Legend Biotech's in vivo CAR-T LB2501 hits 100% ORR in NHL Phase 1

Legend Biotech has reported early clinical data for LB2501, its investigational in vivo CAR-T candidate targeting both CD19 and CD20, showing a 100% objective response rate and an 83.3% complete response rate at the higher of two dose levels tested in patients with relapsed or refractory B-cell non-Hodgkin lymphoma. The data were presented in a late-breaking session at the European Hematology Association congress on 14 June 2026.

The ongoing Phase 1 dose-escalation study enrolled 12 patients who had received a median of three prior lines of therapy, with 58.3% refractory to their most recent treatment. At dose level 2 (DL2), all six patients responded and five achieved a complete response, spanning diffuse large B-cell lymphoma, mantle cell lymphoma, and follicular lymphoma subtypes. Across both dose levels, the overall response rate was 50% and the complete response rate 41.7%. All DL2 responses were ongoing at the data cutoff.

Safety and pharmacokinetics

The safety readout is notable for its absence of severe events. No dose-limiting toxicities, serious adverse events, neurotoxicity, or deaths were recorded. Cytokine release syndrome occurred in 66.7% of patients and infusion-related reactions in 75%, but all were Grade 1 or 2. Only four patients received tocilizumab, and none required glucocorticoids for CRS management. Pharmacokinetic analyses confirmed dose-dependent in vivo CAR-T expansion in all DL2 patients and in five of six DL1 patients, with CAR-T cells detectable in peripheral blood for up to 116 days. Crucially, the viral vector cleared from peripheral blood to undetectable levels within 24 hours, and vector integrations were characterised as highly polyclonal, which the company says supports a favourable safety profile for the in vivo engineering approach.

The defining feature of LB2501 is its mode of delivery: rather than extracting, engineering, and reinfusing a patient's T cells ex vivo, the therapy uses a lentiviral vector administered intravenously to generate CAR-T cells directly inside the body. This approach, if validated in larger studies, could sidestep the lengthy and expensive manufacturing process that constrains access to current approved CAR-T products.

Market context and competitive landscape

The approved ex vivo CAR-T field is dominated by a small number of commercial products, including Legend's own CARVYKTI (ciltacabtagene autoleucel), developed in partnership with Johnson and Johnson for relapsed or refractory multiple myeloma. The in vivo CAR-T space is considerably earlier in development but has attracted significant industry interest as a potential route to off-the-shelf scalability. Several academic groups and emerging biotechs are pursuing viral and non-viral in vivo delivery strategies, though none has yet reached late-stage trials. Legend is positioning LB2501 as a potential first-in-class asset in this sub-category, though that designation rests on Phase 1 data from just 12 patients.

The absence of lymphodepletion is a clinically meaningful differentiator from standard ex vivo CAR-T protocols, which typically require chemotherapy conditioning that adds toxicity and hospitalisation burden. Regulators and payers will want to see durability data and a larger safety dataset before drawing firm conclusions, and the dose-escalation study is still ongoing. The company said it plans to identify a recommended Phase 2 dose as the study progresses.

Lei Fan, professor and administrative director of haematology at Jiangsu Province Hospital, said the responses at DL2, combined with the favourable safety profile and the absence of lymphodepletion, "support further investigation of LB2501 as a novel in vivo CAR-T approach." Fan disclosed a consulting and advisory relationship with Legend Biotech.

With over 3,000 employees and CARVYKTI as its commercial anchor, Legend enters the in vivo CAR-T race from a position of manufacturing and regulatory experience that earlier-stage competitors lack. The key near-term milestones are a recommended Phase 2 dose determination and durability follow-up across the DL2 cohort.