Upside for Insmed after Brinsupri’s first-in-class sales beat

Early launch numbers of Brinsupri are so strong that Insmed couldn’t wait for the J.P. Morgan Healthcare Conference to share them. The first-in-class inflammatory drug shattered Wall Street estimates in its first full quarter on the market, fueling fresh confidence in its blockbuster potential. Friday, Insmed announced preliminary Brinsupri total revenues of about $144.6 million in the fourth quarter of 2025. That sum beat Wall Street’s consensus projections by more than 150% in what Mizuho analysts called “a ginormous result.” Insmed’s share price jumped about 10% in premarket trading Jan. 9, although the stock has not fully recovered from the damage dealt by Brinsupri’s phase 2 trial flop in chronic rhinosinusitis without nasal polyps (CRwNP) in December. Approved by the FDA in August—and by the European Commission in November—to treat the chronic lung disease bronchiectasis, Brinsupri is the first DPP-1 inhibitor to reach the market and the first drug specifically cleared for the condition. The drug’s fourth quarter sales marked a significant acceleration from the $28.1 million it collected in the third quarter following its U.S. launch. Insmed plans to debut the drug in the European Union in the first half of 2026, with additional approvals anticipated in the U.K. and Japan this year. The “blowout sales performance,” meanwhile, has increased the confidence of William Blair analysts in Brinsupri’s “multi-blockbuster sales potential longer term,” according to a Jan. 9 note. The team expects the drug to reach blockbuster status in 2027 and has put its 2029 sales at nearly $3.3 billion. The Brinsupri sales beat was aided by a roughly 9% benefit from inventory build, according to a Insmed presentation. But this level was in line with the company’s expectations and was meaningfully lower than the 40% reported for the third quarter, the William Blair team noted. “[T] his is undoubtedly a clean beat,” Evercore ISI analysts wrote in a separate note Friday. The drug’s haul topped even the highest estimates of around $120 million to $125 million previously floated by investors, which accounted for inventory benefits, the analysts pointed out. Brinsupri added about 9,000 new patients in the fourth quarter, bringing its cumulative total to 11,550 as of the end of last year, according to Insmed. The number of prescribers also reached about 4,000, up from 1,700 in September. Despite the upbeat performance, Insmed in a Jan. 9 presentation tried to rein in expectations for 2026 with a few reasons for caution. These include routine patient out-of-pocket cost resets at the beginning of a year, as well as potential higher rebates and access criteria as payer contracts are finalized. While the CRwNP failure last year dented Insmed’s share price, analysts mostly remained bullish on Brinsupri’s potential. Even after the setback, TD Cowen analysts maintained modeled peak sales of $4.3 billion for the drug, according to a Dec. 17 note. Insmed expects a topline readout from another phase 2b study, called Cedar, of Brinsupri in hidradenitis suppurativa in the second quarter of 2026. DPP-1 has drawn increased interest from biopharma companies as a novel target for inflammatory diseases. Right before Brinsupri’s anticipated FDA go-ahead, inflammatory disease-focused startup Expedition Therapeutics licensed a DPP-1 candidate from Fosun Pharma in a potential $645 million deal. Back in 2023, Chiesi obtained a license to a DPP-1 inhibitor from China’s Haisco Pharmaceutical. Boehringer Ingelheim, too, has a potential rival DPP-1/CatC inhibitor, verducatib (BI 1291583), which was pushed into phase 3 testing in bronchiectasis last year. For its part, Insmed is also developing a next-generation DPP-1 drug, INS1033, and is moving toward the clinic in two large immunology indications—rheumatoid arthritis and inflammatory bowel disease—as the company expects to file an investigational new drug application with the FDA in 2026.