Tectonic expects early data from TX45 trial in coming months
APEX study recruiting adults with PH-FHpEF; trial planned for PH-ILD
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Top-line results from a Phase 2 trial of TX45, Tectonic Therapeutics’ experimental drug for pulmonary hypertension associated with heart failure with preserved ejection fraction (PH-HFpEF), are expected late this year or early next year, the company said.
The trial, APEX (NCT06616974), is nearly fully enrolled, but is still recruiting adults with PH-HFpEF at sites in the U.S. and abroad. Tectonic has started another Phase 2 trial, ALPINE (NCT07473700). ALPINE will be the first trial to test TX45 for PH related to interstitial lung disease (PH-ILD).
“During Q1 2026, we made meaningful progress advancing [TX45] across key clinical milestones, including … continued dosing of patients in the TX45 APEX Phase 2 trial and initiating our TX45 ALPINE Phase 2 trial in PH-ILD,” Alise Reicin, MD, president and CEO of Tectonic, said in a company press release. “Looking ahead, we remain focused on executing our ongoing clinical trials.”
In PH, the pulmonary arteries (the blood vessels that supply the lungs) develop structural alterations that increase blood pressure. This can strain the heart, reducing blood flow throughout the body and limiting oxygen delivery to cells.
There are several types of PH, which the World Health Organization classifies based on their underlying causes. PH-HFpEF is part of group 2 PH, and is characterized by the heart muscle contracting normally, but its left ventricle not relaxing properly between heartbeats. In PH-ILD, part of group 3 PH, the rise in pulmonary artery pressure is related to lung inflammation and scarring.
Relaxin treatment
TX45 contains a long-lasting version of the relaxin hormone. Relaxin typically helps relax blood vessels, increase heart output, and reduce scarring and inflammation. Tectonic expects that increasing relaxin activity with TX45 will decrease pulmonary artery pressure and ease PH symptoms.
The APEX trial aims to test TX45 in about 180 adults with PH-HFpEF. It is based on Phase 1 trial results showing that TX45 treatment improved heart function and blood flow in this type of PH.
Participants are randomly assigned to receive either subcutaneous (under-the-skin) injections of TX45 or a placebo for 24 weeks (about six months). Those receiving the treatment are assigned to one of two TX45 dosage groups. One group will be dosed every two weeks, and the other alternates between the active medication and the placebo every two weeks (receiving TX45 every four weeks).
Investigators will measure pulmonary vascular resistance (PVR), a measure of how difficult it is for the heart to push blood through the pulmonary arteries, before and after treatment. Assessing changes in PVR in participants with a severe PH-HFpEF subtype called combined pre- and post-capillary PH is one of the main goals of the study. Other primary outcomes include safety and results of physical examinations.
ALPINE is a smaller, shorter study involving about 25 adults with PH-ILD. All participants will receive subcutaneous doses of TX45 every four weeks up to week 13.
Like APEX, the main goals of ALPINE include recording safety concerns and testing changes in PVR. The first ALPINE site began screening participants for inclusion in March. The study will ultimately have sites in the U.S. and Europe. People ages 18 to 80 with a confirmed diagnosis of PH-ILD may be eligible if they meet certain clinical criteria.
