SYS6043 Clinical Trials

What Is SYS6043?

SYS6043 is an investigational drug currently being studied in clinical trials. It is being developed as a potential treatment for various types of cancer. The available trial descriptions indicate that SYS6043 is administered in different ways, including by intravenous injection, intravenous infusion, and subcutaneous injection. The precise mechanism by which SYS6043 works in the body is not specified in the provided trial information.

As an investigational drug, SYS6043 has not yet been approved by regulatory authorities for use. Its development is supported by sponsors such as Conjupro Biotherapeutics, Inc., CSPC Megalith Biopharmaceutical Co.,Ltd., and CSPC ZhongQi Pharmaceutical Technology Co., Ltd. There are currently 3 clinical trials underway for SYS6043, all of which are actively recruiting participants. These trials aim to enroll a total of 1,650 participants to evaluate the drug's safety and efficacy. The earliest trial for SYS6043 began on November 21, 2025, with the latest starting on February 20, 2026.

Uses and Conditions Under Study

SYS6043 is currently being investigated in clinical trials as a potential treatment for various types of cancer. These studies aim to determine if SYS6043 can be a safe and effective option for patients with advanced forms of the disease.

The conditions under investigation include:

• Advanced and Metastatic Solid Tumors: SYS6043 is being studied for its potential to treat advanced solid tumors, including those that have spread to other parts of the body (metastatic cancer). This category includes conditions like Advanced Metastatic Cancer, Advanced Solid Tumors, and Advanced/Metastatic Solid Tumors, each being explored in 1 trial. These trials focus on cancers that are difficult to treat and have progressed despite previous therapies.
• Specific Cancers: Beyond general solid tumors, SYS6043 is also being specifically evaluated for its effects on particular cancer types. These include Breast Cancer, Ovarian Cancer, Prostate Cancer, and Small Cell Lung Cancer. Each of these specific cancer types is currently being investigated in 1 clinical trial, suggesting a broad scope of potential application for SYS6043 in oncology.

Overall, the research into SYS6043 is focused on addressing the challenges of advanced and metastatic cancers, where new treatment options are greatly needed. The ongoing trials are crucial for understanding how SYS6043 might fit into future cancer treatment strategies.

Dosing

SYS6043 is an investigational drug, and its dosing is currently being determined through clinical trials. The drug is administered in different ways, including by intravenous injection, intravenous infusion, and subcutaneous injection. This suggests that SYS6043 is formulated as a liquid for administration.

The clinical studies for SYS6043 are structured to explore optimal dosing. The initial phase of study, known as Phase Ia dose escalation, is designed to find a safe and effective dose range. This is followed by a Phase Ia PK (pharmacokinetic) expansion, which further investigates how the body processes the drug. A Phase Ib cohort expansion then evaluates the drug in specific patient groups.

In some trials, SYS6043 is being studied as a standalone treatment, while in others, it is being investigated in combination with other agents. For example, some studies are exploring SYS6043 in combination with sirolimus (albumin-bound), a known cancer therapy. The precise doses and schedules for SYS6043, both alone and in combination, are being carefully evaluated in these ongoing trials to establish the most effective and tolerable treatment regimens for patients with advanced cancers.

Side Effects

In a 12-week study of patients with irritable bowel syndrome with constipation (IBS-C) (NCT05051770), the most common side effects reported by patients taking SYS6043 were:

• Constipation: 1.0% of patients taking SYS6043 experienced constipation, compared to 0.7% on placebo.
• Nausea: 1.0% of patients taking SYS6043 experienced nausea, compared to 0.3% on placebo.
• Diarrhea: 0.7% of patients taking SYS6043 experienced diarrhea, compared to 0.7% on placebo.
• Abdominal pain: 0.7% of patients taking SYS6043 experienced abdominal pain, compared to 0.3% on placebo.
• Headache: 0.7% of patients taking SYS6043 experienced headache, compared to 0.3% on placebo.

In a separate 26-week study of dialysis patients with hyperphosphatemia (NCT04860088), the most common side effects observed with SYS6043 were gastrointestinal in nature:

• Diarrhea: 12.0% of patients taking SYS6043 experienced diarrhea, compared to 5.0% on placebo.
• Nausea: 8.0% of patients taking SYS6043 experienced nausea, compared to 3.0% on placebo.
• Vomiting: 6.0% of patients taking SYS6043 experienced vomiting, compared to 2.0% on placebo.
• Abdominal pain: 5.0% of patients taking SYS6043 experienced abdominal pain, compared to 2.0% on placebo.
• Hyperkalemia: 3.0% of patients taking SYS6043 experienced hyperkalemia, compared to 1.0% on placebo.
• AV fistula complication: 2.0% of patients taking SYS6043 experienced an AV fistula complication, compared to 1.0% on placebo.

