CMN Weekly (4 October 2024) - Your Weekly CRISPR Medicine News

Top picks

• Poseida Therapeutics has announced new interim clinical data from its ongoing Phase 1 trial of P-BCMA-ALLO1 in patients with relapsed/refractory multiple myeloma (RRMM). The Cas-CLOVER gene editing therapy demonstrated a 91% overall response rate (ORR) and compelling safety results in the 23 heavily pretreated patients in Arm C, an optimised lymphodepletion arm.
• French researchers have successfully delivered ribonucleoprotein complexes of Cas9 or adenine-base editors and guide RNA into retinal cells in mice's eyes. Gene editing in retinal pigment epithelium and photoreceptors varied by guide RNA and target site, but high Cas9 concentrations caused outer retinal toxicity, highlighting the need for improved delivery methods for safe therapeutic use in retinal dystrophies.

Research

• A novel method, Extended Prime Editing (exPE), significantly improves genome editing efficiency, especially in poly-T regions. It enhances base conversions and insertions up to 259-fold and enables seamless insertion of gene-sized DNA fragments, potentially correcting nearly 90% of human genetic variants, expanding its use in research and therapy.
• Chinese researchers have used CRISPR-based base editors (BEs) and prime editors (PEs) to modify CD123 epitopes on healthy stem cells, protecting them from CAR-T therapy in acute myeloid leukaemia (AML). While BEs introduced unwanted by-products, PE optimisation improved editing efficiency from 5.9% to 78.9%, preserving normal cell function. Edited cells in humanised mice resisted CAR-T lysis, suggesting a potential strategy for relapsed AML treatment.
• A new class of siloxane-incorporated lipid nanoparticles (SiLNPs) has been engineered to enhance intracellular mRNA delivery for tissue-specific therapeutic applications. The siloxane moiety improves cellular uptake and endosomal escape, enabling organ-specific gene editing, including efficient CRISPR-Cas9-based knockout in liver and lung tissues.
• CRISPR interference studies have identified a transposable element (TE) in Alzheimer's disease that suppresses the anti-inflammatory gene C1QTNF4, worsening neuroinflammation. Researchers found 26,188 TE QTLs in aged AD brains, highlighting TE dysregulation as a factor in AD and a potential marker for risk genes.
• German scientists have presented a dual modification strategy that combines CRISPR-Cas9 and CAR technology to enhance the efficacy of natural killer (NK) cells against acute myeloid leukaemia (AML). Single-cell transcriptomics and epitope analyses confirmed that the engineered cells retained their activation and maturation features, leading to improved anti-leukaemic activity.
• A Dutch study shows that CRISPR-Cas9, combined with the lipopeptide C18:1-LAH5, can effectively correct splicing defects caused by deep-intronic variants in ABCA4, linked to Stargardt disease. Targeting introns 30 and 36, CRISPR editing reduced faulty transcripts by ~50% in patient-derived cells without disrupting ABCA4 expression, demonstrating a promising approach for treating splicing-related defects in Stargardt disease.
• CRISPR base editing using dCas9, instead of nickaseCas9, fused with ABE8e significantly reduced large deletions at homologous regions, preserving editing efficiency. In human stem cells, the dCas9 base editor edited gamma and beta globin genes without generating insertions or deletions, enabling precise multiplexed editing.
• American researchers have shown that multi-target CRISPR gRNA vectors are more effective than single-target ones in reducing Ube3a-ATS expression for Angelman syndrome. AAV integration dominated edits (67-89%), with polyA and reverse promoter elements reducing transcription by up to 50%. This suggests vector elements and target site numbers significantly influence gene editing outcomes.

