“In Vivo CRISPR Base Editing of PCSK9 Durably Lowers Cholesterol in Primates”, Kiran Musunuru, Alexandra C. Chadwick, Taiji Mizoguchi, Sara P. Garcia, Jamie E. DeNizio, Caroline W. Reiss, Kui Wang, Sowmya Iyer, Chaitali Dutta, Victoria Clendaniel, Michael Amaonye, Aaron Beach, Kathleen Berth, Souvik Biswas, Maurine C. Braun, Huei-Mei Chen, Thomas V. Colace, John D. Ganey, Soumyashree A. Gangopadhyay, Ryan Garrity, Lisa N. Kasiewicz, Jennifer Lavoie, James A. Madsen, Yuri Matsumoto, Anne Marie Mazzola, Yusuf S. Nasrullah, Joseph Nneji, Huilan Ren, Athul Sanjeev, Madeleine Shay, Mary R. Stahley, Steven H. Y. Fan, Ying K. Tam, Nicole M. Gaudelli, Giuseppe Ciaramella, Leslie E. Stolz, Padma Malyala, Christopher J. Cheng, Kallanthottathil G. Rajeev, Ellen Rohde, Andrew M. Bellinger, Sekar Kathiresan2021-05-19 (; similar)⁠:

Gene-editing technologies, which include the CRISPR-Cas nucleases and CRISPR base editors, have the potential to permanently modify disease-causing genes in patients. The demonstration of durable editing in target organs of nonhuman primates is a key step before in vivo administration of gene editors to patients in clinical trials.

Here we demonstrate that CRISPR base editors that are delivered in vivo using lipid nanoparticles can efficiently and precisely modify disease-related genes in living cynomolgus monkeys (Macaca fascicularis).

We observed a near-complete knockdown of PCSK9 in the liver after a single infusion of lipid nanoparticles, with concomitant reductions in blood levels of PCSK9 and low-density lipoprotein cholesterol of ~90% and about 60%, respectively; all of these changes remained stable for at least 8 months after a single-dose treatment.

In addition to supporting a ‘once-and-done’ approach to the reduction of low-density lipoprotein cholesterol and the treatment of atherosclerotic cardiovascular disease (the leading cause of death worldwide), our results provide a proof-of-concept for how CRISPR base editors can be productively applied to make precise single-nucleotide changes in therapeutic target genes in the liver, and potentially in other organs.

Figure 2: Short-term effects of adenine base editing of PCSK9 in cynomolgus monkeys. a, Editing of the PCSK9 exon 1 splice-donor adenine base in the livers of cynomolgus monkeys (labeled 1–5) that received an intravenous infusion of a dose of 1.0 mg kg−1 LNP formulation with ABE8.8 mRNA and PCSK9-1 gRNA, with necropsy at 2 weeks (3 monkeys) or 24 h (2 monkeys) after treatment. Control, monkey that received phosphate-buffered saline (PBS) and was necropsied at 2 weeks. For each monkey, editing was assessed in samples collected from sites distributed throughout the liver. n = 8 samples; bar indicates the mean editing in the monkey. b, c, Per cent change in the levels of PCSK9 (b) or LDL cholesterol (c) in blood in the 3 monkeys from a that underwent necropsy at 2 weeks after treatment, comparing the level at 2 weeks with the baseline level before treatment. n = 1 blood sample per monkey. d, Tissue distribution of editing of the PCSK9 exon 1 splice-donor adenine base in the 3 monkeys from a that underwent necropsy at 2 weeks after LNP treatment, and in the control monkey. n = 1 sample per monkey for each indicated organ, except for the liver; the liver data represent the mean shown in a calculated from 8 liver samples each. e–g, Dose-response study, with liver PCSK9 editing (e) and reduction of the levels of PCSK9 (f) or LDL cholesterol (g) in blood upon necropsy at 2 weeks after treatment with a dose of 0.5 mg kg−1, 1.0 mg kg−1 or 1.5 mg kg−1 of the ABE8.8 and PCSK9-1 LNPs. n = 3 monkeys per dose group; data obtained and shown in same manner as in a–c.
Figure 3: Long-term effects of adenine base editing of PCSK9 in cynomolgus monkeys. a, Editing of the PCSK9 exon 1 splice-donor adenine base in the livers of 4 cynomolgus monkeys that received an intravenous infusion of a dose of 3.0 mg kg−1 LNP formulation with ABE8.8 mRNA and PCSK9-1 gRNA, and 2 control monkeys that received PBS. For each monkey, editing was assessed in a liver biopsy sample at 2 weeks after treatment. n = 1 sample per monkey. b, c, Changes in the levels of PCSK9 (b) and LDL cholesterol (c) in blood of the 6 monkeys from a, comparing levels at various time points up to 238 days after treatment with the baseline level before treatment. Mean ± s.d. for the LNP-treated group (<em>n</em> = 4 monkeys) and mean for the control group (<em>n</em> = 2 monkeys), at each time point. The dotted lines indicate 100% and 10% (b) or 100% and 40% (c) of baseline levels.
Figure 3: Long-term effects of adenine base editing of PCSK9 in cynomolgus monkeys. a, Editing of the PCSK9 exon 1 splice-donor adenine base in the livers of 4 cynomolgus monkeys that received an intravenous infusion of a dose of 3.0 mg kg−1 LNP formulation with ABE8.8 mRNA and PCSK9-1 gRNA, and 2 control monkeys that received PBS. For each monkey, editing was assessed in a liver biopsy sample at 2 weeks after treatment. n = 1 sample per monkey. b, c, Changes in the levels of PCSK9 (b) and LDL cholesterol (c) in blood of the 6 monkeys from a, comparing levels at various time points up to 238 days after treatment with the baseline level before treatment. Mean ± s.d. for the LNP-treated group (n = 4 monkeys) and mean for the control group (n = 2 monkeys), at each time point. The dotted lines indicate 100% and 10% (b) or 100% and 40% (c) of baseline levels.

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In Vivo CRISPR Base Editing of PCSK9 Durably Lowers Cholesterol in Primates