A small study used a lentivirus to generate CD19 CAR‑T cells inside patients with relapsing multiple sclerosis. Results show rapid B‑cell depletion and clinical improvement, but safety and whether this adds value over existing B‑cell therapies remain unresolved.
A lentiviral in vivo approach produced CAR‑T cells that caused rapid, complete peripheral B‑cell depletion and transient drops in immunoglobulins, with later repopulation dominated by naive clones.
The study reported evidence of reduced MS disease activity, but follow‑up was short and the trial did not answer whether this approach outperforms existing B‑cell depleting or immune‑reprogramming therapies.
Open practical questions include whether anti‑CD19 CAR‑T is necessary to affect CNS B cells and plasma cells, whether it eliminates oligoclonal bands, and how cost, manufacturing, and safety compare with current options.
Chimeric antigen receptor T cells combine antibody‑target recognition with T‑cell killing. Traditional CAR‑T for B‑cell targets is made by collecting a patient's T cells, genetically modifying them ex vivo, expanding them, then reinfusing them. That process is time‑consuming and costly.
A recent small study (Cheng et al., N Engl J Med, 2026) used a lentivirus delivered into patients to convert their own T cells into CD19 CAR‑T cells in vivo. The procedure did not require preconditioning to clear the immune system.
The in vivo CAR‑T expanded rapidly and produced complete peripheral B‑cell depletion. Immunoglobulin levels fell temporarily. When B cells returned more than two months later, the repopulation was dominated by naive B cells and the original B‑cell receptor clonotypes were completely replaced. The authors described that pattern as molecular evidence consistent with a systemic immunologic reset.
The paper reported evidence of reduced disease activity in relapsing MS. The blog commentary highlighted that the in vivo CAR‑T produced effects similar to CAR‑T made ex vivo in terms of B‑cell suppression and clinical impact in the short term.
Because the lentivirus inserts genetic material into host cells, there is a theoretical risk that an integration event could activate oncogenes and cause clonal expansion or cancer. The authors suggest long‑term monitoring, recommending at least ten years of follow‑up to watch for late adverse events. The commentary also cited published concerns about insertional mutagenesis in in vivo gene therapy contexts.
Practical comparisons with existing therapies
The blog author raised practical questions: do we need anti‑CD19 CAR‑T to control relapsing MS, or can existing anti‑CD20 therapies and immune‑reconstitution treatments (IRT) such as cladribine achieve the same clinical outcomes? The argument presented is that stopping peripheral B cells should prevent their entry into the CNS, and that depleting B cells in blood might be sufficient for many patients.
The blog contrasted the high cost of commercial autologous CAR‑T for cancer with suggestions that some centers can produce lower‑cost products. The author noted reports that Chinese groups are advancing CAR‑T approaches and suggested in vivo methods could simplify scale‑up, though the report itself does not present a definitive cost analysis.
Follow‑up data addressing long‑term safety, effects on CNS B cells and oligoclonal bands, direct comparisons versus anti‑CD20 and IRTs, and broader trial results will be needed to judge whether in vivo CAR‑T should be adopted for MS. Extended monitoring for insertional mutagenesis and tumor formation is required by the investigators.
CAR-T’s commercial challenge is making thousands of patient-specific manufacturing runs behave like one reliable system. "In vivo" production techniques could be one solution.
Renier Brentjen, an early pioneer of CAR T cell therapy, is working on the next generation of these living drugs that can hopefully treat solid tumors, too.
Predictive cell intelligence can be used to reveal cellular states and emerging cellular trajectories earlier in the manufacturing process and to support more informed bioprocessing decisions. The post Current Challenges in CAR T Manufacturing appeared first on GEN - Genetic Engineering and Biotechnology News .
A potentially safer, simpler way to create CAR T cells in the body could bring this powerful therapy to the masses. The post Single CAR T Injection Eases Multiple Sclerosis Symptoms in Small Trial appeared first on SingularityHub .
A new experimental cell therapy that pairs a patient’s own red blood cells with myelin protein fragments safely calmed the immune system and helped dampen the inflammatory attack that drives multiple sclerosis (MS), according to results from an early-stage clinical trial. The novel approach works by retraining the body
T cell immunologists have to embrace the fact that B cell depleting therapies are active. One way is to focus on the B or the other way is to shoe-horn the T into the B. The best way is to create your hypothesis and test it and put it to the Sword or not or […]
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