accelerated approval.

Research

• A CRISPR-Cas9 strategy targeting the Let-7c microRNA binding site in the UTRN gene upregulates utrophin as a mutation-independent approach to Duchenne muscular dystrophy. Cas9-generated indels in DMD myoblasts effectively relieved repression, with functional improvements confirmed in a three-dimensional tissue-engineered muscle model. AAV-delivered editing in mdx mice produced utrophin upregulation alongside amelioration of muscle histopathology and function.
• A CRISPR-Cas9/AAV6-HDR platform has been used to insert Fancc cDNA into its endogenous locus in haematopoietic stem/progenitor cells from Fancc-deficient mice. Corrected cells showed restored expression, rescued colony-forming capacity, and improved viability. Transplantation into Fancc-/- mice conferred durable resistance to mitomycin C-induced bone marrow failure, establishing homology-directed repair as a viable therapeutic strategy for Fanconi anaemia group C.
• A systematic evaluation of SaCas9-based approaches for HIV-1 proviral excision reveals that kinetic synergy between paired gRNAs is as critical as sequence compatibility, with the dual-guide Gag3 + Pol5 combination achieving 97% excision efficiency. Mismatched kinetic pairings fail to induce excision because the first cut is repaired before the second is realised, offering a mechanistic framework for optimising CRISPR-Cas strategies targeting the persistent HIV reservoir.
• Cryo-EM structures of an engineered IscB capture its transition from autoinhibited resting state to activation, revealing RNA lids that sequentially block the HNH and RuvC active sites. Guide–target pairing displaces the guide RNA in a stepwise "car pedal" motion, triggering a ~90° HNH rotation at 11-nt pairing. Engineering the hinge regions mediating this rotation improved editing efficiency in cells, flagging them as targets for compact editor development.
• A hybrid CRISPR design pipeline improves the predictability of genome editing outcomes in mouse embryos. By favouring microhomology-mediated end joining (MMEJ) and validating guides in stem cells, the study reduces mosaicism and yields uniform genotypes in founder animals.
• Extending the sgRNA spacer from 20 to 21–22 nucleotides restores the reduced cleavage activity of SuperFi-Cas9 while preserving its high-fidelity. Cryo-EM structures reveal that the extended duplex strengthens electrostatic interactions with residues K929, K948, and R951 in the PAM-distal RuvC loop. The findings establish guide RNA architecture as a tunable layer for improving high-fidelity CRISPR-Cas9 performance without sacrificing specificity.
• CRISPRi depletion of the essential nucleoid-associated protein MtHU in Mycobacterium tuberculosis caused broad transcriptional derepression, with more than 800 genes affected. ChIP-seq and RNAP occupancy data indicate that MtHU binds widely, including within coding regions, where it impedes RNA polymerase elongation and acts mainly as a transcriptional repressor. Reducing MtHU also impaired intracellular survival and antibiotic tolerance, highlighting it as a potential therapeutic target.
• CRISPR-Cas9-mediated knock-in of the human erythropoietin (hEPO) gene into the endogenous β-casein locus in HC11 mammary epithelial cells yielded hormone-responsive transgene expression. Lactogenic stimulation drove an approximately 20-fold increase in hEPO protein levels, with purified recombinant protein showing measurable biological activity. The approach demonstrates the β-casein locus as a platform for controlled, inducible expression of therapeutic proteins in mammary epithelial cells.
• Negative supercoiling drives structural DNA defects that are resolved upon CRISPR-Cas9 binding, promoting off-target activity. Cryo-EM structures of Cas9 bound to supercoiled DNA reveal a more catalytically competent HNH domain conformation and topology-dependent structural plasticity in the PAM-distal region. The findings provide a molecular basis for supercoiling-induced off-target activity and a framework for designing high-fidelity CRISPR effectors that account for topological context.
• A foundation model fine-tuned via Low-Rank Adaptation performs per-nucleotide classification of DNA into repeat, spacer, and non-array regions, enabling CRISPR array detection directly from raw sequences. A long-context variant (up to 8,192 nt) achieves 98.16% accuracy and identifies degenerate repeats missed by similarity-based tools; a short-context variant optimised for Illumina reads enables assembly-free metagenomic analysis. The approach offers a robust complement to existing CRISPR array detection methods for fragmented and metagenomic datasets.

Screening

• CRISPR tiling deletion screening in iPSC-derived excitatory neurons identified 39 functional enhancers across four dosage-sensitive neuropsychiatric disease risk genes — APP, FMR1, MECP2, and SIN3A. Allelic enhancer deletions at SIN3A were compensated by increased transcriptional activity from the intact allele, a mechanism maintained through differentiation and mediated by dosage sensing at the promoter. The findings reveal a regulatory compensation mechanism that ensures precise transcriptional output for dosage-sensitive genes.
• Two updated genome-wide CRISPR knockout libraries – Jacquere (human) and Julianna (mouse) – are presented, designed to balance on-target efficacy and off-target avoidance within a unified selection framework. The strategy omits guides only where off-target activity genuinely justifies exclusion, preserving maximally active guides. Both libraries are optimised for compact, high-dimensional screen readouts such as single-cell RNA sequencing and high-content imaging, and are made publicly available.
• CRISPR activation screens in NK-92 cells identified metabolite-sensing receptors — including GPR183, GPR84, GPR34, and GPR18 — as top enhancers of infiltration into breast and ovarian cancers. Expressing GPR183 in NK, CAR-NK, and CAR-T cells increased tumour infiltration and control in vitro and in vivo. The findings establish metabolite-sensing receptor expression as a strategy for biochemically guided, spatially targeted cell therapies against solid tumours.

Detection

• Integrating a bipartite split-crRNA into Cas12a (SCas12a) separates target recognition from PAM dependency, eliminating cis-cleavage while preserving robust trans-cleavage for one-pot CRISPR diagnostics. The system achieves attomolar sensitivity within 30 minutes, with single-base resolution and 100–1,000-fold improved sensitivity over conventional approaches. SCas12a successfully detected HPV16, SARS-CoV-2, and TP53 SNPs in clinical samples, demonstrating strong potential for point-of-care diagnostics.

Reviews

• CRISPR/Cas9 engineering of CAR-T cells: can non-viral nanoparticles unlock safer and scalable genome editing? This review examines how CRISPR-Cas genome engineering can reprogram CAR-T cells to overcome current limitations, comparing viral and non-viral delivery platforms whilst distinguishing established ex vivo editing from emerging in vivo T-cell programming approaches.

News from CRISPR Medicine News

• On Wednesday, we published an interview with Benjamin Oakes, CEO of Scribe Therapeutics, who told us that the company is preparing to take its first cardiometabolic programme into the clinic in mid-2026, positioning STX-1150 as a potentially durable alternative to today’s chronic lipid-lowering therapies. Scribe’s lead asset targets the well-validated PCSK9 pathway, but does so through epigenetic silencing rather than permanent genome editing.