ROIV Mosliciguat: 56% PVR Readout in PH-ILD Phase 2

Roivant keeps buying cheap cast-offs and turning them into real programs. It paid Bayer roughly $14 million for an inhaled soluble guanylate cyclase activator that the German giant had deprioritized. That drug, mosliciguat, just posted the largest pulmonary vascular resistance reduction ever recorded in a controlled pulmonary hypertension trial. The commercial question is whether it can beat the one drug already approved in the disease, and the answer will not be known until a Phase 3 trial reads out years from now.

The 56.3% number, in context

The Phase 2 PHocus trial randomized adults with pulmonary hypertension associated with interstitial lung disease (PH-ILD) to once-daily inhaled mosliciguat or placebo. The primary endpoint was the change from baseline in pulmonary vascular resistance at Week 16, measured by right heart catheterization. Mosliciguat delivered a 56.3% placebo-adjusted PVR reduction (negative 51.3% for mosliciguat versus positive 6.6% for placebo, p less than 0.0001).

Context matters more than the headline. In the only successful registrational trial in this disease, inhaled treprostinil’s INCREASE study, the primary endpoint was not PVR at all. It was six-minute walk distance, which improved by 31.1 meters versus placebo. PVR is a hemodynamic surrogate that matters to the FDA’s thinking but is not itself an approval endpoint. Roivant is correct that a 56% PVR reduction is the largest ever in any randomized controlled PH trial, but it is a measure of how well the drug opens the pulmonary vessels, not proof that patients walk further, breathe easier, or stay out of the hospital. Those are what the Phase 3 PHrontier study has to show.

The trial design is otherwise clean. Randomized, double-blind, placebo-controlled, global, with a 2:1 randomization to active drug. The safety signal was described as well tolerated, and an inhaled route means lower systemic exposure than the oral sGC stimulator riociguat, whose PH-ILD trial was terminated early for increased hospitalization and mortality. That route difference is the whole reason mosliciguat can try where riociguat failed.

The market only has one approved drug, and it is aging into its own label expansion

PH-ILD is a small, deadly niche. The market across the seven major markets was worth roughly $3 billion in 2025 and is growing at a high single-digit rate. The only FDA-approved therapy is United Therapeutics’ inhaled treprostinil, sold as Tyvaso, which won approval on the INCREASE trial in 2021. Tyvaso is a prostacyclin analogue that requires four-times-daily dosing and dose titration, and it has been the monopoly in the space ever since.

The competitive picture is about to get more crowded, and not just from Roivant. United Therapeutics is itself trying to expand Tyvaso into idiopathic pulmonary fibrosis, with an sNDA accepted by the FDA in September 2026 and a decision expected in late April 2027, covered in the Tyvaso IPF piece. If that label expansion lands, United Therapeutics would own the IPF and PH-ILD overlap patient, the exact population mosliciguat’s Phase 3 will enroll. The two programs are racing to be the inhaled standard in fibrotic lung disease with pulmonary vascular involvement.

Mosliciguat’s edge is mechanism. It is an sGC activator, meaning it stimulates the nitric oxide pathway directly and does not require the prostacyclin pathway, which is why it can be dosed once daily instead of four times daily and why it may avoid the tolerability headaches of prostacyclins. If the Phase 3 shows a six-minute walk benefit comparable to INCREASE’s 31 meters with once-daily dosing and a clean safety profile, it wins on convenience alone. The 56% PVR number is the reason to believe the functional benefit will be there, but it is not a substitute for it.

Where this sits in a $30 billion company

Roivant closed at $41.81 with a $30.2 billion market cap. The company reported $4.3 billion in cash and marketable securities as of March 31, 2026, with runway into profitability. The valuation is no longer about a single asset. LISRAYA (brepocitinib) won FDA approval for dermatomyositis in August 2026 and is now on the market, with the launch detailed in the LISRAYA approval piece. The same drug has a Phase 3 readout in non-infectious uveitis expected in the second half of 2026, plus a Phase 2b/3 in lichen planopilaris underway. IMVT-1402, the anti-FcRn antibody, is running across IgG-mediated autoimmune disease.

Mosliciguat is the pulmonary leg of that story. A company with $4.3 billion in cash, an approved drug generating revenue, and three additional late-stage readouts within twelve months does not live or die on a Phase 2 PVR number. The stock moved about 5.6% on the news, which is roughly the right reaction for a secondary pipeline asset inside a diversified Vant-holding company. The brepocitinib path from PDUFA to approval is instructive here, and it is worth reviewing the brepocitinib pre-approval analysis to see how Roivant’s Vant structure actually converts a positive readout into shareholder value.

The comp that matters is United Therapeutics, which trades at roughly a $22 billion market cap on the back of Tyvaso and its prostacyclin franchise. Roivant is valued 37% higher than the company whose monopoly mosliciguat would break. That gap is justified by Roivant’s broader pipeline and cash, but it also means the PH-ILD upside is not what is driving the stock. Mosliciguat is option value, not thesis value.

Risks

The endpoint gap is the risk that matters. A 56% PVR reduction at Week 16 is real, but the FDA will judge Phase 3 on functional outcomes. If the six-minute walk benefit lands below INCREASE’s 31-meter bar, or if the once-daily convenience is offset by a narrower effect, mosliciguat becomes a me-too instead of a category winner. The sGC class has a graveyard in this exact disease, and the burden of proof is on the new mechanism.

Then there is timing. The Phase 3 PHrontier study is ongoing, and PH-ILD trials are slow to enroll because the disease is rare and the right heart catheterization endpoint is burdensome. This is not a 2026 or even 2027 catalyst in all likelihood. Money parked in Roivant for mosliciguat is money waiting through at least two of the company’s nearer-term readouts first.

Further out, competition from the incumbent adds another risk. United Therapeutics’ Tyvaso IPF sNDA decision lands around April 2027, before mosliciguat’s Phase 3 completes. If Tyvaso expands its label first, it hardens the incumbent’s position and raises the bar for any challenger to displace it on payer formularies and physician habit.

Verdict

Do not buy Roivant for mosliciguat. The drug is a legitimate Phase 2 winner with a real shot at becoming the second approved therapy in PH-ILD, but it is one leg of a company already priced at $30 billion with a full pipeline of nearer catalysts. The correct trade is to own Roivant for the LISRAYA launch and the uveitis readout, and treat mosliciguat’s Phase 3 as a free option that pays off years from now.

The sharper read is on United Therapeutics. If you want to express the PH-ILD thesis today, the incumbent with the approved drug and the pending IPF label expansion is the purer vehicle. Mosliciguat’s 56.3% is a warning shot across Tyvaso’s bow, not a knockout. Hold Roivant, and watch PHrontier’s six-minute walk data, not the PVR number, for the answer.

ClinicalTrials.gov: PHocus · Roivant PHocus press release