Cadonilimab for PD-1/PD-L1 Blockade-refractory, MSI-H/dMMR, Advanced Colorectal Cancer

Cadonilimab (bispecific Anti-PD-1/CTLA-4 Antibody) for PD-1/PD-L1 Blockade-refractory, Microsatellite Instability-high (MSI-H) or Mismatch Repair-deficient (dMMR), Advanced Colorectal Cancer: a Single Group, Multicenter, Phase 2 Trial

Cadonilimab for PD-1/PD-L1 Blockade-refractory, MSI-H/dMMR, Advanced Colorectal Cancer (NCT05426005) is a Phase 1 / Phase 2 interventional studying Colorectal Cancer Stage IV and Mismatch Repair-deficient (dMMR), sponsored by Sun Yat-sen University. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

KEYNOTE-177 is currently the only randomized controlled phase III clinical trial evaluating the efficacy and safety of pembrolizumab versus standard chemotherapy combined with targeted first-line therapy for dMMR/MSI-H metastatic colorectal cancer. The study was conducted at 192 centers in 23 countries and enrolled a total of 307 subjects. The results of the study showed that the median PFS of pembrolizumab was 16.5 months, which was double the 8.2 months in the chemotherapy group (HR 0.60; 95% CI: 0.45-0.80; P = 0.0002). In addition, the ORR was 45.1% in the pembrolizumab group and 33.1% in the chemotherapy group, and a higher percentage of patients achieving a complete remission (CR) with pembrolizumab than in the chemotherapy group (13.1% vs. 3.9%). The U.S. FDA approved pembrolizumab in June 2020 for the first-line treatment of MSI-H/dMMR metastatic colorectal cancer. The results of the KEYNOTE-177 study showed that 29% of patients with dMMR/MSI-H metastatic colorectal cancer experienced direct disease progression (PD) after first-line pembrolizumab monotherapy. This may suggest that some dMMR/MSI-H patients have primary resistance to anti-PD-1 monotherapy. In the first-line treatment cohort of the CheckMate 142 study using nivolumab combined with ipilimumab, the proportion of patients with direct PD was 13%, suggesting that the combination of PD-1 inhibitors and anti-CTLA-4 mAb may have help overcome this primary resistance. In addition, in the second-line and above cohort of the CheckMate142 study, 12% of patients receiving nivolumab in combination with ipilimumab experienced PD directly, compared with 26% of patients receiving nivolumab alone. A study published on 《The Lancet Oncolog》 on the efficacy and safety of ipilimumab monotherapy and ipilimumab combined with anti-PD-1 monoclonal antibody in patients with anti-PD-1 monoclonal antibody-resistant melanoma Retrospective study. The study included 355 patients with unresectable metastatic stage III or IV melanoma who received ipilimumab monotherapy after failure of anti-PD-(L)1 monoclonal antibody (n=162), or Ipilimumab combined with anti-PD-1 therapy (n=193). The ORR was 31% in the combination arm, significantly higher than the 13% in the ipilimumab monotherapy arm. In addition, the median OS and PFS of the combination therapy group were 20.4 months and 3.0 months, respectively, which were also significantly higher than those of the single-agent group of 8.8 months and 2.6 months. The aim of this study was to evaluate the objective response rate (ORR) of Cadonilimab, a bispecific anti-PD-1/CTLA-4 antibody, for PD-1/PD-L1 blockade-refractory, microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR), advanced colorectal cancer.

What Stage of Research Is This?

Phase 1 trials test a new treatment for the first time in humans, focusing on safety, dosing, and how the body processes the drug. For Colorectal Cancer Stage IV, a Phase 1 study typically enrolls a small number of participants — often healthy volunteers or patients who have exhausted standard treatment options. Phase 1 results determine whether a treatment moves into larger Phase 2 efficacy studies.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 28 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: 1. Willing and able to provide written willing to sign a consent form. 2. Histological or cytological documentation of adenocarcinoma of the colon or rectum. 3. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1. 4. Tumor tissues were identified as mismatch repair-deficient (dMMR) by immunohistochemistry (IHC) method or microsatellite instability-high (MSI-H) by polymerase chain reaction (PCR). 5. Subjects with stage IV colorectal cancer must have measurable or non measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria, version 1.1. 6. Previous treatment with an anti-PD-1 or PD-L1 monoclonal antibody for advanced or metastatic colorectal cancer has failed. Treatment failure was defined as: disease progression or unacceptable toxicity during treatment or within 6 months after the last treatment. 7. Adequate bone marrow, liver and renal function as assessed by the laboratory required by protocol. Who Should NOT Join This Trial: 1. Previously received anti-cytotoxic T lymphocyte-associated antigen 4 (cytotoxic T-lymphocyte-associated Protein 4, CTLA-4) antibody. 2. Significant cardiovascular disease including unstable angina or myocardial infarction within 6 months before initiating study treatment. 3. Heart failure grade III/IV (NYHA-classification). 4. Unresolved toxicity higher than CTCAE v.5.0 Grade 1 attributed to any prior therapy/procedure. 5. Subjects with known allergy to the study drugs or to any of its excipients. 6. Current or recent (within 4 weeks prior to starting study treatment) treatment of another investigational drug or participation in another investigational study. 7. Breast- feeding or pregnant women. 8. Lack of effective contraception. Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

Inclusion Criteria: 1. Willing and able to provide written informed consent. 2. Histological or cytological documentation of adenocarcinoma of the colon or rectum. 3. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1. 4. Tumor tissues were identified as mismatch repair-deficient (dMMR) by immunohistochemistry (IHC) method or microsatellite instability-high (MSI-H) by polymerase chain reaction (PCR). 5. Subjects with stage IV colorectal cancer must have measurable or non measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria, version 1.1. 6. Previous treatment with an anti-PD-1 or PD-L1 monoclonal antibody for advanced or metastatic colorectal cancer has failed. Treatment failure was defined as: disease progression or unacceptable toxicity during treatment or within 6 months after the last treatment. 7. Adequate bone marrow, liver and renal function as assessed by the laboratory required by protocol. Exclusion Criteria: 1. Previously received anti-cytotoxic T lymphocyte-associated antigen 4 (cytotoxic T-lymphocyte-associated Protein 4, CTLA-4) antibody. 2. Significant cardiovascular disease including unstable angina or myocardial infarction within 6 months before initiating study treatment. 3. Heart failure grade III/IV (NYHA-classification). 4. Unresolved toxicity higher than CTCAE v.5.0 Grade 1 attributed to any prior therapy/procedure. 5. Subjects with known allergy to the study drugs or to any of its excipients. 6. Current or recent (within 4 weeks prior to starting study treatment) treatment of another investigational drug or participation in another investigational study. 7. Breast- feeding or pregnant women. 8. Lack of effective contraception.

Treatments Being Tested

DRUG

Cadonilimab

Cadonilimab, 6 mg/kg every 2 weeks until disease progression, intolerable toxicity, or duration of treatment for 2 years

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

The Sixth Affiliated Hospital of Sun Yat-sen University

Guangzhou, Guangdong, China

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT05426005), the sponsor (Sun Yat-sen University), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT05426005 clinical trial studying?

Who can participate in NCT05426005?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT05426005?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT05426005. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT05426005. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.