First-in-human in vivo CAR T-cell generation using a CD8-targeted lipid nanoparticle platform in relapsed/refractory B-cell lymphoma.

7014 Background: R/R B-cell lymphomas remain challenging despite advances in ex vivo CAR T-cell therapies, which are limited by complex logistics, manufacturing delays, and cost. In vivo CAR T-cell generation using targeted delivery offers a paradigm shift. We report the first-in-human study of a CD8-targeted lipid nanoparticle (CD8-tLNP) platform to generate functional CD19 CAR T cells in vivo. Methods: The CD8-tLNP was constructed by conjugating an anti-CD8 VHH to the surface of LNP encapsulating mRNA coding a CD19-directed chimeric antigen receptor, Safety, pharmacodynamics, and tolerability were first evaluated in non-human primates following intravenous administration. Subsequently, 4 patients with R/R CD19⁺ B-cell lymphoma received four intravenous doses of CD19-CD8-tLNPs. Peripheral blood was collected at serial time points to assess CAR⁺ CD8⁺ T cells, B-cell depletion, cytokine levels, and clinical laboratory parameters. Antitumor activity was evaluated by PET-CT imaging, and adverse events were graded according to standard criteria. Results: The platform showed favorable safety and PD in monkeys. To date, seven patients with relapsed or refractory CD19⁺ B-cell lymphoma have been treated. Among the evaluable patients, two patients achieved PR with decreased tumor lesions, one maintained SD by day 28; four patient remains pending efficacy evaluation. Following i.v. administration, CAR gene and surface expression in peripheral blood CD8⁺ T cells peaked within 4–6 hours and declined thereafter, consistent with transient in vivo CAR T-cell generation. This was accompanied by rapid and near-complete peripheral B-cell clearance, with complete depletion (<1 B cell/μL) observed between 12 hours and day 3. Three booster doses administered at 3-day intervals sustained complete B-cell depletion and CAR T-cell activity. The treatment was generally well tolerated. No cytokine release syndrome of grade ≥2 was observed. Transient increases in CRP and ferritin were observed and were clinically manageable, without significant elevations in liver enzymes or prolonged cytopenias. Two patients showed naïve B-cell reconstitution by day 32 or 47. Conclusions: This first-in-human study demonstrates the feasibility and early clinical activity of in vivo CAR T-cell generation using a CD8-targeted LNP platform in patients with relapsed or refractory B-cell lymphoma. The approach enables rapid, transient CAR T-cell expression, repeatable dosing, and a favorable safety profile without lymphocyte clearance and complex manufacturing in ex vivo CAR T-cell. These findings provide clinical proof of concept for a scalable, off-the-shelf CAR T-cell therapy and support further clinical evaluation in hematologic malignancies. Clinical trial information: 2025-02-02.