Gossamer Bio Agrees to Acquire Respira Therapeutics for RT234
Gossamer Bio, Inc. has announced a significant step in its expansion efforts by entering into an option agreement to acquire Respira Therapeutics. The acquisition focuses on Respira’s lead candidate, RT234, an inhaled, on-demand formulation of vardenafil aimed at treating pulmonary hypertension (PH), including pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD).
The agreement was disclosed on September 25, 2025, and reflects Gossamer’s commitment to addressing the unmet needs of patients struggling with debilitating symptoms related to PH. According to Gossamer Bio’s Co-Founder, Chairman, and CEO, Faheem Hasnain, “There is a clear unmet need for an ‘as needed’ therapy in PAH and PH-ILD, where patients lack an option for rapid symptom management.”
Currently, the majority of patients suffering from PH have limited treatment options. RT234 is designed to provide acute relief from symptoms, such as breathlessness, which can limit daily activities and independence. Unlike existing therapies, RT234 aims to deliver rapid, on-demand symptom relief, complementing ongoing chronic treatments.
Under the terms of the option agreement, Gossamer will issue 2.5 million shares upon signing, which represents approximately 1% of Gossamer’s common shares outstanding. An additional 1.5 million shares will be issued once the option is exercised. Shareholders of Respira will also be eligible for milestone payments related to clinical, regulatory, and commercial achievements, along with a high single-digit royalty on potential net sales of RT234.
Gossamer plans to fund specific development expenses during the option period, which is expected to last for up to two years. This funding will focus on the chemistry, manufacturing, and controls (CMC) as well as device readiness for RT234. This structured approach aims to minimize immediate cash burn while preparing for further clinical development.
RT234, which is delivered via a dry-powder inhaler, represents a new approach in treating PAH and PH-ILD. Vardenafil, the active ingredient, is already an FDA-approved phosphodiesterase type 5 (PDE5) inhibitor used for other indications. Despite the availability of PDE5 inhibitors such as sildenafil and tadalafil for chronic treatment, there are currently no approved on-demand therapies for PAH or PH-ILD, making RT234 a potentially groundbreaking option.
In previous Phase 2 studies involving PAH patients, RT234 demonstrated promising results, showing rapid and clinically significant improvements in both hemodynamic and functional measures. These included reductions in pulmonary vascular resistance and improvements in mean pulmonary arterial pressure and cardiac output. The studies also reported enhancements in functional metrics, such as six-minute walk distance.
Gossamer Bio’s existing programs in pulmonary hypertension are expected to benefit from the addition of RT234, supporting the company’s strategy to build a comprehensive portfolio of therapies for PH. Positive interactions with the FDA have indicated a clear clinical development path for RT234. Should the option be exercised, Gossamer plans to pursue a 505(b)(2) regulatory pathway for RT234 in the United States, which could facilitate the approval process by leveraging existing data.
The acquisition of Respira Therapeutics is backed by Samsara BioCapital, a prominent investment firm focused on advancing innovative therapies for conditions with high unmet medical needs.
As Gossamer Bio continues to focus on its leading product, seralutinib, for PAH and PH-ILD, the company remains committed to meeting the needs of patients affected by pulmonary hypertension. The option agreement with Respira Therapeutics represents a strategic move to enhance its offerings and strengthen its position in the market.
Gossamer Bio has cautioned investors regarding forward-looking statements made in the announcement, emphasizing that actual results may vary due to various risks and uncertainties inherent in the biopharmaceutical industry.
