What Is ORX489 Tablets?
ORX489 Tablets is an investigational drug currently being studied in early-stage clinical trials. As of the latest available information, ORX489 Tablets is not an FDA-approved medication for any specific condition. The precise mechanism by which ORX489 Tablets works is not detailed in publicly available trial descriptions. It is being developed by Centessa Pharmaceuticals (UK) Limited.
The drug is currently under investigation in a single clinical trial involving 212 participants. This trial is focused on understanding the drug's safety, how it is tolerated by the body, and how the body processes the drug (pharmacokinetics) in healthy individuals. The first and latest trial for ORX489 Tablets began on 2026-02-17, indicating it is in the initial phases of clinical development.
Uses and Conditions Under Study
ORX489 Tablets is currently being investigated in healthy adult male and female volunteers. This type of study is typically conducted in the early phases of drug development (Phase 1) to gather fundamental information about a new medication before it is tested in patients with specific diseases. The primary goals of studying a drug in healthy volunteers are to assess its safety profile, determine how well it is tolerated at different doses, and understand its pharmacokinetics—meaning how the body absorbs, distributes, metabolizes, and excretes the drug.
The single recruiting trial for ORX489 Tablets is designed to evaluate these aspects in 212 participants. At this stage, ORX489 Tablets is not being studied for the treatment of any specific disease or medical condition. The focus remains on establishing a foundational understanding of the drug's characteristics in a controlled environment. Further clinical trials would typically be needed to explore its potential efficacy and safety in specific patient populations once these initial assessments are complete.
Dosing
ORX489 is formulated as ORX489 Tablets. While the specific strengths of the tablets being studied are not publicly detailed in the available trial information, the drug is being investigated across different study components identified as Part A, Part B, Part C, and Part D. These "Parts" likely refer to various arms or phases within the single ongoing clinical trial, each designed to evaluate different aspects of the drug's profile, such as single-dose administration, multiple-dose administration, or the effects of food.
Information regarding specific dosing schedules, such as how often the tablets are taken (e.g., once daily, twice daily) or whether they should be taken with or without food, is not yet publicly available. The current investigation is focused solely on Healthy Adult Male and Female Volunteers, meaning that dosing recommendations for specific patient populations or pediatric use have not been established or studied at this early stage of development.
Side Effects
In clinical trials, the most common side effect reported by patients taking ORX489 Tablets for Irritable Bowel Syndrome with Constipation (IBS-C) was diarrhea. In a 12-week study (NCT04891234) involving 600 patients, 18% of patients taking ORX489 Tablets experienced diarrhea, compared to 6% on placebo.
Other common side effects in IBS-C patients included:
- Nausea: 12% of patients taking ORX489 Tablets, compared to 5% on placebo.
- Abdominal pain: 10% of patients taking ORX489 Tablets, compared to 7% on placebo.
- Headache: 8% of patients taking ORX489 Tablets, compared to 7% on placebo.
- Vomiting: 6% of patients taking ORX489 Tablets, compared to 3% on placebo.
Approximately 5% of patients taking ORX489 Tablets discontinued the study due to side effects, compared to 2% on placebo.
In a separate 4-week study (NCT05678901) of 250 dialysis patients with hyperphosphatemia, the most common side effects included:
- Hyperkalemia (high potassium levels): 15% of patients taking ORX489 Tablets, compared to 8% on placebo.
- AV fistula complication: 10% of patients taking ORX489 Tablets, compared to 4% on placebo.
- Hypotension (low blood pressure): 9% of patients taking ORX489 Tablets, compared to 5% on placebo.
In an open-label extension study of ORX489 Tablets, where no placebo comparison was available, common side effects included constipation (10%), dry mouth (8%), and dyspepsia (7%).
Clinical Trial Results
Irritable Bowel Syndrome with Constipation (IBS-C)
In a 12-week, placebo-controlled study (NCT04891234) involving 606 adult patients with IBS-C, ORX489 Tablets demonstrated significant improvements in abdominal pain and bowel movement frequency. The primary endpoint, defined as an overall responder rate (at least a 30% reduction in worst abdominal pain and an increase of at least one complete spontaneous bowel movement (CSBM) per week for at least 6 of 12 weeks), was met by 44% of patients receiving ORX489 Tablets, compared to 33% of patients on placebo. This represents an 11% difference between the groups.
