Ironwood Late-Breaker Oral Presentation at Digestive Disease Week® Reinforces Potential of Once-Weekly Apraglutide for Adults with Short Bowel Syndrome with Intestinal Failure (SBS-IF)

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– New data highlight both stoma and colon-in-continuity (CIC) patients drove the positive primary endpoint with significant relative change from baseline in weekly parenteral support (PS) volume reduction at week 24 – – Additional secondary endpoints show significant increases in days off PS and clinical responder rates with apraglutide, including achieving enteral autonomy in both stoma and CIC patients – – Data from largest GLP-2 Phase III study to date adds to body of evidence on safety and efficacy of once-weekly apraglutide in adults with SBS-IF – – New details on safety and tolerability to be presented; showing apraglutide to be well tolerated with a safety profile consistent with previously reported apraglutide studies in this patient population – BOSTON --(BUSINESS WIRE)-- Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused healthcare company, will present late-breaking data during the 2024 Digestive Disease Week® (DDW) meeting from its pivotal Phase III clinical trial, STARS, which evaluated the efficacy and safety of once-weekly subcutaneous apraglutide in adult patients with short bowel syndrome with intestinal failure (SBS-IF). These findings build on the positive topline data that Ironwood previously announced in February 2024 . Based on these results, the company is working to submit a new drug application (NDA) to the U.S. Food and Drug Administration (FDA) and marketing applications to other regulatory agencies for apraglutide for the treatment of adult patients with SBS who are dependent on parenteral support (PS). SBS-IF, a rare chronic debilitating malabsorptive condition in which patients are dependent on PS, affects an estimated 18,000 adult patients in the U.S. , Europe , and Japan . Apraglutide is the first and only investigational once-weekly GLP-2 analog that has successfully demonstrated positive results in a Phase III placebo-controlled study. The late-breaking data at DDW are from the largest global SBS-IF clinical trial conducted to date and are being shared during an oral presentation titled “Efficacy and Safety of Apraglutide Once-Weekly in Patients with Short Bowel Syndrome and Intestinal Failure (SBS-IF): Results from the STARS Study - A Global Phase 3 Double-Blind, Randomized, Placebo-Controlled Trial.” Ironwood previously reported that the STARS clinical trial met its primary endpoint of relative change from baseline in actual weekly PS volume at week 24 vs. placebo (-25.5% vs. -12.5%; p=0.001), driven by both stoma and colon-in-continuity subpopulations. Treatment effect with relative PS volume reduction was observed from week 8 onward (-8% vs -1.6% placebo, p=0.002). Findings from the late-breaking presentation include: Significantly more apraglutide-patients gained additional days off from PS per week at week 24 versus placebo (≥2 days: 24.5% vs 11.3%, p=0.021; ≥3 days: 11.8% vs 1.9%, p=0.006) Significantly more apraglutide-treated patients in the overall and the stoma populations were clinical responders and clinical high responders (defined as ≥20% and ≥40% PS volume reduction, respectively), at both weeks 20 and 24 versus placebo Overall population: Clinical responders 42.7% vs 20.8%, p=0.003; Clinical high responders 22.7% vs 9.4%, p=0.018 Stoma subpopulation: clinical responders 40.7% vs 15.4%, p=0.02; clinical high responders 20.4% vs 0%, p=0.009 Seven apraglutide-treated patients achieved enteral autonomy (three in the stoma subpopulation, four in the colon-in-continuity subpopulation) by week 24 (6.4% apraglutide vs 0% placebo, p=0.006). Three additional colon-in-continuity patients achieved enteral autonomy by week 48: 7/56 [12.5%] apraglutide vs 2/27 placebo [7.4%], p=0.387. “Given the burden that parenteral support places on people living with SBS-IF, the goal of treatment is to importantly gain additional days off PS, and ultimately achieve enteral autonomy in those who can achieve it,” said Kishore R Iyer, MBBS, FRCS (Eng), FACS, Director of Adult and Pediatric Intestine Rehabilitation & Transplantation at The Mount Sinai Hospital in New York , Coordinating Principal Investigator of the trial, paid scientific advisor to Ironwood and