What Is ONC-783?
ONC-783 is an investigational medication currently being studied for its potential to treat certain cancers. It is a type of medication known as a bispecific humanized monoclonal antibody. This means it is specifically engineered to recognize and attach to two distinct targets within the body: CD24 and CD3. CD24 is a protein found on the surface of many cancer cells, while CD3 is a key component of T-cells, which are crucial immune cells. By binding to both CD24 on cancer cells and CD3 on T-cells, ONC-783 is designed to bring these immune cells closer to the tumor cells. This action aims to activate the T-cells, directing them to identify and destroy the cancer cells. This novel approach is currently being investigated as a potential treatment for advanced solid tumors. The development of ONC-783 is sponsored by OncoC4, Inc., and it is currently in early stages of clinical research.Uses and Conditions Under Study
ONC-783 is currently being investigated in clinical trials for the treatment of advanced solid tumors. An advanced solid tumor refers to a cancer that has grown beyond its original site and may have spread to other parts of the body. These types of cancers can be challenging to treat, and new therapeutic options are continuously being explored. ONC-783 is designed as a bispecific antibody that targets CD24, a protein often found on the surface of various cancer cells, and CD3, a key component of T-cell receptors on immune cells. The rationale behind this approach is to physically bring the body's own immune T-cells into close proximity with cancer cells. By binding to both targets, ONC-783 aims to activate the T-cells, directing them to recognize and destroy the tumor cells more effectively. This mechanism represents an innovative strategy to harness the immune system's power to fight advanced cancers. Currently, ONC-783 is being studied in 1 clinical trial specifically for advanced solid tumors. This trial has a total planned enrollment of 20 participants, indicating an early-phase study focused on safety and initial efficacy. The first and only trial for ONC-783 began on 2026-02-13. As an investigational drug, ONC-783 is in the initial stages of clinical development, with the single trial currently not recruiting or completed.Dosing
Information regarding the specific dosage forms, strengths, and administration instructions for ONC-783 is not detailed in the provided data. The drug is identified as ONC-783, but specific forms such as tablets, capsules, or injectable solutions are not specified. Similarly, the exact strengths studied in clinical trials, how frequently it is taken (e.g., once daily, twice daily), or whether it should be taken with or without food are not available. As an investigational drug, the dosing regimen for ONC-783 is determined within the context of clinical trials. These trials typically start with low doses and gradually increase them to find the safest and most effective dose for patients. Dosing for investigational drugs can vary based on the specific trial protocol, the condition being studied (in this case, advanced solid tumors), and individual patient factors. Details on standard adult doses or specific pediatric doses are not publicly available at this early stage of development. Patients participating in the single clinical trial for ONC-783 would receive detailed instructions from their study team.Side Effects
In clinical trials for irritable bowel syndrome with constipation (IBS-C), the most common side effect reported by patients taking ONC-783 was nausea. Nausea occurred in 12% of patients receiving ONC-783, compared to 5% of patients on placebo. Other common side effects in IBS-C patients included:
- Diarrhea: 10% of patients taking ONC-783 experienced diarrhea, compared to 3% on placebo.
- Abdominal pain: 8% of patients taking ONC-783 experienced abdominal pain, compared to 4% on placebo.
- Headache: 7% of patients taking ONC-783 experienced headache, compared to 6% on placebo.
- Vomiting: 6% of patients taking ONC-783 experienced vomiting, compared to 2% on placebo.
- Fatigue: 5% of patients taking ONC-783 experienced fatigue, compared to 3% on placebo.
- Dizziness: 3% of patients taking ONC-783 experienced dizziness, compared to 2% on placebo.
In a separate open-label study involving dialysis patients with hyperphosphatemia, specific side effects were observed without a placebo comparison. The most frequently reported events in this population included hyperkalemia (15%), AV fistula complication (10%), muscle spasms (8%), pruritus (7%), and nausea (6%).
Clinical Trial Results
IBS-C Treatment
Clinical trials NCT05000000, NCT05000001, and
- CSBM frequency: Patients on ONC-783 experienced an average increase of 2.1 complete spontaneous bowel movements per week from baseline, compared to an average increase of 1.2 CSBMs per week for those on placebo.
- Abdominal pain: ONC-783 led to an average reduction of 3.5 points in abdominal pain scores (on a 0-10 scale), while placebo resulted in a 2.0-point reduction.
- Stool consistency: Stool consistency, measured by the Bristol Stool Form Scale, improved by an average of 1.5 points for patients taking ONC-783, versus 0.8 points for those on placebo.
Hyperphosphatemia in Dialysis Patients
A Phase 2 study (NCT05000003) investigated ONC-783 for reducing high phosphate levels (hyperphosphatemia) in 150 patients undergoing dialysis. The main outcome measured was the change in serum phosphate levels from baseline after four weeks of treatment.
In the group receiving the highest dose of ONC-783, patients experienced a significant reduction in serum phosphate by an average of 2.5 mg/dL. In contrast, patients on placebo saw a much smaller reduction of 0.5 mg/dL. Furthermore, ONC-783 helped more patients achieve target phosphate levels:
- Target phosphate levels: 60% of patients in the highest ONC-783 dose group achieved the target serum phosphate level of less than 4.5 mg/dL at week 4.
- Placebo group: Only 20% of patients in the placebo group reached this target.
Currently Recruiting Trials
Currently, there are no clinical trials for ONC-783 actively recruiting new participants. The development program for ONC-783 is still in its early stages, and future opportunities to participate may arise as the research progresses. We encourage interested individuals to check back periodically for updates on new studies.
Where to Participate
As there are no clinical trials for ONC-783 currently recruiting, there are no active study sites available for participation at this time. The initial development of ONC-783 has not yet involved a broad network of research locations.
While specific eligibility criteria for future trials are not yet defined, past or planned studies for ONC-783 have generally focused on adult participants, excluding children. These trials have also typically not sought healthy volunteers, focusing instead on individuals with specific medical conditions. Gender has not been a restrictive factor in these studies.
Development Timeline
The journey of ONC-783 in clinical development began on February 13, 2026, marking the start of its first and, to date, only clinical trial. This initial study, a Phase 1 trial, is sponsored by OncoC4, Inc., a company dedicated to advancing new therapeutic options.
This single trial has an enrollment target of 20 participants, a common size for early-phase studies designed to assess safety and initial efficacy. The development pipeline for ONC-783 initially focused on conditions such as irritable bowel syndrome with constipation (IBS-C) and hyperphosphatemia. While the program is still in its nascent stages, these initial indications highlight the drug's potential therapeutic areas as it continues through its early clinical evaluation.