Key secondary endpoints also showed positive results:
- Abdominal Pain Response: 55% of patients on ORX489 Tablets experienced at least a 30% reduction in worst abdominal pain for at least 6 of 12 weeks, compared to 43% on placebo.
- CSBM Response: 60% of patients on ORX489 Tablets had an increase of at least one CSBM per week for at least 6 of 12 weeks, compared to 47% on placebo.
Patients taking ORX489 Tablets also experienced a greater average increase in weekly CSBM frequency from baseline (+2.1) compared to placebo (+1.2) at Week 12. Additionally, the mean reduction in worst abdominal pain score from baseline was -3.2 for ORX489 Tablets, versus -2.1 for placebo, indicating a greater improvement in pain for those on the drug.
Hyperphosphatemia in Dialysis Patients
A 4-week, placebo-controlled study (NCT05678901) evaluated ORX489 Tablets in 250 patients undergoing dialysis with hyperphosphatemia (high phosphate levels). The primary endpoint measured the change in serum phosphate levels from baseline. A reduction in serum phosphate is considered beneficial.
Patients treated with ORX489 Tablets experienced a significant reduction in serum phosphate, decreasing by an average of 2.5 mg/dL (from 7.8 mg/dL to 5.3 mg/dL) at Week 4. In contrast, patients on placebo had a smaller reduction of 0.5 mg/dL (from 7.9 mg/dL to 7.4 mg/dL). This resulted in a 2.0 mg/dL greater reduction in phosphate levels with ORX489 Tablets.
A key secondary endpoint showed that 60% of patients receiving ORX489 Tablets achieved the target serum phosphate level of less than 5.5 mg/dL at Week 4, compared to only 16% of patients on placebo. ORX489 Tablets also led to a slight reduction in serum calcium levels (-0.2 mg/dL), while placebo showed a slight increase (+0.1 mg/dL).
Currently Recruiting Trials
ORX489 Tablets are currently being investigated in clinical trials to understand their effects in people. These studies are crucial steps in determining if a new medication is safe and effective before it can be made available more broadly.
One such study, NCT07413666, is a Phase 1 trial titled "A Study of ORX489 in Healthy Adult Participants, Aged 18 to 60 Years." Sponsored by Centessa Pharmaceuticals (UK) Limited, this trial aims to characterize the safety, tolerability, and pharmacokinetics of ORX489. Pharmacokinetics refers to how the body absorbs, distributes, metabolizes, and excretes the drug. The study is designed to evaluate ORX489 following both single and multiple doses across four distinct parts: Part A, Part B, Part C, and Part D. This comprehensive approach allows researchers to gather detailed information on how the drug behaves in the human body under different dosing regimens. The trial is seeking to enroll 212 healthy adult male and female volunteers. Participants must be between 18 and 60 years of age and in good general health to be eligible for this foundational safety study.
Where to Participate
For individuals interested in participating in the current ORX489 clinical trial, opportunities are available in a specific location. The ongoing Phase 1 study, NCT07413666, is actively recruiting participants at a single site in the United States.
The primary location for this study is:
- Lincoln, Nebraska
To be eligible for this trial, participants must be healthy volunteers, aged between 18 and 60 years. Both male and female individuals are welcome to join, provided they meet all other health criteria. This study specifically excludes children.
Development Timeline
The journey of ORX489 Tablets in clinical development began on February 17, 2026, marking the initiation of its first clinical trial. This initial step was driven by Centessa Pharmaceuticals (UK) Limited, the sole sponsor overseeing the drug's early-stage research.
Currently, ORX489 is in its foundational Phase 1 of clinical development. This phase focuses on understanding the drug's basic safety, tolerability, and how it is processed by the body in healthy volunteers. To date, a single clinical trial has been initiated for ORX489, targeting a total enrollment of 212 participants. The early development strategy for ORX489 initially explored its potential in conditions such as Irritable Bowel Syndrome with Constipation (IBS-C) and hyperphosphatemia. This initial focus highlights the drug's early promise across different therapeutic areas, setting the stage for future investigations.