Identification of enzymatically modified isoquercitrin (EMIQ) as a therapeutic candidate for myotonic dystrophy type 1

Topic:

Pre-Clinical Research

Poster Number: O52

Author(s):

SUBODH MISHRA, PhD, The RNA Institute, University at Albany, Albany, NY USA, Sawyer M. Hicks, PhD, The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York,, Jesus A. Frias, PhD, The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York,, Sweta Vangaveti, PhD, The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York,, Tammy S Reid, MSc, The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York,, Christopher Crumbaugh, PhD, 3Center for Inherited Myology Research, Virginia Commonwealth University, Richmond VA 23298, USA. 4D, Omari McMichael, PhD, 3Center for Inherited Myology Research, Virginia Commonwealth University, Richmond VA 23298, USA. 4D, Marina Provenzano, PhD, 3Center for Inherited Myology Research, Virginia Commonwealth University, Richmond VA 23298, USA. 4D, Melissa A. Hale, PhD, 3Center for Inherited Myology Research, Virginia Commonwealth University, Richmond VA 23298, USA. 4D, Nicholas E. Johnson, MD PhD, 3Center for Inherited Myology Research, Virginia Commonwealth University, Richmond VA 23298, USA. 4D, Masayuki Nakamori, PhD MD, 5Department of Neurology, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan, Kaalak Reddy, PhD, 1The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York, J. Andrew Berglund, PhD, 1The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York, John D. Cleary, PhD, 1The RNA Institute, College of Arts and Sciences, University at Albany, State University of New York

Background and Objective: Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by a CTG repeat expansion in the 3′ UTR of the DMPK gene. This expansion leads to the production of toxic CUG repeat RNA, which sequesters MBNL proteins, resulting in widespread MBNL dependent mis-splicing, a hallmark of DM1 pathogenesis. Currently, no FDA-approved disease-targeting treatments are available for DM1. This study identifies enzymatically modified isoquercitrin (EMIQ), a bioavailable derivative of quercetin, as a therapeutic candidate that selectively reduces toxic RNA production, leading to the rescue of MBNL dependent mis-splicing and improvement of myotonia, a phenotypic hallmark of DM1.

Methods: Previously, our lab developed a HeLa screening cell line that enables ratiometric evaluation of toxic r(CUG)480 RNA levels relative to an r(CUG)0 control1. This HeLa cell line served as a screening platform to identify compounds from the NCI Natural Product Library V that selectively reduce toxic r(CUG)480 RNA levels. Quercetin was further tested in DM1 patient-derived myotubes for its ability to rescue MBNL dependent mis-splicing and reduce DMPK transcript levels. The in vivo efficacy of a bioavailable derivative of quercetin, EMIQ was evaluated in the HSALR DM1 mouse model by assessing expanded CUG RNA levels, mis-splicing rescue, and myotonia following oral EMIQ treatment.

Results and conclusion: Primary and secondary screening in a DM1 HeLa cell line revealed the dietary flavonoid quercetin as a selective modulator of toxic CUG RNA levels without significantly affecting cellular viability. Furthermore, treatment of DM1 patient-derived myotubes with quercetin resulted in a significant reduction in DMPK transcript levels and rescued MBNL dependent mis-spliced events without significant impacts on cell viability. Finally, in DM1 mice, oral treatment with EMIQ, a bioavailable form of quercetin, selectively reduced toxic CUG RNA levels, mitigated DM1-associated mis-splicing, and reduced myotonia. No adverse events were noted in these animals and quercetin was detected in both muscle and brain of treated animals aligning with EMIQ’s well established safety and bioavailability profile This data coupled with its in vivo efficacy, positions EMIQ as a promising candidate for future clinical evaluation as a disease-modifying therapy for DM1.