Seismic Pharmaceuticals Announces the Enrollment of the First Patient in the Global Phase 3 Trial of Istaroxime in Cardiogenic Shock

Approximately 600 patients expected to be enrolled at clinical sites across the United States, Europe, China and South America

Global Phase 3 program, RESCUE HF-CS, builds upon three completed Phase 2 programs in which more than 350 patients enrolled

DURHAM, N.C., Sept. 9, 2026 /PRNewswire/ -- Seismic Pharmaceuticals, a biotechnology company dedicated to advancing novel treatments for heart failure, today announced the enrollment of the first patient in its global Phase 3 clinical trial evaluating istaroxime in patients with heart-failure-related cardiogenic shock. The trial, called RESCUE HF-CS, will recruit patients from around the globe and is designed to become the first ever drug approved to treat the life-threatening condition of cardiogenic shock. 

The approximately 600-patient study will be conducted at clinical sites across the United States, Europe, China and South America. The trial is designed to build upon the successful clinical results generated through four previously completed Phase 2 trials.  

Cardiogenic shock is a life-threatening condition that occurs when the heart is unable to pump enough blood to meet the body's needs, resulting in inadequate blood flow and oxygen delivery to vital organs. It may occur as a complication of acute heart failure or other serious cardiac conditions. Despite advances in critical care, cardiogenic shock continues to be associated with high rates of complications and mortality, underscoring the urgent need for new therapeutic options. There are no currently FDA-approved medications for the condition. 

Istaroxime is a novel, first-in-class calcitrope being developed to improve cardiac function and hemodynamic stability in patients with cardiogenic shock. Unlike conventional inotropic therapies, istaroxime has a unique dual mechanism of action designed to improve both systolic contraction and diastolic relaxation. Contrary to other therapies used off-label to treat cardiogenic shock, istaroxime does not increase myocardial oxygen demand, and it reduces heart rate and arrythmias.

"Cardiogenic shock remains one of the most lethal conditions we encounter in cardiovascular medicine, yet remarkably, we still lack an approved pharmacologic therapy specifically developed for this syndrome," said the study principal investigator Dr. Mandeep R. Mehra, MBBS, MSc, FRCP, The William Harvey Distinguished Chair in Advanced Cardiovascular Medicine, Mass General Brigham Heart & Vascular Institute, Professor of Medicine, Harvard Medical School. He added: "The launch of RESCUE HF-CS represents an important opportunity to determine whether istaroxime, with its distinctive ability to enhance cardiac performance while supporting diastolic relaxation, can meaningfully change the treatment paradigm for these critically ill patients."

The Phase 3 trial, RESCUE HF-CS, is expected to enroll approximately 600 patients with cardiogenic shock. Additional information regarding the trial's design, eligibility criteria and participating clinical sites will be available at ClinicalTrials.gov and other applicable clinical-trial registries.

About Istaroxime

Istaroxime is a novel, first-in-class Calcitrope with a dual mechanism of action - Na/K ATPase inhibitor and SERCA2a activator being developed for the treatment of cardiogenic shock. Istaroxime dual action leads to improvements in both cardiac contractility as evident by increased blood pressure and cardiac output improved diastolic function as evident by echocardiographic measures. In Phase 2 studies it reduced heart rate and in a subset of patients fitted  with  and is designed to improve cardiac function through a dual mechanism of action that increases with 72 continuous EKG monitoring significant reduction in measures of ventricular arrythmias in patients with cardiogenic shock.

About Seismic Pharmaceuticals

Seismic Pharmaceuticals is a biotechnology company dedicated to advancing novel treatments for heart failure. The company combines deep therapeutic expertise with a proven track record in acute heart failure drug development. Seismic Pharma's founding portfolio of drug candidates includes Seismic 101, a dual mechanism Na/K ATPase inhibitor and SERCA2a activator developed for acute and advanced HF, Seismic 102, a pure SERCA2a activator developed for acute and diastolic HF, and Seismic 103, a pan-SERCA activator for pulmonary hypertension. All three drugs are in pre-clinical development and expected to enter the clinical phase in the spring of 2027. The drugs are advanced with the support of Momentum Research, Inc., a greenhouse company that was involved with the development of many successful HF therapies, and a board of directors with extensive experience in successful heart-failure programs. Seismic is headquartered in Durham, North Carolina.

Media Contact

Gad Cotter
Seismic Pharmaceuticals
[email protected]

SOURCE Seismic Pharmaceuticals