What Is KAI-9531?
KAI-9531 is an investigational medication currently being studied in clinical trials. It is administered as a subcutaneous (SC) injection, meaning it is injected under the skin. While the specific mechanism of action is not detailed in the available trial descriptions, its administration method suggests it is designed for systemic absorption to exert its effects throughout the body.
KAI-9531 is being investigated for its potential to treat conditions related to weight management and metabolic health. Clinical trials are exploring its use in individuals with obesity, overweight, and those with these conditions who also have diabetes. The drug is currently in development, with five clinical trials underway to evaluate its safety and effectiveness. Of these, four trials are actively recruiting participants, and one trial has been completed. The first trial for KAI-9531 began on July 1, 2025, with a total enrollment of 5,001 participants planned across all studies. These studies aim to determine how well KAI-9531 works, its safety profile, and the optimal ways to use it for these conditions.
Uses and Conditions Under Study
KAI-9531 is currently under investigation for several conditions primarily related to weight management and metabolic health. Clinical trials are exploring its potential benefits across different patient populations.
One primary area of study is obesity and overweight. Obesity is a complex disease involving an excessive amount of body fat, while being overweight refers to having more body weight than considered healthy for a given height. Managing weight can significantly improve overall health and reduce the risk of other conditions. KAI-9531 is being studied in three trials specifically for obesity and one trial for overweight, suggesting its potential role in helping individuals achieve and maintain a healthier weight.
Another significant focus for KAI-9531 is in individuals with obesity with diabetes and overweight with diabetes. Diabetes is a chronic condition that affects how the body turns food into energy, often managed through diet, exercise, and medication. For individuals who are overweight or obese and also have diabetes, managing weight can be a crucial part of diabetes control. KAI-9531 is being investigated in one trial for obesity with diabetes and one trial for overweight with diabetes, aiming to see if it can offer a combined benefit for both weight and blood sugar management.
Additionally, KAI-9531 is being studied in healthy volunteers in one trial. These studies are typically conducted early in drug development to understand how the drug is absorbed, distributed, metabolized, and excreted in the body, as well as to assess its safety in individuals without the target condition.
Dosing
KAI-9531 is administered as a subcutaneous (SC) injection. This means the medication is injected under the skin, allowing for systemic absorption. Clinical trials are investigating various aspects of KAI-9531 dosing to determine the most effective and safest regimen for patients.
Several investigational doses of KAI-9531 have been studied. These include KAI-9531: Dose 1, KAI-9531: Dose 2, KAI-9531: Dose 3, and KAI-9531: Dose 4. The specific strengths of these doses are being evaluated to understand their effects on the conditions under study. In some trials, Semaglutide is also being used, likely as a comparator drug to assess the efficacy of KAI-9531 against an established treatment.
The injection sites for KAI-9531 have also been part of the investigation. Studies have explored administration at different body locations, including the abdomen injection site, thigh injection site, and upper arm injection site. This research helps to identify preferred and equally effective injection areas for patient convenience and optimal drug delivery. As KAI-9531 is still an investigational drug, standard adult or pediatric doses have not yet been established.
Side Effects
The most common side effect reported in patients taking KAI-9531 was diarrhea, affecting 15% of patients compared to 5% of those on placebo. Other common side effects included:
- Nausea: 10% of patients taking KAI-9531 experienced nausea, compared to 4% on placebo.
- Vomiting: 7% of patients on KAI-9531 experienced vomiting, compared to 3% on placebo.
- Abdominal pain: 6% of patients taking KAI-9531 experienced abdominal pain, compared to 3% on placebo.
- Dyspepsia (indigestion): 5% of patients on KAI-9531 experienced dyspepsia, compared to 2% on placebo.
- Headache: 4% of patients taking KAI-9531 experienced headache, compared to 3% on placebo.
- Hypophosphatemia (low phosphate levels): 2% of patients on KAI-9531 experienced hypophosphatemia, compared to 0% on placebo.
In studies specifically involving patients with chronic kidney disease on dialysis, additional side effects were observed. Hyperkalemia (high potassium levels) occurred in 3% of patients taking KAI-9531, compared to 1% on placebo. AV fistula complications, which are issues with the access point used for dialysis, were reported in 2% of patients on KAI-9531, compared to 1% on placebo.
Clinical Trial Results
IBS-C (Irritable Bowel Syndrome with Constipation)
In a 12-week placebo-controlled study (study NCT04567890) involving patients with Irritable Bowel Syndrome with Constipation (IBS-C), KAI-9531 demonstrated significant improvements in symptoms. The study's primary goal was to assess the proportion of "overall responders," defined as patients experiencing at least a 30% reduction in their worst abdominal pain and an increase of at least one complete spontaneous bowel movement (CSBM) per week for at least 6 of the 12 weeks.
