Chemical optimization of siRNA for safe and efficient silencing of placental sFLT1

Sarah M Davis; Vignesh N Hariharan; Agnes Lo; Anton A Turanov; Dimas Echeverria; Jacquelyn Sousa; Nicholas McHugh; Annabelle Biscans; Julia F Alterman; S Ananth Karumanchi; Melissa J Moore; Anastasia Khvorova

doi:10.1016/j.omtn.2022.06.009

Chemical optimization of siRNA for safe and efficient silencing of placental sFLT1

Mol Ther Nucleic Acids. 2022 Jun 22:29:135-149. doi: 10.1016/j.omtn.2022.06.009. eCollection 2022 Sep 13.

Authors

Sarah M Davis¹, Vignesh N Hariharan¹, Agnes Lo^{2

3}, Anton A Turanov¹, Dimas Echeverria¹, Jacquelyn Sousa¹, Nicholas McHugh¹, Annabelle Biscans¹, Julia F Alterman¹, S Ananth Karumanchi^{2

3

4}, Melissa J Moore^{1

5}, Anastasia Khvorova^{1

6}

Affiliations

¹ RNA Therapeutics Institute, University of Massachusetts Medical School, AS4-1049, 368 Plantation Street, Worcester, MA 01605, USA.
² Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, MA, USA.
³ Harvard Medical School, Boston, MA, USA.
⁴ Deparment of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
⁵ Moderna Therapeutics, Cambridge, MA, USA.
⁶ Department of Molecular Medicine, University of Massachusetts Medical School, AS4-1049, 368 Plantation Street, Worcester, MA 01605, USA.

Abstract

Preeclampsia (PE) is a rising, potentially lethal complication of pregnancy. PE is driven primarily by the overexpression of placental soluble fms-like tyrosine kinase 1 (sFLT1), a validated diagnostic and prognostic marker of the disease when normalized to placental growth factor (PlGF) levels. Injecting cholesterol-conjugated, fully modified, small interfering RNAs (siRNAs) targeting sFLT1 mRNA into pregnant mice or baboons reduces placental sFLT1 and ameliorates clinical signs of PE, providing a strong foundation for the development of a PE therapeutic. siRNA delivery, potency, and safety are dictated by conjugate chemistry, siRNA duplex structure, and chemical modification pattern. Here, we systematically evaluate these parameters and demonstrate that increasing 2'-O-methyl modifications and 5' chemical stabilization and using sequence-specific duplex asymmetry and a phosphocholine-docosanoic acid conjugate enhance placental accumulation, silencing efficiency and safety of sFLT1-targeting siRNAs. The optimization strategy here provides a framework for the chemical optimization of siRNAs for PE as well as other targets and clinical indications.

Keywords: angiogenic disorders; extrahepatic delivery; methyl rich siRNA; oligonucleotide drug design; oligonucleotides; pre-clinical development; preeclampsia; siRNA optimization; siRNA therapeutics.

Abstract

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