Gossamer Bio Inc. (NASDAQ:GOSS) dropped during early trading on Monday after the company shared topline results from the Phase 3 PROSERA study evaluating seralutinib in pulmonary arterial hypertension.

PAH is defined by high blood pressure in the lung arteries due to narrowed, damaged, or destroyed vessels, forcing the heart’s right side to overwork and potentially fail.

The company reported that, while it narrowly missed a key statistical threshold, the results still indicate that seralutinib is an active treatment option. The company plans to discuss the findings with the FDA and will present data demonstrating greater activity in patients with advanced disease.

Disappointing Trial Data

At Week 24, patients receiving seralutinib showed a median change of +28.2 meters in the Six-Minute Walk Distance (6MWD) from baseline, compared to a +13.5 meters change for the placebo group.

The estimated treatment effect was +13.3 meters, with a p-value of 0.0320, which, despite not meeting the prespecified threshold, indicates a significant improvement in patient mobility.

In addition, in patients with connective tissue disease–associated PAH (CTD‑APAH), seralutinib demonstrated a robust improvement in six‑minute walk distance, achieving a placebo‑adjusted gain of +37.0 meters at Week 24 (n = 87; p=0.0104), indicating a strong treatment effect in this clinically challenging subgroup.

The company said seralutinib delivered a signal in the prespecified intermediate‑ and high‑risk subgroup (n = 234), as defined by the REVEAL 2 Lite Risk Score ≥ 6 at screening, with a +20.0m placebo‑adjusted improvement in 6MWD (p = 0.0207).

Three of four key secondary endpoints also demonstrated a p-value below 0.0125, underscoring seralutinib’s activity in patients with higher risk.

Overall, seralutinib was generally well tolerated in the PROSERA Study.

Next Steps

Gossamer Bio expects to meet with the U.S. FDA to discuss the path forward for seralutinib in pulmonary arterial hypertension.

The company is pausing enrollment into the SERANATA Study to evaluate the impact of PROSERA results, particularly regional discrepancies in placebo response.

Additionally, PROSERA results from the CT functional respiratory imaging (FRI) substudy are expected in the coming weeks and are anticipated to provide additional insight into seralutinib’s treatment effect, including pulmonary blood volume distribution.

Earnings & Analyst Outlook

The next major catalyst for the stock arrives with the March 12, 2026 earnings report.

• EPS Estimate: Loss of 19 cents (Up from Loss of 15 cents)
• Revenue Estimate: $7.56 million (Down from $9.38 million)

Analyst Consensus & Recent Actions: The stock carries a Buy Rating with an average price target of $8.38. Recent analyst moves include:

• Barclays: Initiated with Overweight (Target $9.00) (January 28)
• HC Wainwright & Co.: Buy (Maintains Target to $10.00) (January 22)
• Cantor Fitzgerald: Overweight (September 11, 2025)

GOSS Price Action: Gossamer Bio shares were down 77.12% at $0.59 at the time of publication on Monday, according to Benzinga Pro data.

Photo: jittawit21/Shutterstock

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