CD66c-targeted CD40B adaptive transfer to enhance cytotoxic T cell responses in colorectal cancer
Abstract
BackgroundColorectal cancer (CRC), particularly microsatellite-stable (MSS) CRC, shows a limited response to immune checkpoint inhibitors (ICIs). Novel strategies are needed to enhance antigen-specific T cell immunity. CD66c (CEACAM6) is a tumour-associated antigen overexpressed in CRC and involved in immune evasion. CD40-activated B cells (CD40B) can function as effective antigen-presenting cells (APCs) in adoptive immunotherapy.MethodsWe screened a CD66c-derived peptide library using IFN-γ ELISpot assays in peripheral blood mononuclear cells (PBMCs) from patients with CRC and healthy controls to identify immunodominant epitopes. We isolated antigen-specific B cells, activated them with CD40 ligand, and characterised them by flow cytometry. Their capacity to induce T-cell activation was assessed in-vitro. In-vivo efficacy was evaluated in CT-26 syngeneic murine models following adoptive transfer of peptide-loaded CD40B cells, with or without anti–PD-1 therapy (pembrolizumab).ResultsImmunodominant epitopes (CD66c76–92 and CD66c141–156) elicited robust IFN-γ responses in vitro. CD40B cells showed enhanced expression of co-stimulatory molecules (CD80/CD86) and MHC class I/II. In vitro, CD66c-loaded CD40B induced significant CD4+ and CD8+ T-cell proliferation and activation. In vivo, adoptive transfer of CD66c-loaded CD40B cells augmented antigen-specific CD8+ T-cell responses, tumour-specific cytolysis of up to ~96% under optimised conditions, and tumour growth inhibition. Combination therapy with pembrolizumab showed synergistic effects, including enhanced intratumoral CD8+ T-cell infiltration, increased CD66c-specific IgG1 levels, and improved survival.ConclusionCD40-activated B cells targeting CD66c peptides may represent a promising preclinical platform for inducing antigen-specific cytotoxic T cell responses in CRC. This approach may improve responses to checkpoint blockade in preclinical settings; however, further validation in humanised models and clinical systems is required to establish its translational applicability.
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BibTeX
@article{yogananthan2026cd66ctargeted,
title = {{CD66c-targeted CD40B adaptive transfer to enhance cytotoxic T cell responses in colorectal cancer}},
author = {Dhanapal Yogananthan and Ashok Raj Kattur Venkatachalam and Ramanathan Muthiah},
journal = {Frontiers in Oncology},
year = {2026},
month = nov,
doi = {10.3389/fonc.2026.1848758},
url = {https://www.frontiersin.org/articles/10.3389/fonc.2026.1848758},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - CD66c-targeted CD40B adaptive transfer to enhance cytotoxic T cell responses in colorectal cancer
AU - Dhanapal Yogananthan
AU - Ashok Raj Kattur Venkatachalam
AU - Ramanathan Muthiah
PY - 2026
DA - 2026/11/09
JO - Frontiers in Oncology
DO - 10.3389/fonc.2026.1848758
UR - https://www.frontiersin.org/articles/10.3389/fonc.2026.1848758
AB - BackgroundColorectal cancer (CRC), particularly microsatellite-stable (MSS) CRC, shows a limited response to immune checkpoint inhibitors (ICIs). Novel strategies are needed to enhance antigen-specific T cell immunity. CD66c (CEACAM6) is a tumour-associated antigen overexpressed in CRC and involved in immune evasion. CD40-activated B cells (CD40B) can function as effective antigen-presenting cells (APCs) in adoptive immunotherapy.MethodsWe screened a CD66c-derived peptide library using IFN-γ ELISpot assays in peripheral blood mononuclear cells (PBMCs) from patients with CRC and healthy controls to identify immunodominant epitopes. We isolated antigen-specific B cells, activated them with CD40 ligand, and characterised them by flow cytometry. Their capacity to induce T-cell activation was assessed in-vitro. In-vivo efficacy was evaluated in CT-26 syngeneic murine models following adoptive transfer of peptide-loaded CD40B cells, with or without anti–PD-1 therapy (pembrolizumab).ResultsImmunodominant epitopes (CD66c76–92 and CD66c141–156) elicited robust IFN-γ responses in vitro. CD40B cells showed enhanced expression of co-stimulatory molecules (CD80/CD86) and MHC class I/II. In vitro, CD66c-loaded CD40B induced significant CD4+ and CD8+ T-cell proliferation and activation. In vivo, adoptive transfer of CD66c-loaded CD40B cells augmented antigen-specific CD8+ T-cell responses, tumour-specific cytolysis of up to ~96% under optimised conditions, and tumour growth inhibition. Combination therapy with pembrolizumab showed synergistic effects, including enhanced intratumoral CD8+ T-cell infiltration, increased CD66c-specific IgG1 levels, and improved survival.ConclusionCD40-activated B cells targeting CD66c peptides may represent a promising preclinical platform for inducing antigen-specific cytotoxic T cell responses in CRC. This approach may improve responses to checkpoint blockade in preclinical settings; however, further validation in humanised models and clinical systems is required to establish its translational applicability.
SN - 2234-943X
ER -