{
  "abstract": "Background: CAR-T cells have shown limited efficacy against solid tumors, where they face two major challenges: restricted tumor infiltration and sustained intensive engagement that drive them to exhaustion. Conventional CAR design has largely emphasized high-affinity interactions with slow dissociation, further limiting tumor infiltration and exacerbating exhaustion and dysfunction. We hypothesize that most current CARs are kinetically over-stabilized for solid tumors and that a fast-on/fast-off, cheek-kiss mode of engagement permits transient CAR-antigen disengagement, thereby facilitating tumor infiltration and preserving CAR-T cell fitness in tumor mass. Methods: We identified two monoclonal antibodies targeting the same epitope of epidermal growth factor receptor with comparable kon but distinct koff rates: cetuximab (Cet) and its humanized derivative H1. CAR-T cells incorporating these binders were evaluated in vitro and in vivo. Large, established human tumor xenografts were treated with low-dose CAR-T cells in NSG mice to model conditions of limited T cell availability and sustained tumor antigen exposure. Results: Cet and H1 exhibited comparable kon but markedly different koff rates, with H1 displaying fast-off kinetics with approximately 18-fold shorter binding dwell time. As CARs, H1 showed reduced antigen occupancy and less stable tumor-T cell engagement than Cet. Despite comparable in vitro cytotoxicity, H1 CAR-T cells accumulated more efficiently following tumor stimulation. At high doses, both CAR-T cell products eradicated established tumors. Under low-dose conditions, however, H1 CAR-T cells exhibited superior expansion, persistence, tumor infiltration, and antitumor efficacy, whereas Cet CAR-T cells showed limited expansion and only transient tumor control. Cet CAR-T cells progressively downregulated surface CAR expression, increased PD-1 expression, and exhibited reduced tumor infiltration and impaired functional recovery. In contrast, H1 CAR-T cells preserved surface CAR expression, exhibited greater tumor infiltration, maintained a less exhausted, more central memory-like phenotype, and retained effector function. Conclusion: Fast-on/fast-off binding kinetics enhance CAR-T tumor infiltration, expansion, persistence, and functional fitness, resulting in improved control of established solid tumors. The data provides a rationale for shifting CAR design from affinity optimization toward kinetic optimization to improve the efficacy and safety of CAR-T therapy for solid tumors.",
  "abstract_shown": true,
  "affiliations": [
    "Augusta University"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "name": "R. Mao"
    },
    {
      "name": "H. Shi"
    },
    {
      "name": "M. S. Hussein"
    },
    {
      "name": "B. Karia"
    },
    {
      "name": "O. Koomson"
    },
    {
      "name": "R. Sadek"
    },
    {
      "name": "V. Kota"
    },
    {
      "name": "N. Gascoigne"
    },
    {
      "affs": [
        0
      ],
      "name": "Y. He"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/df6wegcyj3t0h.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.10.10.756030",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.10.10.756030v1.full",
  "id": "df6wegcyj3t0h",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.10.10.756030v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "immunology"
    ],
    [
      "openalex",
      "2730|CAR-T cell therapy research"
    ]
  ],
  "openalex": "W7221568130",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.10.10.756030v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/df6wegcyj3t0h.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:20Z",
      "native_id": "10.64898/2026.10.10.756030",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.10.10.756030v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:immunology",
      "subfield": "immunology"
    }
  ],
  "title": "Fast receptor-antigen dissociation kinetics promote CAR-T cell tumor infiltration, functional fitness, and antitumor efficacy in solid tumors",
  "title_text": "Fast receptor-antigen dissociation kinetics promote CAR-T cell tumor infiltration, functional fitness, and antitumor efficacy in solid tumors",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:20Z",
  "url": "https://research.draconitic.com/paper/df6wegcyj3t0h",
  "venue": "bioRxiv",
  "versions": []
}