SAN FRANCISCO, April 22, 2026 - Thryv Therapeutics Inc., a pioneering clinical-stage biotechnology firm, has marked significant progress in its quest to develop novel therapies for inherited cardiac arrhythmias. The company announced that it has commenced patient dosing in its Wave II clinical study for THRV-1268, aimed at treating genetically confirmed Long QT Syndrome (LQTS) Type 2. In a noteworthy development, the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation for THRV-1268, facilitating expedited development for both Long QT Syndrome Type 2 and Type 3.

1. Commencement of Patient Dosing in Wave II Clinical Study

Thryv Therapeutics is currently enrolling patients at leading inherited arrhythmia centers throughout the United States for its multicenter Phase 2/3 Wave II trial (NCT07277582). This study will assess the safety and efficacy of two dose levels of THRV-1268 over a 12-week period. The primary endpoint focuses on measuring changes in QTcF over six hours, as well as evaluating cardiac rhythm stability, safety, and tolerability.

Dr. Vasanth Vedantham, MD, PhD, a Professor of Medicine and Cardiac Electrophysiologist at UCSF Health, has initiated the dosing for the first of fourteen patients in Part A of the Wave II study. Dr. Vedantham expressed optimism regarding the potential of THRV-1268, stating, "The emerging clinical evidence for SGK1's role in cardiac electrophysiology gives me hope that we may finally have a new approach to Long QT Syndrome that addresses the underlying QT interval prolongation."

Initially, participants will receive THRV-1268 in an oral suspension format, which is designed to expedite data collection for pediatric formulations. After the initial 12-week dosing period, patients may transition to an adult tablet for continued therapy lasting up to one year.

2. FDA Fast Track Designation: A Significant Milestone

The Fast Track Designation awarded by the FDA is crucial as it aims to expedite the development and review processes for investigational therapies addressing serious conditions with unmet medical needs. This designation allows for more frequent interactions with the FDA and, if applicable criteria are met, the potential eligibility for Rolling Review, Priority Review, and Accelerated Approval.

Dr. Amy Sehnert, MD, FACC, Chief Medical Officer of Thryv Therapeutics, commented on the significance of this designation: "Fast Track Designation represents a meaningful regulatory milestone that reflects the serious and underserved nature of genetically defined Long QT Syndrome. This recognition by the FDA reinforces our confidence in THRV-1268 and its potential to become the first disease-modifying therapy to specifically target the underlying disease biology of Long QT Syndrome."

3. About Thryv Therapeutics

Thryv Therapeutics is at the forefront of precision medicine, focusing on the treatment of genetic arrhythmia syndromes and cardiometabolic diseases through innovative SGK1 inhibitors. The company remains committed to advancing its clinical programs and improving the lives of patients affected by these serious conditions.

As Thryv Therapeutics moves forward with the Wave II study and benefits from the Fast Track Designation, the hopes for a breakthrough treatment for Long QT Syndrome grow stronger, promising potential relief for patients and their families who face the challenges of this life-threatening condition.

For further updates, stakeholders and interested parties can visit Clinical Trials or Wave Studies for more information on the ongoing clinical studies.

Original press release