Using adenine base editors, we aim to treat sickle cell disease by generating single nucleotide polymorphisms in human CD34+ hematopoietic stem and progenitor cells (HSPCs) at specific target sites by mediating A-T to G-C base conversions. While ex vivo gene editing approaches show great therapeutic promise, access is limited due to the requirement of an autologous hematopoietic stem cell (HSC) transplant to deliver the ex vivo edited cells. To further increase the number of patients eligible for base editing therapy, we are developing an alternative approach to directly deliver base editors to HSCs in vivo through non-viral delivery methods. Lipid Nanoparticles (LNPs) are a clinically validated, non-viral approach that enables the delivery of nucleic acid payloads, which may avoid the challenges associated with ex vivo approaches including the transplantation of edited CD34+ HSPCs. Here we describe the development and characterization of LNPs for the delivery of messenger RNA (mRNA) to HSPCs in vivo in both mice and cynomolgus macaques. By screening >1,000 chemically distinct LNPs in vivo utilizing a DNA barcoding technology, we identified several hit LNPs capable of biodistribution to HSPCs. Upon individual validation of these hit LNPs by delivery of Cre recombinase mRNA in a Cre-reporter mouse model (Ai14), which expresses the fluorescent protein tdTomato under a constitutive CAG promoter following Cre-meditate gene editing, we confirmed that several LNPs efficiently delivered Cre recombinase mRNA to mouse Lin-Sca-1+c-Kit+ (LSK) HSPCs. We next confirmed the most potent hit LNP (LNP-HSC1) identified from the in vivo screen to transfect LSK HSPCs in a dose-dependent manner between 0.1 and 1.0 mg/kg Cre recombinase mRNA, transfecting over 40% of LSK HSPCs in Ai14 mice at 1.0mg/kg. In a transfection durability study using Ai14 mice, we observed maintenance of tdTomato+ LSK HSPCs levels in the bone marrow at 10 weeks post-LNP delivery. As LNP-HSC1 had been identified and validated in mice of a C57BL6/j background, we next confirmed its ability to transfect a reporter mRNA into HSPCs in Balb/c mice and in 5 cynomolgus macaques. LNP-HSC1 efficiently transfected LSK HSPCs in Balb/c mice at doses ranging from 0.3 to 1.0 mg/kg. In 5 cynomolgus macaques (n=5 across two experiments), we observed a dose-dependent increase in reporter mRNA delivery with an average of 19% of bone marrow-derived CD34+ HSPCs (n=3) expressing the reporter protein at the highest dose tested. Taken together, these data demonstrate the value of our in vivo high-throughput LNP screening approach to identify novel LNPs capable of delivering to HSPCs, providing a promising delivery platform for an in vivo HSC gene editing approach for the treatment of hemoglobinopathies. Disclosures Sago: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Campbell: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Lutz: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Patwardhan: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Hamilton: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wong: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Lee: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Keating: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Murray: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Singh: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company. Ciaramella: Beam Therapeutics: Current Employment, Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees.
Background Receipt of opioid prescriptions in pediatric and young adult patients may be a risk factor for future opioid misuse. Data from prescription drug monitoring programs provide insight on outpatient opioid use. In our study, we analyzed the opioid dispensing rates for pediatrics and young adults in California. Methods A secondary analysis was performed from 2015-2019 using Controlled Utilization Review and Evaluation System data. This database provides dispensing data of controlled substances in California. Patients younger than 25 years who were prescribed opiates were analyzed by county. We further divided them into two groups (children: ≤14 years; adolescents and young adult: 15-24 years). Descriptive statistics and heat maps were used to illustrate the trends in opioid usage among different age groups. Results The overall percentages for the number of opioids being dispensed to patients aged <25 years have decreased over the past four years. In 2015, 6 out of 58 counties in California were considered “high-rate” with >2.9% of opioids dispensed to patients younger than 25 years old; in 2019, this number reduced to zero. Patients 25 and older received a higher proportion of opioids compared to younger populations; in 2019, 35.91% of opioids were dispensed to patients 45-64, and 8.92% to patients younger than 25. Conclusion Pediatric opioid prescriptions have declined over the recent years. However, a high degree of variability of prescription rates between demographic counties was noted. More studies are warranted in order to understand this discrepancy in opioid prescribing among pediatric and young adult patients.
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