In vivo CAR-T seeks to move cell therapy from individualized ex vivo manufacturing toward direct immune-cell engineering inside the patient. Genetic payloads are delivered systemically to program endogenous immune cells in situ, potentially reducing manufacturing complexity, treatment delays and the need for lymphodepletion. The principal technical challenge shifts from manufacturing the cell product to achieving selective delivery, sufficient transduction, expansion and persistence in vivo.

The emerging landscape is splitting across several delivery architectures, each making a different trade-off between persistence, genomic integration, re-dosability, manufacturing complexity, and clinical maturity.

Engineered lentiviral vectors deliver a DNA CAR cassette directly to T cells, enabling durable, potentially permanent expression. They currently have the strongest clinical maturity, but face concerns around off-target transduction, genomic integration, long-term genotoxicity, and limited re-dosing.

Targeted lipid nanoparticles deliver CAR-encoding mRNA directly to immune cells. The approach is non-integrating, transient, and potentially repeat-doseable, with attractive manufacturing scalability. The main challenge is whether short-lived expression can generate sufficiently deep and durable clinical responses.

Circular or endless RNA aims to extend CAR expression while remaining non-integrating. The approach could offer a middle ground between transient mRNA and permanent integration, but remains less clinically validated and carries manufacturing and immunogenicity uncertainties.

These platforms use non-viral delivery of gene-editing systems to achieve durable genomic integration. They could combine long-term expression with non-viral manufacturing, but remain earlier stage with unresolved questions around editing efficiency, specificity, immune activation, and genotoxicity.

Virus-like particles, extracellular vesicles, AAV, direct protein, and other carriers offer different targeting and payload strategies, including potential access to T cells, NK cells, and myeloid cells. Most are earlier stage and remain highly dependent on platform-specific biodistribution, persistence, payload, and manufacturing performance.

LB2501 is an integrating, CD19/CD20 dual-targeted in vivo CAR-T for relapsed/refractory B-cell non-Hodgkin lymphoma.

LB2501 has generated the most developed clinical dataset of the three programs shown. In a Phase 1 study of 12 heavily pretreated patients with relapsed/refractory B-cell NHL, the higher dose cohort achieved 100% ORR (6/6) and 83% CR (5/6), with responses observed across DLBCL, mantle cell lymphoma, and follicular lymphoma.

The program also demonstrated single-dose in vivo CAR-T expansion without lymphodepletion, with CAR-T cells detectable in peripheral blood for up to 116 days. Early safety appears manageable, with no DLTs, serious adverse events, ICANS, or deaths reported; CRS and infusion reactions were limited to Grade 1–2. Translational data also showed broad T-cell integration without evidence of unintended transduction in the non-target lymphocyte populations tested.

KLN-1010 is an integrating, BCMA-targeted in vivo CAR-T delivered through Kelonia’s CD3-targeted lentiviral platform for relapsed/refractory multiple myeloma (rrMM).

KLN-1010 has shown a strong early efficacy signal in relapsed/refractory multiple myeloma. All 4 of the first treated patients, each with at least three prior lines of therapy, achieved MRD-negative responses at Month 1.

Importantly, these responses were achieved without lymphodepleting chemotherapy. The platform also demonstrated substantial in vivo expansion, with engineered CAR-T cells reaching as much as ~85% of circulating T cells, supporting the ability of the CD3-targeted lentiviral platform to generate and amplify CAR-T cells directly in patients.

ESO-T01 reprogram a patient’s T cells directly in vivo into BCMA-directed CAR-T cells for r/r multiple myeloma.

ESO-T01 has also demonstrated early clinical activity in relapsed/refractory multiple myeloma. In the first treated patient, the therapy produced strong CAR-T expansion with no detectable residual myeloma in bone marrow by Day 28.

Across the initial 5 patients, preliminary Phase 1 data showed an 80% ORR (4/5) with 3 complete responses, again without preparative chemotherapy. However, the safety profile is more concerning: all five patients experienced Grade ≥3 adverse events, including three cases of Grade 3 CRS.

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