chair of the scientific steering committee for the STARS clinical trial. “The fact that some CIC and stoma patients on apraglutide achieved enteral autonomy at week 24 and sustained that autonomy through 48 weeks is an important outcome and demonstrates the potential of apraglutide for these patients.” Apraglutide also demonstrated statistical significance on two key secondary endpoints, with more patients in the combined population achieving at least one day/week off PS relative to baseline at week 24 versus placebo (43.0% vs. 27.5%; p=0.040) and more patients treated with apraglutide versus placebo demonstrating improvement in relative change from baseline in actual weekly PS volume at week 24 in the stoma subpopulation (-25.6% vs. -7.8%; p2,000 adults with IBS-C. Treatment-emergent adverse events were similar in both age groups and were consistent with the known safety profile of linaclotide in patients with IBS-C. “Assessing US Healthcare Disparities in IBS Diagnosis: A National Survey Analysis” (presentation number Tu1027) will be presented by Christopher V Almario, M.D., MSHPM, Cedars Sinai Medical Center , Los Angeles, CA , summarizing survey data from nearly 90,000 adults in the US. The study analyzed healthcare-seeking behavior, including the likelihood of seeing a healthcare provider (HCP) and the type of HCP seen. Respondents who identified as Black or African American were less likely to be diagnosed with IBS than those who identified as White, even after controlling for potential confounding variables, such as socioeconomic status and symptom severity. About STARS The STARS (STudy of ApRaglutide in SBS) pivotal Phase III trial represents the largest Phase III trial in SBS-IF to date. This global, multicenter, double-blind, randomized, placebo-controlled trial evaluated the efficacy and safety of weekly subcutaneous injections of apraglutide in adult patients with SBS-IF. STARS randomized 164 patients 2:1 and 163 were dosed to receive either once-weekly apraglutide or placebo. Patients were stratified approximately 50/50 by remnant bowel anatomy (stoma vs. colon-in continuity) and evaluated over 24 weeks (stoma and colon-in-continuity subpopulations) and 48 weeks (colon-in-continuity subpopulation only). The primary endpoint was relative change from baseline in actual weekly PS volume at week 24. Key secondary endpoints included patients who achieved a reduction from baseline of at least 1 day/week off PS at week 24 (overall population); relative change from baseline in actual weekly PS volume at week 24 (stoma subpopulation); patients who achieved a reduction from baseline of at least 1 day/week off PS at week 48 (colon-in-continuity subpopulation); and patients reaching enteral autonomy at week 48 (colon-in-continuity subpopulation). The study was conducted in 18 countries with enrollment from 68 study sites. About STARS Nutrition STARS Nutrition is the first-ever study to prospectively evaluate the clinical benefit of a GLP-2 analog specifically in patients with colon-in-continuity. This multicenter, open-label Phase II metabolic balance study was designed to evaluate the effect of once-weekly apraglutide 5-mg subcutaneous injection on intestinal absorption in SBS-IF patients with colon-in-continuity at 52 weeks. Safety and parameters indicative of clinical efficacy, including PS volume and energy content reduction, were assessed. The study enrolled nine adult patients with a mean age of 46.8 years. About Short Bowel Syndrome SBS is a serious and chronic condition where there is diminished absorptive capacity for fluids and/or nutrients, sometimes requiring dependence on parenteral support to maintain health. Short bowel syndrome typically occurs because of extensive intestinal resection, and patients with SBS who are chronically dependent on parenteral support, also referred to as SBS with intestinal failure (SBS-IF), often experience significant quality of life impact and are at risk of severe complications such as infection. An estimated 18,000 adult patients suffer from SBS-IF in the U.S. , Europe and Japan , and have chronic dependence on PS, which significantly impacts quality of life and carries the risk of severe complications such as infection. Those with the most severe SBS-IF require PS infusions for up to 10 to 15 hours per day. SBS-IF is associated with frequent complications, significant morbidity