In early clinical testing, a single inhaled dose of mosliciguat reduced pulmonary vascular resistance by up to 38% and was well tolerated. Operationally, Pulmovant has now completed enrollment of approximately 120 adults with PH-ILD into the randomized, double-blind, placebo-controlled PHocus Phase 2 trial in under 12 months, with topline data targeted for the second half of 2026.
The core development is speed and focus: Pulmovant, a Roivant company, closed global enrollment for PHocus and is running PHactor, an open-label study assessing tolerability when mosliciguat is layered on inhaled treprostinil. Mosliciguat is a once-daily, inhaled sGC activator aimed at delivering targeted pulmonary vasodilation while limiting systemic exposure. PHocus is designed to establish safety and efficacy in a setting where treatment adoption is shaped by symptoms, oxygenation, functional capacity, and exacerbation risk, and where right heart catheterization capacity and ILD phenotyping drive site throughput.
Strategically, this is a bid to carve space alongside, not against, the entrenched prostacyclin backbone in PH-ILD. Inhaled treprostinil has become the reference therapy, but it is dosed multiple times daily and remains burdensome for some patients. A once-daily inhaled agent hitting the NO–sGC–cGMP pathway could offer additive or alternative benefit with simpler operational demands. The tension is the class history: systemic sGC stimulators faced safety concerns in interstitial lung disease, sharpening regulatory scrutiny on gas exchange, hypotension, and clinical worsening. Pulmovant’s thesis is that lung-targeted delivery of an sGC activator can capture hemodynamic benefit with fewer systemic liabilities; the Phase 2 program is designed to test that claim and to map a combination path with background treprostinil that mirrors real-world practice.
For sites, the rapid enrollment is a readout on network selection and patient pull at specialized PH-ILD centers. It also signals rising protocol density in Group 3 PH and intensifying competition for phenotyped ILD patients with right heart catheterization capacity. Device training, inhalation technique standardization, and home-use adherence monitoring will be nontrivial operational elements, though once-daily dosing may reduce patient burden and visit friction relative to multi-dose regimens. For sponsors and CROs, the cadence underscores that streamlined inhaled protocols with pragmatic background therapy allowances can accelerate screening and randomization in rare cardiopulmonary populations. Regulators will anchor on functional and hemodynamic coherence and on oxygenation safety signals, particularly when adding mosliciguat to prostacyclin therapy. Payers will ultimately weigh any efficacy gains and tolerability advantages against the convenience and established outcomes of treprostinil, with dosing simplicity a potential differentiator if outcomes are comparable.
The next inflection point is the PHocus readout. Watch for concordance between exercise capacity, hemodynamics, and biomarkers, as well as any effect on clinical worsening and hospitalization. Safety with concomitant inhaled treprostinil in PHactor will be closely parsed, given historical concerns with vasodilatory mechanisms in ILD. If the signal is robust, Pulmovant will need to quickly lock a Phase 3 design that addresses background therapy stratification, ILD subtype balance, and global site scalability, alongside device supply and adherence telemetry. The unresolved questions are whether targeted inhaled sGC activation can deliver a clinically meaningful, regulator-ready profile in PH-ILD and whether once-daily convenience can translate into adoption in a market oriented around prostacyclin practice patterns. The answer will determine if this becomes an add-on strategy within current care or a credible alternative path that reshapes trial and treatment algorithms in Group 3 PH.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
