Regulus Therapeutics announced initiation of dosing in its Phase 1b clinical study of RGLS4326 in patients with ADPKD.

The Phase 1b is an adaptive design, open-label, multiple dose study in up to three cohorts of patients with ADPKD and will evaluate administration of RGLS4326 for safety, pharmacokinetics, and changes in levels of polycystin 1 (PC1) and polycystin 2 (PC2). Patients with ADPKD, due to a mutation in the PKD genes, have been reported to have low levels of PC1 and PC2, the proteins encoded by the PKD1 and PKD2 genes, respectively. This study is designed to assess whether different dose levels of RGLS4326 can increase levels of PC1 and PC2 in ADPKD patients. The first cohort is expected to enroll up to nine patients who will receive RGLS4326 every two weeks over a six week period. The Company anticipates availability of results from the first cohort by the end of Q1 2021.

The Company plans to use the data from this first cohort of patients with ADPKD, together with the data from the multiple ascending dose and the single ascending dose studies in healthy volunteers as well as the recently completed nonclinical studies, to obtain feedback from the U.S. Food & Drug Administration (FDA) on the acceptability of the Company's approach to addressing the second set of FDA requirements to support studies of extended duration in patients.

"We are excited to evaluate this potentially disease modifying investigational drug in patients with ADPKD," said Jay Hagan, CEO of Regulus. "This Phase 1b study will provide important data on safety, pharmacokinetics, and biomarkers of ADPKD which we plan to use in our approach to address the remaining partial clinical hold requirements."