INSM Stock Plummets on Sinus Study Failure, Adds New Pipeline Asset

Shares of Insmed INSM lost nearly 20% in after-market trading on Wednesday after the company announced the failure of a mid-stage study evaluating Brinsupri (brensocatib) in chronic rhinosinusitis without nasal polyps (CRSsNP).

This phase IIb study, called BiRCh, failed to achieve either its primary or secondary efficacy endpoints. Although the drug was well-tolerated in patients, the results did not show any treatment benefit in patients compared with placebo, even at the highest dose level. Based on this outcome, Insmed decided to end development of Brinsupri in CRSsNP.

This announcement surprised investors, who had been expecting positive results from the BiRCh study. Insmed had achieved a significant milestone with Brinsupri in August, when the FDA approved it as the first treatment for non-cystic fibrosis (non-CF) bronchiectasis. Post this approval, it became the second marketed product in Insmed’s portfolio after Arikayce (approved to treat a rare lung disease infection).

Early commercial traction for Brinsupri has been encouraging — the drug generated $28 million in third-quarter 2025 sales despite receiving approval only in the middle of the quarter, reflecting strong initial uptake. Investors had expected this momentum to be further propelled by potential approval in new indications, such as CRSsNP, which have significant commercial potential.

The BiRCh study results have also made investors less enthused about the phase II CEDAR study, which is evaluating Brinsupri in the hidradenitis suppurativa (HS) indication. An update on this study is expected in the first half of 2026.

INSM Stock Performance

This marks the first major setback for Insmed in some time, as the company had delivered a series of positive updates leading up to this announcement. Following the sharp after-hours decline, the stock continued to trend lower in pre-market trading today.

Year to date, shares of Insmed are still up 187% compared with the industry’s 18% growth.

Insmed Expands Pipeline With New Acquisition

Alongside the BiRCh study results, Insmed announced that it has acquired an investigational monoclonal antibody, INS1148 (formerly OpSCF), from the privately-held biotech Opsidio. This drug is designed to address respiratory and immunological and inflammatory diseases by targeting a specific isoform of Stem Cell Factor SCF248.

Insmed plans to initially develop INS1148 in mid-stage studies for interstitial lung disease and moderate-to-severe asthma.

INSM’s Zacks Rank

Insmed currently carries a Zacks Rank #3 (Hold).

Insmed, Inc. Price

 

Insmed, Inc. price | Insmed, Inc. Quote

Key Picks Among Biotech Stocks

Some better-ranked stocks from the sector are ANI Pharmaceuticals ANIP and CorMedix CRMD, each sporting a Zacks Rank #1 (Strong Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.

In the past 60 days, estimates for ANI Pharmaceuticals’ 2025 earnings per share (EPS) have risen from $7.29 to $7.56. EPS estimates for 2026 have increased from $7.81 to $8.08 during the same period. Year to date, shares of ANIP have surged 49%.

ANIP’s earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 21.24%.

Estimates for CorMedix’s 2025 EPS have increased from $1.85 to $2.87 over the past 60 days, while the same for 2026 has increased from $2.49 to $2.88. CRMD shares have risen 41% year to date.

CorMedix’s earnings beat estimates in each of the trailing four quarters, delivering an average surprise of 27.04%.

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This article originally published on Zacks Investment Research (zacks.com).

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