MannKind Corporation shares surged 38.3% on Wednesday after the company announced it is developing a dry powder inhalation (DPI) formulation of ralinepag - designated MNKD-1501 - for United Therapeutics Corporation under an expanded license and collaboration agreement dated August 2025.
The companies said United Therapeutics made an additional $5 million payment to MannKind in April to accelerate work on ralinepag DPI. Under the terms disclosed, MannKind could receive up to $35 million in development milestone payments and would be entitled to 10% royalties on net sales from any commercial product that results from the program.
United Therapeutics will act as the primary manufacturer for ralinepag DPI and will lead global development, regulatory submissions, and commercialization efforts. MannKind’s role is described as supporting formulation and supply activities, reflecting a collaborative but delineated division of responsibilities between the two companies.
Ralinepag is described in the announcement as an investigational prostacyclin receptor agonist. United Therapeutics reported in March that its long-term pivotal phase 3 ADVANCE OUTCOMES trial evaluating ralinepag extended-release tablets in pulmonary arterial hypertension met its primary endpoint with a high degree of statistical significance.
United Therapeutics initially intends to pursue approval of the DPI formulation for pulmonary arterial hypertension. The company also plans to explore additional indications including pulmonary hypertension associated with interstitial lung disease, idiopathic pulmonary fibrosis, and progressive pulmonary fibrosis, but those uses would require further clinical studies before any regulatory approval could be sought.
The announcement notes that ralinepag is not currently approved in any jurisdiction to treat these conditions. The arrangement builds on a prior relationship between the companies dating to a 2018 agreement that contributed to the U.S. Food and Drug Administration approval of Tyvaso DPI in May 2022. United Therapeutics reported Tyvaso DPI generated $1.3 billion in revenue in 2025.
Market reaction
Investors reacted strongly to the collaboration news, sending MannKind shares sharply higher on the day. The structure of the deal - including near-term cash support, milestone upside and ongoing royalty participation - appears to have been received positively by the market.
Operational roles and commercial path
The agreement places principal responsibility for manufacturing and the global development program with United Therapeutics, while MannKind’s contribution centers on formulation work and supplying material. United Therapeutics’ stated development path targets initial approval for pulmonary arterial hypertension and contemplates additional clinical programs for other pulmonary hypertension populations.
Context and outcome certainty
While the deal defines potential near-term payments and royalty terms, the realization of the full financial upside depends on successful development, regulatory approvals and commercial execution for ralinepag DPI. The companies’ previous collaboration that supported Tyvaso DPI’s approval is noted in the announcement but does not guarantee outcomes for the ralinepag program.