United Therapeutics, the Silver Spring, Maryland, and Research Triangle Park, North Carolina, developer of treprostinil-based therapies for lung disease, announced on October 19, 2026 that the U.S. Food and Drug Administration (FDA) has cleared it to proceed under its investigational new drug (IND) application with SUMMIT, a Phase 2 clinical trial. The study will test an investigational soft mist inhaler (SMI) version of treprostinil in people with pulmonary hypertension associated with chronic obstructive pulmonary disease (PH-COPD). No therapy is currently approved for that condition, and the company says treprostinil SMI could become the first one if later studies succeed.
Inside the SUMMIT Study
SUMMIT is a 16-week, double-blind study that will enroll approximately 40 patients with PH-COPD. Its main goal is to assess safety and tolerability. Secondary endpoints will look at exercise capacity and N-terminal pro-B-type natriuretic peptide (NT-proBNP), a biomarker for heart failure. Eligible participants can roll into an open-label extension study measuring long-term safety, tolerability and efficacy. If SUMMIT succeeds, the company expects to begin a Phase 3 registration study in 2028. “PH-COPD is a serious, life-threatening condition with no approved treatments. We believe that inhaled treprostinil, delivered via a soft mist inhaler, may benefit the carefully defined SUMMIT PH-COPD patient population by directly targeting the pulmonary vasculature. Our hope is that treprostinil SMI will offer meaningful benefit and reduce disease burden for PH-COPD patients who deserve a treatment option that addresses their significant unmet needs,” said Leigh Peterson, Ph.D., head of pharmaceutical and xenograft development at United Therapeutics.
Why the Company Is Betting on a Soft Mist
According to United Therapeutics, people with PH-COPD tend to be susceptible to cough and bronchospasm from inhaled therapies, and a soft mist formulation may be easier for them to tolerate. The handheld device delivers a preserved treprostinil solution in a single breath, four times a day. It will be offered in several dose strengths during the trial so physicians can titrate each patient. One cartridge is designed to last up to two weeks, and the product can be kept at room temperature. The company’s second-quarter 2026 report said it planned to file a new drug application (NDA) for treprostinil SMI by year end, and its quarterly SEC filing explains that this NDA would target the indications nebulized Tyvaso already holds, pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD), backed by pharmacokinetic bridging studies. Company leadership introduced the product under the name Tresmi on a February earnings call, though the SUMMIT announcement does not use that name. Treprostinil SMI remains investigational and is not approved anywhere for any use.
A Second Attempt at PH-COPD
SUMMIT is not United Therapeutics’ first try in this population, a point the announcement leaves out. The company’s Phase 3 PERFECT study of nebulized Tyvaso in PH-COPD began in 2018 and was terminated in September 2022 on the recommendation of its independent Data Safety Monitoring Committee. When the results were published in the European Respiratory Journal, the investigators concluded that the risk-benefit picture did not support continuing and that the findings did not support inhaled treprostinil as a viable PH-COPD treatment. A 2025 review in Breathe reported that PERFECT was halted because the drug increased serious adverse events in these patients. The new trial uses a different delivery device, puts safety and tolerability first, and targets what Dr. Peterson calls a “carefully defined” patient group. The company has not publicly detailed how SUMMIT’s eligibility criteria differ from PERFECT’s.
What Is Riding on the Program
United Therapeutics estimates that 400,000 to 800,000 people in the U.S. live with PH-COPD. Leadership is framing the indication as a major growth opportunity. “I believe this development will lead to an exponential inflection point for United Therapeutics,” said Martine Rothblatt, Ph.D., its Chairperson and Chief Executive Officer. “We estimate PH-COPD could impact five to ten times the number of patients than the conditions all of our current therapies are approved to treat today. Upon successful completion of the SUMMIT program and approval by the FDA, we expect United Therapeutics will become a several times larger company than it is today.” These are company projections that depend on a small Phase 2 study, a future Phase 3 trial and an FDA decision. The field is also getting company: Morrisville, North Carolina’s Liquidia has named PH-COPD among the future indications it is pursuing for its own inhaled treprostinil products. Beyond PH-COPD, United Therapeutics plans to develop treprostinil SMI for PAH, PH-ILD, idiopathic pulmonary fibrosis and progressive pulmonary fibrosis.
Roots in Maryland and the Research Triangle
United Therapeutics lists its principal executive offices in Silver Spring in its SEC filings, and its announcements carry a joint Silver Spring and Research Triangle Park dateline. The company also has a Virginia footprint: it opened its first designated pathogen-free xenograft facility in Christiansburg, Virginia, in 2024. Rothblatt founded the company to find a cure for her daughter’s pulmonary arterial hypertension. It is organized as a public benefit corporation and also works on manufactured and xenotransplant organs.
About United Therapeutics
Founded by CEO Martine Rothblatt to discover a cure for her daughter’s life-threatening rare disease, pulmonary arterial hypertension, United Therapeutics transforms the treatment of rare diseases and pioneers alternatives to expand the supply of transplantable organs. From our innovative therapies to our groundbreaking manufactured organs, we are bold and unconventional. We move quickly from scientific theory to practical technologies that can save lives. As a public benefit corporation, even our legal structure reflects our commitments. We serve patients, act with integrity, create long-term shareholder value, and operate with sustainable practices that protect the future we are working to build. Visit them at www.unither.com