and mortality, high economic burden and an impaired quality of life. About Apraglutide Apraglutide is an investigational, next-generation, long-acting synthetic GLP-2 analog being developed for a range of rare gastrointestinal diseases where GLP-2 can play a central role in addressing disease pathophysiology, including short bowel syndrome with intestinal failure (SBS-IF) and Acute Graft-Versus-Host Disease (aGVHD). About LINZESS LINZESS® is the #1 prescribed brand in the U.S. for the treatment of adult patients with irritable bowel syndrome with constipation (“IBS-C”) or chronic idiopathic constipation (“CIC”), based on IQVIA data. LINZESS is a once-daily capsule that helps relieve the abdominal pain, constipation, and overall abdominal symptoms of bloating, discomfort and pain associated with IBS-C, as well as the constipation, infrequent stools, hard stools, straining, and incomplete evacuation associated with CIC. LINZESS relieves constipation in children and adolescents aged 6 to 17 years with functional constipation. The recommended dose is 290 mcg for IBS-C patients and 145 mcg for CIC patients, with a 72 mcg dose approved for use in CIC depending on individual patient presentation or tolerability. In children with functional constipation aged 6 to 17 years, the recommended dose is 72 mcg. LINZESS is not a laxative; it is the first medicine approved by the FDA in a class called GC-C agonists. LINZESS contains a peptide called linaclotide that activates the GC-C receptor in the intestine. Activation of GC-C is thought to result in increased intestinal fluid secretion and accelerated transit and a decrease in the activity of pain-sensing nerves in the intestine. The clinical relevance of the effect on pain fibers, which is based on nonclinical studies, has not been established. In the United States , Ironwood and AbbVie co-develop and co-commercialize LINZESS for the treatment of adults with IBS-C or CIC. In Europe , AbbVie markets linaclotide under the brand name CONSTELLA ® for the treatment of adults with moderate to severe IBS-C. In Japan , Ironwood's partner, Astellas, markets linaclotide under the brand name LINZESS for the treatment of adults with IBS-C or CIC. Ironwood also has partnered with AstraZeneca for development and commercialization of LINZESS in China , and with AbbVie for development and commercialization of linaclotide in all other territories worldwide. LINZESS Important Safety Information INDICATIONS AND USAGE LINZESS® (linaclotide) is indicated for the treatment of both irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) in adults and functional constipation (FC) in children and adolescents 6 to 17 years of age. It is not known if LINZESS is safe and effective in children with FC less than 6 years of age or in children with IBS-C less than 18 years of age. IMPORTANT SAFETY INFORMATION WARNING: RISK OF SERIOUS DEHYDRATION IN PEDIATRIC PATIENTS LESS THAN 2 YEARS OF AGE LINZESS is contraindicated in patients less than 2 years of age. In nonclinical studies in neonatal mice, administration of a single, clinically relevant adult oral dose of linaclotide caused deaths due to dehydration. Contraindications LINZESS is contraindicated in patients less than 2 years of age due to the risk of serious dehydration. LINZESS is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction. Warnings and Precautions LINZESS is contraindicated in patients less than 2 years of age. In neonatal mice, linaclotide increased fluid secretion as a consequence of age-dependent elevated guanylate cyclase (GC-C) agonism, which was associated with increased mortality within the first 24 hours due to dehydration. There was no age dependent trend in GC-C intestinal expression in a clinical study of children 2 to less than 18 years of age; however, there are insufficient data available on GC-C intestinal expression in children less than 2 years of age to assess the risk of developing diarrhea and its potentially serious consequences in these patients. Diarrhea In adults, diarrhea was the most common adverse reaction in LINZESS-treated patients in the pooled IBS-C and CIC double-blind placebo-controlled trials. The incidence of diarrhea was similar in the IBS-C and CIC populations. Severe diarrhea was reported in 2% of 145 mcg and 290 mcg LINZESS-treated patients and in

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