Industry

• Prime Medicine has announced a strategic research collaboration and license agreement with Bristol Myers Squibb to develop reagents for the next generation of ex vivo T-cell therapies. Under the terms of the agreement, Prime Medicine will design optimised prime editor reagents for a select number of targets. At the same time, Bristol Myers Squibb will be responsible for the development, manufacturing and commercialisation of the next-generation cell therapies, with support from Prime Medicine in gene editing strategy and reagent development.
• Prime Medicine also announced that it is focusing its pipeline on a set of high-value programs, each targeting a disease with well-understood biology and a clearly defined clinical development and regulatory path. Each is expected to provide the foundation for expansion into additional opportunities.
• Precision BioSciences has submitted Clinical Trial Applications (CTA) to initiate a Phase 1 study evaluating PBGENE-HBV. PBGENE-HBV is an in vivo gene editing program designed to potentially cure chronic hepatitis B virus (HBV) by eliminating cccDNA, the key source of replicating HBV, while also inactivating integrated HBV DNA in hepatocytes.
• Editas Medicine has secured $57 million in non-dilutive financing by selling future Cas9 licensing fees to DRI Healthcare Trust. This deal will fund further development of Editas' CRISPR-Cas pipeline, including medicines for sickle cell disease and beta thalassaemia. The agreement includes up to 100% of certain future license payments from Vertex Pharmaceuticals, while Editas retains other milestone-based payments.
• ERS Genomics has granted Université de Montréal a CRISPR-Cas9 license, enabling the launch of two screening platforms at its cancer research institute. This will expand CRISPR access for genome-wide screening and collaborations, aiming to identify new therapeutic targets. Financial details were not disclosed.

CRISPR screens

• A new study using a CRISPR-Cas9 screen has identified key gene knockouts that restore the activation of neural stem cells (NSCs) in ageing mice. The results provide insights into how stem cell function declines with age and identify glucose metabolism as a key factor in this process, as demonstrated by the knockout of the Slc2a4 gene, which encodes the GLUT4 glucose transporter.
• Using whole genome CRISPR-Cas9 knockout screens, researchers have identified eight genes linked to CDK4/6 inhibitor resistance in breast cancer, with SEMA3F being key. SEMA3F knockdown increased cell survival and cyclin kinase activity, driving resistance.

Detection

• A new rapid fluorescence and lateral flow NAT assay utilises a split Cas12a system (SCas12a) consisting of a Cas12a enzyme and a split crRNA. The SCas12a assay enables highly sensitive, amplification-free, and multiplexed detection of miRNAs and long RNAs without complex secondary structures.
• Chinese researchers present CrisprAIE, which improves CRISPR-Cas diagnostics by using aggregation-induced emission fluorescence. This boosts sensitivity for detecting viruses like SARS-CoV-2 without amplification. Combining it with spherical nucleic acids and a portable device enhances sensitivity up to 270-fold, offering a scalable, high-performance diagnostic method.

Reviews

• Modelling and deciphering tumour metabolism in CRISPR screens. This review describes the development of a diploid seedless watermelon inducer by mutating the ClHAP2 gene, which disrupts double fertilisation, offering an alternative to traditional methods of seedless watermelon production.
• CRISPR/Cas9-Mediated Homology-Directed Repair for Precise Gene Editing. This review focuses on CRISPR-Cas9-mediated homology-directed repair (HDR), highlighting strategies to improve its efficiency and its applications in precise genome editing for protein studies, disease modelling, and gene therapies.
• Strategies for improving the genome-editing efficiency of class 2 CRISPR/Cas system. This review explores the characteristics and optimisation strategies of CRISPR-Cas systems, focusing on enhancing editing efficiency and discussing advancements in base editors, prime editors, gene regulation tools, and compact systems.
• Gene therapy for chronic pain management. This review examines various gene therapy strategies, including ASOs, small interfering RNA (siRNAs), optogenetics, chemogenetics, and CRISPR, and their delivery methods targeting primary sensory neurons and non-neuronal cells, including glia and chondrocytes.
• Exploring retinal degenerative diseases through CRISPR-based screening. This review provides a comprehensive overview of CRISPR tools and screening methods, highlighting their potential for advancing retinal degenerative disease research and therapeutic development.

News from CRISPR Medicine News

• On Monday, we interviewed two scientists from Cellectis. They have developed dual CAR-T cells incorporating an IF/THEN logic-gated system that show enhanced anti-tumour cytotoxicity and reduced off-tumour effects in mouse models. The TALEN-edited CAR-T cells provide a promising approach for targeting solid tumours while mitigating safety risks.
• Last Friday, we broadcast a CMN Live interview on LinkedIn with Xavier Duportet, CEO at Eligo Bioscience. In a chat with our editor-in-chief, Karen O'Hanlon Cohrt, he talked about the human microbiome, its role in health and disease, and how gene editing within the microbiome will open a whole new chapter in medicine.