Chiesi, Gossamer to advance seralutinib for PAH, other disorders

Global Phase 3 PROSERA trial recruiting adults with PAH

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by Andrea Lobo |

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Chiesi Group has reached an agreement with Gossamer Bio to develop and market seralutinib for certain types of pulmonary hypertension (PH).

The agreement seeks to support the therapy’s ongoing testing in pulmonary arterial hypertension (PAH) and to accelerate its development for pulmonary hypertension associated with interstitial lung disease (PH-ILD).

Seralutinib’s safety and efficacy are currently being evaluated in the Phase 3 PROSERA trial (NCT05934526), which is recruiting adults with PAH in the U.S. and many other countries. The study is expected to be completed next year.

“Seralutinib is a potential paradigm shifting therapy in PAH and PH-ILD, and we could not be more excited to partner with Gossamer to develop and bring this therapy to patients world-wide,” Giuseppe Accogli, CEO of Chiesi Group, said in a company press release.

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“This partnership with Chiesi allows us to meaningfully deepen and rapidly accelerate our investment in seralutinib as a potential treatment for PAH, PH-ILD, and other indications of high unmet medical need,” said Faheem Hasnain, Gossamer’s co-founder, chairman, and CEO.

PH is characterized by high blood pressure in the pulmonary arteries, the blood vessels that transport blood through the lungs. The disease subtype PAH is marked by the narrowing of the pulmonary arteries and can have various causes, whereas lung scarring is observed in PH-ILD.

Seralutinib, inhaled directly into the lungs, is designed to block the activity of signaling proteins involved in the abnormal cell growth that leads to the narrowing of pulmonary arteries.

In preclinical studies using two animal models of severe PAH, the therapy was shown to effectively reduce pulmonary blood pressure, lung scarring, and right ventricle enlargement, a sign of PAH.

Then, data from the Phase 2 TORREY trial (NCT04456998) showed seralutinib treatment significantly reduced pulmonary vascular resistance, a measure of resistance to blood flow, in adults with PAH.

Promising results were also found on exercise capacity and heart structure, particularly in patients with more severe disease. Adverse events were generally mild to moderate in severity.

The PROSERA trial is estimated to enroll 350 adults with PAH, ages 18 to 75, randomly assigned to receive inhaled seralutinib at 90 mg or a placebo, twice daily, for up to 48 weeks (nearly one year).

The trial’s main goal is to assess changes in exercise capacity from the beginning of the trial (baseline) to week 24. Secondary measurements include changes in symptom severity, heart damage, lung function, and quality of life, as well as the proportion of patients who achieve clinical improvements or clinical worsening.

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Patients who complete the trial will be able to enter an open-label extension study, POSERA-EXT, in which all will receive the treatment.

The companies are also planning to start a Phase 3 study in PH-ILD in mid-2025 and to evaluate seralutinib for additional indications with high unmet medical needs.

“We are particularly thrilled that this collaboration enables seralutinib to move directly into a Phase 3 trial in PH-ILD, an indication with a paucity of available treatments, and a disease which we believe seralutinib is specifically designed to address,” Hasnain said.

Under the terms of the agreement, Gossamer will continue leading the development of seralutinib, and the companies will evenly split global development costs (except for the PROSERA study) and commercial profits.

Gossamer will lead U.S. commercialization, while Chiesi has exclusive rights to market seralutinib outside the U.S., for which it will pay Gossamer royalties on net sales.

Also, Chiesi will pay Gossamer $160 million as a reimbursement. In addition, Gossamer will be eligible to receive up to $146 million in regulatory milestones and $180 million in sales milestones.

A Conversation With Rare Disease Advocates