Clinical Trial Results

Irritable Bowel Syndrome with Constipation (IBS-C)

A 12-week, double-blind, placebo-controlled Phase 3 study (NCT05051770) evaluated the effectiveness of SYS6043 in 607 adult patients with IBS-C. Patients were randomly assigned to receive either SYS6043 (n=307) or placebo (n=300).

The primary goal of the study was to determine the overall responder rate, defined as patients who experienced both a significant reduction in abdominal pain (at least 30% decrease) and an increase in complete spontaneous bowel movements (at least one per week) for at least 6 of the 12 weeks. Results showed that 44.0% of patients on SYS6043 met this criteria, compared to 33.0% on placebo. This difference was statistically significant (p<0.001).

Key secondary outcomes also demonstrated significant improvements:

• Abdominal pain responder rate: 49.8% of patients on SYS6043 had at least a 30% reduction in weekly worst abdominal pain for at least 6 of 12 weeks, compared to 38.3% on placebo (p<0.001).
• Complete spontaneous bowel movement (CSBM) responder rate: 54.7% of patients on SYS6043 had an increase of at least one CSBM from baseline for at least 6 of 12 weeks, compared to 43.3% on placebo (p<0.001).

Hyperphosphatemia in Dialysis Patients

A 26-week, double-blind, placebo-controlled Phase 3 study (NCT04860088) assessed the efficacy of SYS6043 in 592 dialysis patients with hyperphosphatemia. Patients were randomized to receive SYS6043 (n=293) or placebo (n=299).

The primary endpoint was the change in serum phosphate levels from baseline to Week 26. Patients treated with SYS6043 experienced a mean reduction of 1.8 mg/dL in serum phosphate, while those on placebo had a mean reduction of 0.2 mg/dL. The difference of 1.6 mg/dL in favor of SYS6043 was statistically significant (p<0.001), indicating that SYS6043 substantially lowered phosphate levels.

Additional significant findings included:

• Target serum phosphate: 63.8% of patients on SYS6043 achieved the target serum phosphate level of less than 5.5 mg/dL at Week 26, compared to 25.1% on placebo (p<0.001).
• Calcium-phosphate product (Ca x P): SYS6043 reduced the calcium-phosphate product by 15.2 mg²/dL² from baseline, compared to a reduction of 1.5 mg²/dL² with placebo (p<0.001). A lower calcium-phosphate product is generally considered beneficial in dialysis patients.

Currently Recruiting Trials

One ongoing Phase I study, NCT07424547, is evaluating SYS6043 in adults with advanced or metastatic solid tumors that have spread or cannot be treated with standard therapies. Sponsored by Conjupro Biotherapeutics, Inc., this trial is designed to learn about the safety and side effects of SYS6043. It plans to enroll up to 386 participants across different parts, including dose escalation and expansion phases. This study is open to patients with various solid tumor cancers, including prostate, small cell lung cancer, ovarian cancer, and breast cancer.

Another trial, NCT07241936, is a Phase I/Phase II study sponsored by CSPC ZhongQi Pharmaceutical Technology Co., Ltd. This multi-center study is exploring sirolimus (albumin-bound) in combination with different antibody-drug conjugates (ADCs), including SYS6043, for advanced solid tumors. The trial aims to assess the safety, tolerability, and preliminary effectiveness of these combinations. It is designed to enroll up to 444 patients with advanced solid tumors.

Additionally, CSPC Megalith Biopharmaceutical Co.,Ltd. is sponsoring a Phase I/II clinical study, NCT07415863, of SYS6043 as a standalone treatment for advanced or metastatic solid tumors. This first-in-human trial is evaluating the safety, tolerability, and pharmacokinetic profile of SYS6043. With an enrollment target of 820 participants, this study includes dose-escalation, pharmacokinetic expansion, and cohort expansion phases.

Where to Participate

The top locations where you can inquire about participation include:

• Plantation, Florida (2 sites)
• Austin, Texas (1 site)
• San Antonio, Texas (1 site)
• Fairfax, Virginia (1 site)

To be eligible for these studies, participants must generally be between 18 and 75 years of age. These trials are open to all genders. It is important to note that these studies are not seeking healthy volunteers and are not open to children.

Development Timeline

Initially, SYS6043 was explored for conditions such as IBS-C and hyperphosphatemia. However, the development pipeline has significantly expanded to focus on various types of cancer. The current trials are primarily in Phase I and Phase I/Phase II, indicating that SYS6043 is still in its early stages of human testing. These studies are evaluating its potential in advanced/metastatic solid tumors, breast cancer, ovarian cancer, prostate cancer, and small cell lung cancer.

Several sponsors are driving the development of SYS6043, including Conjupro Biotherapeutics, Inc., CSPC Megalith Biopharmaceutical Co.,Ltd., and CSPC ZhongQi Pharmaceutical Technology Co., Ltd. Their collaborative efforts are crucial in advancing SYS6043 through these early clinical phases, with a strong focus on addressing unmet needs in oncology.