Skip to content
ContentLora

    Tip: press / anywhere to search.

    technology

    In vivo CAR-T

    Also known as in vivo CAR T, in situ CAR-T, ESO-T01, KLN-1010

    In vivo CAR-T uses a gene-delivery vector to turn a patient's T cells into CAR-T cells inside the body, avoiding leukapheresis, lab manufacturing and lymphodepleting chemotherapy.[1] First myeloma trials report deep responses but also serious toxicity, and all data so far are early-phase.[2][3]

    Editor reviewedStrict sourcingUpdated Cancer immunotherapyHealth and medicineLife sciences
    Key facts

    In vivo CAR-T is an attempt to skip the bespoke manufacturing step of CAR-T. Instead of collecting a patient’s T cells and engineering them in a lab for weeks, a vector is infused that reprograms T cells inside the body.[4][1]

    How it works

    Standard CAR-T requires collecting blood, engineering and expanding T cells, and reinfusing them, a process of about 3 to 5 weeks.[4] ESO-T01 is a lentiviral vector encoding an anti-BCMA CAR, given as a single intravenous infusion without leukapheresis, ex vivo manufacturing or lymphodepleting chemotherapy.[1]

    Researchers describe the ex vivo route as lengthy and costly, which limits how many patients can get engineered T cells. They also note the limits of current in vivo methods: they rely either on short-lived expression or on DNA that inserts at random places in the genome.[5]

    Clinical evidence so far

    A phase 1 study published in Nature Medicine in April 2026 treated five heavily pretreated patients with relapsed or refractory multiple myeloma with ESO-T01. All were men, with a median of three prior lines of therapy.[6] Four responded, including three stringent complete remissions, with minimal residual disease negativity in all evaluable responders by day 60.[2] Safety was a concern: all five had grade 3 or higher adverse events, four had cytokine release syndrome, and one patient died from lesion-related spinal cord compression. The trial was stopped early in 2025.[3] There were no dose-limiting toxicities. Cytokine release syndrome (three grade 3 cases and one grade 2) was managed with corticosteroids, tocilizumab or supportive care, and the commonest problems were temporary drops in blood counts and reversible liver-enzyme rises. Median follow-up was only 6.0 months.[7]

    Kelonia’s KLN-1010, another in vivo BCMA CAR-T, has reported conference data: minimal residual disease negativity at one month in all four patients presented at ASH 2025 and in all 18 presented at ASCO 2026.[8] These results have not yet appeared in a peer-reviewed paper.[8]

    Gene editing in the body

    A March 2026 Nature study tested a more precise route in mice. It delivered crispr-cas9 together with a DNA template to insert a CAR gene at a T-cell-specific site in the genome, and generated therapeutic levels of CAR-T cells in humanised mouse models of blood and solid cancers.[9] This was preclinical work; no patient had been treated.[9]

    Why it matters

    If it works safely, in vivo CAR-T would remove the manufacturing step that makes CAR-T slow and patient-specific, and the lymphodepleting chemotherapy that precedes standard CAR-T.[1] The ESO-T01 investigators frame the goal as simplifying and speeding access to cell therapy.[6] Tumour-derived cell therapies face the same manufacturing burden; see tumor-infiltrating-lymphocyte-therapy. For how vectors carry genes into cells, see How gene therapy delivery works. The study authors describe their results as preliminary evidence of feasibility and safety.[2]

    Open questions

    Key unknowns are durability beyond a few months of follow-up, how to control early inflammatory toxicity, and whether the approach extends beyond B-cell and plasma-cell targets to solid tumours.[3][10]

    Questions readers ask

    How is in vivo CAR-T different from standard CAR-T?

    Standard CAR-T collects and engineers a patient's T cells in a lab over about 3 to 5 weeks. In vivo approaches such as ESO-T01 give a single intravenous infusion of a vector, without leukapheresis, ex vivo manufacturing or lymphodepleting chemotherapy.[4][1]

    Has in vivo CAR-T worked in patients?

    In a five-patient phase 1 myeloma study of ESO-T01, four patients responded, including three stringent complete remissions. Conference data on Kelonia's KLN-1010 also reported MRD-negative responses, but these are early results.[2][8]

    Is it safe?

    Not yet established. All five ESO-T01 patients had grade 3 or higher adverse events and one died from lesion-related spinal cord compression; the trial was stopped early in 2025.[3]

    Why not just keep making CAR-T in the lab?

    Researchers describe ex vivo manufacturing as lengthy and costly, which limits access. In vivo approaches aim to remove that step.[5]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      ESO-T01 is a lentiviral vector given as a single intravenous infusion that generates anti-BCMA CAR-T cells inside the body, without leukapheresis, ex vivo manufacturing or lymphodepleting chemotherapy. confirmedas of 2026-04-01

    2. [2]

      In a phase 1 study of ESO-T01 in five patients with relapsed or refractory multiple myeloma, four responded, including three stringent complete remissions. confirmedas of 2026-04-01

    3. [3]

      All five ESO-T01 patients had grade 3 or higher adverse events, four had cytokine release syndrome, one patient died from lesion-related spinal cord compression, and the trial was stopped early in 2025. confirmedas of 2026-04-01

    4. [4]

      CAR T-cell therapy collects a patient's T cells, genetically engineers them to make chimeric antigen receptors, grows them to hundreds of millions and returns them as a single infusion, a process NCI puts at about 3 to 5 weeks. confirmedas of 2025-02-26

    5. [5]

      Researchers describe ex vivo manufacturing of engineered T cells as lengthy and costly, limiting access, and current in vivo CAR-T methods as relying on either short-lived expression or random DNA integration. confirmedas of 2026-03-18

    6. [6]

      The ESO-T01 investigators wrote that in vivo CAR-T generation can bypass ex vivo manufacturing and lymphodepletion, potentially simplifying and speeding access to cell therapy; their five patients were heavily pretreated men with a median of three prior lines of therapy. confirmedas of 2026-03-25

    7. [7]

      In the ESO-T01 study there were no dose-limiting toxicities; cytokine release syndrome (three grade 3, one grade 2) was managed with corticosteroids, tocilizumab or supportive care, and the most frequent toxicities were transient low blood counts and reversible liver-enzyme rises, over a median follow-up of 6.0 months. confirmedas of 2026-03-25

    8. [8]

      Conference data on Kelonia's in vivo BCMA CAR-T candidate KLN-1010 reported minimal residual disease negativity at one month in every myeloma patient presented, four at ASH 2025 and 18 at ASCO 2026; the data are early and not yet peer-reviewed. reportedas of 2026-06-02

    9. [9]

      A 2026 Nature study used CRISPR-Cas9 delivered in vivo with a DNA template to insert a CAR gene at a T-cell-specific site, generating therapeutic levels of CAR-T cells in humanised mouse models; it was a preclinical study. confirmedas of 2026-03-18

    10. [10]

      NCI identifies three obstacles for CAR T cells in solid tumours: few suitable surface antigens, an immunosuppressive tumour environment, and molecular variation between and within tumours. confirmedas of 2025-02-26

    Revision history (2)
    1. Page created.
    2. Refresh: added ESO-T01 toxicity detail, the manufacturing-cost rationale and preclinical CRISPR-based in vivo CAR insertion.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "In vivo CAR-T." ContentLora, updated Oct 10, 2026. https://contentlora.com/wiki/in-vivo-car-t

    Spotted an error? Suggest a correction or emailcorrections@contentlora.com.

    Keep exploring

    Connections
    CAR-T cell therapy Aims to replace manufactu…
    ☰ Contents