Ironwood Reports 97% LINZESS Sales Surge, Advances Apraglutide Toward STARS-2 Trial Initiation
Key Insights
Ironwood Pharmaceuticals reported first quarter 2026 LINZESS U.S. net sales of $272.5 million, a 97% year-over-year increase driven by improved net price and 5% prescription demand growth.
The FDA accepted a supplemental NDA for LINZESS in children aged 2–5 years with functional constipation (search), with a priority review PDUFA date of May 24, 2026.
Apraglutide's confirmatory Phase III STARS-2 trial is on track for site initiation in Q2 2026, targeting 124 SBS-IF patients with a primary endpoint of relative parenteral support volume change at week 24.
Ironwood Pharmaceuticals opened 2026 with a commanding financial performance, reporting first quarter LINZESS U.S. net sales of $272.5 million — a 97% increase over the same period in 2025. The surge was propelled by significantly improved net price realization and a 5% year-over-year increase in prescription demand, positioning the brand to reclaim blockbuster status with projected record annual U.S. net sales since launch.
Total revenue for the quarter reached $106.5 million, while U.S. brand collaboration revenue climbed to $104.2 million, representing a 169% increase from $38.8 million in the prior-year quarter. GAAP net income was $40.8 million, and adjusted EBITDA came in at $76.7 million.
Net Price Dynamics and Demand Growth
The improved net price reflected two primary drivers. First, the elimination of inflationary rebates across channels, including Medicaid, provided a structural benefit expected to persist throughout 2026. Second, favorable timing of gross-to-net rebate reserves relative to the first quarter of 2025 contributed to the quarter's strength.
"We expect reduced variability in sequential quarterly LINZESS U.S. net sales than occurred in 2025 as a result of more consistent net price across channels in 2026," said Tammi Gaskins, Chief Commercial Officer. Management emphasized that the 5% prescription demand growth in the first quarter was slightly above the full-year outlook of low single-digit percentage growth, a dynamic anticipated and factored into annual guidance.
Pediatric Expansion on the Horizon
The FDA accepted a supplemental new drug application for LINZESS (linaclotide) (search) for the treatment of functional constipation (search) in patients aged 2 to 5 years, granting priority review with a PDUFA target action date of May 24, 2026. LINZESS is currently the only FDA-approved drug for children 7 years and older with irritable bowel syndrome with constipation and for children aged 6 to 17 years with functional constipation. If approved, the new pediatric indication would further broaden the drug's clinical utility in younger age groups.
Chief Executive Officer Thomas McCourt noted, "We look forward to hearing from the FDA in the coming weeks." While the pediatric opportunity is viewed as incremental, commercial leadership emphasized that the adult IBS-C and CIC segments remain the central drivers of LINZESS demand growth.
Apraglutide: STARS-2 Trial and Market Opportunity
Ironwood advanced its rare disease pipeline with apraglutide, a next-generation long-acting synthetic GLP-2 (search) analog for short bowel syndrome with intestinal failure (SBS-IF) (search). The confirmatory Phase III STARS-2 trial remains on track for clinical site initiation in the second quarter of 2026.
STARS-2 will enroll 124 SBS-IF patients in a 1:1 randomization, including both stoma and colon-in-continuity patients. The primary endpoint is relative parenteral support volume change from baseline at week 24 for the overall population. Secondary endpoints include clinical response defined as a 20% reduction in parenteral support volume, number of days off parenteral support per week, and enteral autonomy.
Chief Medical Officer Michael Shetzline explained that the trial design reflects FDA interactions: "We're not formally stratifying. This was actually an outcome from our discussions with the agency." Enrollment will be tracked to ensure adequate representation of both patient subgroups.
At Digestive Disease Week (DDW) 2026, Ironwood presented pooled long-term safety data from the STARS clinical program, demonstrating a tolerability and safety profile consistent with previous studies, low discontinuation rates due to treatment-emergent adverse events, and no new safety observations. Additionally, data from the STARS Extend long-term extension study showed that approximately 20% of patients achieved enteral autonomy as of January 2025.
The LANDMARK survey, also presented at DDW, revealed that 46% of providers prioritized reducing the number of days per week on total parenteral nutrition as a key attribute for future therapies, while 30% prioritized reducing TPN hours per day.
Commercial Potential in SBS-IF
Ironwood estimates approximately 18,000 SBS-IF patients across the U.S., Europe, and Japan, with more than 8,000 patients in the U.S. dependent on parenteral support three or more days per week. This group represents a total addressable market exceeding $4 billion in the U.S. Currently, an estimated 1,500 to 2,000 patients receive GLP-2 (search) therapy at any given time.
"Based on apraglutide's clinical profile and our market research, we believe that apraglutide has the potential to increase the number of GLP-2 (search) treated patients, extend days on therapy, and achieve greater than $700 million in peak net sales in the U.S.," stated Gaskins.
Financial Position and 2026 Guidance
Ironwood ended the first quarter with $220.5 million in cash and cash equivalents, plus $105.8 million in accounts receivable expected to be collected before the June 15 convertible note maturity. Management plans to repay the 2026 convertible note in cash at maturity and reduce total debt to approximately $300 million by year-end — less than one times expected 2026 adjusted EBITDA.
Full-year 2026 guidance was reiterated: LINZESS U.S. net sales of $1.125 billion to $1.175 billion, Ironwood revenue of $450 million to $475 million, and adjusted EBITDA greater than $300 million. R&D expenses are expected to ramp through the remainder of 2026 as STARS-2 activities accelerate.