Clinically relevant gene editing in hematopoietic stem cells for the treatment of pyruvate kinase deficiency.

Pyruvate kinase deficiency (PKD), an autosomal-recessive disorder, is the main cause of chronic non-spherocytic hemolytic anemia. PKD is caused by mutations in the pyruvate kinase, liver and red blood cell (P KLR) gene, which encodes for the erythroid pyruvate kinase protein (RPK). RPK is implicated in the last step of anaerobic glycolysis in red blood cells (RBCs), responsible for the maintenance of normal erythrocyte ATP levels. The only curative treatment for PKD is allogeneic hematopoietic stem and progenitor cell (HSPC) transplant, associated with a significant morbidity and mortality, especially relevant in PKD patients. Here, we address the correction of PKD through precise gene editing at the PKLR endogenous locus to keep the tight regulation of RPK enzyme during erythropoiesis. We combined CRISPR-Cas9 system and donor recombinant adeno-associated vector (rAAV) delivery to build an efficient, safe, and clinically applicable system to knock in therapeutic sequences at the translation start site of the RPK isoform in human hematopoietic progenitors. Edited human hematopoietic progenitors efficiently reconstituted human hematopoiesis in primary and secondary immunodeficient mice. Erythroid cells derived from edited PKD-HSPCs recovered normal ATP levels, demonstrating the restoration of RPK function in PKD erythropoiesis after gene editing. Our gene-editing strategy may represent a lifelong therapy to correct RPK functionality in RBCs for PKD patients.

AsCas12a ultra nuclease facilitates the rapid generation of therapeutic cell medicines.

Though AsCas12a fills a crucial gap in the current genome editing toolbox, it exhibits relatively poor editing efficiency, restricting its overall utility. Here we isolate an engineered variant, "AsCas12a Ultra", that increased editing efficiency to nearly 100% at all sites examined in HSPCs, iPSCs, T cells, and NK cells. We show that AsCas12a Ultra maintains high on-target specificity thereby mitigating the risk for off-target editing and making it ideal for complex therapeutic genome editing applications. We achieved simultaneous targeting of three clinically relevant genes in T cells at >90% efficiency and demonstrated transgene knock-in efficiencies of up to 60%. We demonstrate site-specific knock-in of a CAR in NK cells, which afforded enhanced anti-tumor NK cell recognition, potentially enabling the next generation of allogeneic cell-based therapies in oncology. AsCas12a Ultra is an advanced CRISPR nuclease with significant advantages in basic research and in the production of gene edited cell medicines.

Targeting a cytokine checkpoint enhances the fitness of armored cord blood CAR-NK cells.

Immune checkpoint therapy has resulted in remarkable improvements in the outcome for certain cancers. To broaden the clinical impact of checkpoint targeting, we devised a strategy that couples targeting of the cytokine-inducible Src homology 2-containing (CIS) protein, a key negative regulator of interleukin 15 (IL-15) signaling, with fourth-generation "armored" chimeric antigen receptor (CAR) engineering of cord blood-derived natural killer (NK) cells. This combined strategy boosted NK cell effector function through enhancing the Akt/mTORC1 axis and c-MYC signaling, resulting in increased aerobic glycolysis. When tested in a lymphoma mouse model, this combined approach improved NK cell antitumor activity more than either alteration alone, eradicating lymphoma xenografts without signs of any measurable toxicity. We conclude that targeting a cytokine checkpoint further enhances the antitumor activity of IL-15-secreting armored CAR-NK cells by promoting their metabolic fitness and antitumor activity. This combined approach represents a promising milestone in the development of the next generation of NK cells for cancer immunotherapy.

CRISPR-Cas9 genome editing using targeted lipid nanoparticles for cancer therapy.

Harnessing CRISPR-Cas9 technology for cancer therapeutics has been hampered by low editing efficiency in tumors and potential toxicity of existing delivery systems. Here, we describe a safe and efficient lipid nanoparticle (LNP) for the delivery of Cas9 mRNA and sgRNAs that use a novel amino-ionizable lipid. A single intracerebral injection of CRISPR-LNPs against PLK1 (sgPLK1-cLNPs) into aggressive orthotopic glioblastoma enabled up to ~70% gene editing in vivo, which caused tumor cell apoptosis, inhibited tumor growth by 50%, and improved survival by 30%. To reach disseminated tumors, cLNPs were also engineered for antibody-targeted delivery. Intraperitoneal injections of EGFR-targeted sgPLK1-cLNPs caused their selective uptake into disseminated ovarian tumors, enabled up to ~80% gene editing in vivo, inhibited tumor growth, and increased survival by 80%. The ability to disrupt gene expression in vivo in tumors opens new avenues for cancer treatment and research and potential applications for targeted gene editing of noncancerous tissues.

Large-scale GMP-compliant CRISPR-Cas9-mediated deletion of the glucocorticoid receptor in multivirus-specific T cells.

Virus-specific T cells have proven highly effective for the treatment of severe and drug-refractory infections after hematopoietic stem cell transplant (HSCT). However, the efficacy of these cells is hindered by the use of glucocorticoids, often given to patients for the management of complications such as graft-versus-host disease. To address this limitation, we have developed a novel strategy for the rapid generation of good manufacturing practice (GMP)-grade glucocorticoid-resistant multivirus-specific T cells (VSTs) using clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) gene-editing technology. We have shown that deleting the nuclear receptor subfamily 3 group C member 1 (NR3C1; the gene encoding for the glucocorticoid receptor) renders VSTs resistant to the lymphocytotoxic effect of glucocorticoids. NR3C1-knockout (KO) VSTs kill their targets and proliferate successfully in the presence of high doses of dexamethasone both in vitro and in vivo. Moreover, we developed a protocol for the rapid generation of GMP-grade NR3C1 KO VSTs with high on-target activity and minimal off-target editing. These genetically engineered VSTs promise to be a novel approach for the treatment of patients with life-threatening viral infections post-HSCT on glucocorticoid therapy.