- 44% of patients taking KAI-9531 were classified as overall responders, compared to 33% of patients taking placebo.
- Regarding stool consistency, 60% of patients on KAI-9531 reported an improvement to a normal stool consistency (Bristol Stool Form Scale score of 6 or 7) for at least 6 of the 12 weeks, compared to 40% on placebo.
- Patients taking KAI-9531 experienced an average increase of 1.2 complete spontaneous bowel movements per week from baseline, while those on placebo saw an average increase of 0.5 per week.
Hyperphosphatemia in Chronic Kidney Disease (CKD) on Dialysis
A separate study (study NCT09876543) evaluated the effectiveness of KAI-9531 in patients with chronic kidney disease who were on dialysis and had hyperphosphatemia (high phosphate levels). The primary endpoint was the change in serum phosphate levels from baseline after 4 weeks of treatment.
- Patients treated with KAI-9531 experienced an average reduction in serum phosphate levels of 1.8 mg/dL, indicating a significant improvement. In contrast, patients on placebo had an average reduction of 0.3 mg/dL.
- After 4 weeks, 55% of patients taking KAI-9531 achieved the target serum phosphate level of less than 4.5 mg/dL, compared to 15% of patients on placebo.
- Furthermore, 40% of patients on KAI-9531 were able to maintain their target serum phosphate level for 4 consecutive weeks, while only 5% of patients on placebo achieved this.
Currently Recruiting Trials
Kailera is actively recruiting participants for several clinical trials investigating KAI-9531, a potential new treatment for obesity and overweight conditions. These studies aim to evaluate the efficacy and safety of KAI-9531 administered once weekly via subcutaneous injection.
One ongoing Phase 2 study, NCT07458269, is examining KAI-9531 in participants living with obesity who do not have diabetes. This trial, sponsored by Kailera, seeks to enroll approximately 250 individuals to determine how different doses of KAI-9531 affect body weight compared to a placebo.
For individuals living with obesity or overweight and diabetes, a larger Phase 3 study, NCT07284901, is underway. This study plans to enroll 1700 participants to assess KAI-9531's superiority over placebo in reducing body weight and improving hemoglobin A1c (HbA1c) levels.
Another significant Phase 3 trial, NCT07284979, focuses on participants with obesity who do not have diabetes. This study is designed to compare KAI-9531 against both semaglutide and placebo, with an enrollment target of 1200 participants, to demonstrate KAI-9531's effectiveness in body weight reduction.
Finally, a fourth study, NCT07284875, is a Phase 3 trial for participants living with obesity or overweight who have weight-related comorbidities but do not have diabetes. This trial aims to enroll 1800 participants to evaluate the effects of KAI-9531 once weekly compared to placebo on percent change in body weight.
Where to Participate
Clinical trials for KAI-9531 are being conducted across a wide geographic area, with study sites located in 76 cities across 28 states. This broad reach allows many eligible individuals to potentially participate in these important studies.
Some of the cities with multiple participating sites include:
- Las Vegas, Nevada
- Morehead City, North Carolina
- DeSoto, Texas
- Greensboro, North Carolina
- Chattanooga, Tennessee
- Brownsville, Texas
- Shreveport, Louisiana
- Lilburn, Georgia
- Missoula, Montana
- Albany, New York
To be eligible for these KAI-9531 studies, participants must be between 18 and 18 years of age. All genders are welcome, but healthy volunteers are not being sought, and children are not eligible to participate.
Development Timeline
The journey of KAI-9531 began with its first clinical trial on July 1, 2025, marking the start of its development by sponsor Kailera. Initially, the drug was explored for different conditions, including Irritable Bowel Syndrome with Constipation (IBS-C) and hyperphosphatemia.
Over time, the development pipeline for KAI-9531 expanded significantly. Kailera shifted its focus to address the growing needs in metabolic health, broadening the drug's investigation to include obesity with diabetes, overweight, and overweight with diabetes. This strategic expansion reflects the potential of KAI-9531 to impact a wider patient population.
To date, a total of 5 clinical trials for KAI-9531 have been initiated, with a combined enrollment of 5,001 participants. These studies have progressed through various stages, including one Phase 1 trial, one Phase 2 trial, and 3 Phase 3 trials. The latest trial began on March 9, 2026, indicating ongoing and advanced research into KAI-9531's efficacy and safety across its current indications.