Neoadjuvant Pembrolizumab and Porustobart in Resectable pMMR/MSS Colon Cancer

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age18 Years to no maximum
• SexAll
• Healthy volunteersNo

You may be able to join if

• ≥18 years of age at consent
• Adenocarcinoma of the colon (rectosigmoid considered non-rectal); pMMR/MSS status
• Any T3 or T4, N any, M0; disease amenable to surgical resection
• ECOG Performance Status 0-1
• Adequate tumor tissue sample with associated pathology report
• Adequate hematologic, hepatic, and renal function
• Reproductive status/contraception requirements per protocol

You cannot join if

• Investigational agent within 3 weeks of first dose
• Imminent or urgent need for surgery
• Prior treatment with ICIs targeting CTLA-4, PD-1, or PD-L1
• Systemic corticosteroid/immunosuppressive therapy within 1 week of first dose (exceptions apply)
• History of severe hypersensitivity to a fully human mAb; interstitial lung disease; pneumonitis requiring corticosteroids
• Active or history of autoimmune disease requiring systemic treatment within 2 years
• Major surgery within 4 weeks of first dose; active infection requiring treatment

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

anti-CTLA4 monoclonal antibody HBM4003. A recombinant human heavy chain only antibody (HCAb) directed against the human T-cell-expressed receptor cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4;CTLA4), with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration, anti-CTLA-4 monoclonal antibody HBM4003 targets and binds to CTLA-4 expressed on T cells, and inhibits the CTLA-4-mediated downregulation of T-cell activation. This leads to a cytotoxic T-lymphocyte (CTL)-mediated immune response against cancer cells. In addition, HBM4003 induces an antibody-dependent cell cytotoxicity (ADCC). CTLA-4, an inhibitory receptor and member of the immunoglobulin superfamily (IgSF), plays a key role in the downregulation of the immune system. HBM4003, being a HCAb, is smaller than conventional antibodies which may allow for increased tissue penetration. NCI Drug Dictionary

pembrolizumab. A humanized monoclonal immunoglobulin (Ig) G4 antibody directed against human cell surface receptor PD-1 (programmed death-1 or programmed cell death-1) with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration, pembrolizumab binds to PD-1, an inhibitory signaling receptor expressed on the surface of activated T cells, and blocks the binding to and activation of PD-1 by its ligands, which results in the activation of T-cell-mediated immune responses against tumor cells. The ligands for PD-1 include programmed cell death ligand 1 (PD-L1), overexpressed on certain cancer cells, and programmed cell death ligand 2 (PD-L2), which is primarily expressed on APCs. Activated PD-1 negatively regulates T-cell activation and plays a key role in in tumor evasion from host immunity. NCI Drug Dictionary

Treatments listed in the registry

• Pembrolizumab (Drug): Administered to: Dose Schedule 1 - Porustobart + Pembrolizumab, Dose Schedule 2 - Porustobart + Pembrolizumab
• Porustobart (Drug): Administered to: Dose Schedule 1 - Porustobart + Pembrolizumab, Dose Schedule 2 - Porustobart + Pembrolizumab

Randomized · Parallel · masking: None

Main goals

• Major Pathologic Response (MPR) rate by Blinded Independent Pathologic Review (BIPR) (Assessed from surgical resection specimen (surgery occurs Day 42-Day 63, i.e., approximately Week 6-Week 9 after first dose))

Other goals

• Pathologic Complete Response (pCR) rate
• Incidence of treatment-related adverse events (AEs), serious adverse events (SAEs), and immune-related AEs

Planned enrollment: 100 (estimated).

• Investigator Site, Los Angeles, California
• Investigator Site, Cleveland, Ohio
• Investigator Site, Seattle, Washington

Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT07808151
• NCI Drug Dictionary: C173540
• NCI Drug Dictionary: C106432

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Oct 26, 2026. Public record; not medical advice.