Genocury’s In Vivo CAR-T JY231 Shows Early Promise in Refractory Neurologic Autoimmune Diseases
A Chinese research team has reported encouraging early clinical results for JY231, an investigational lentiviral in vivo CD19 CAR-T therapy that generates therapeutic CAR-T cells directly inside the patient’s body, potentially eliminating two of the major complexities associated with conventional CAR-T treatment: ex vivo cell manufacturing and lymphodepleting chemotherapy.
Researchers from Tongji Hospital, Huazhong University of Science and Technology, working with Shenzhen Genocury Biotech, treated 16 patients with refractory neurologic autoimmune disorders with the experimental therapy. The results were published September 2 in the New England Journal of Medicine.
Following a single intravenous administration, JY231 induced expansion of CD19-directed CAR-T cells in vivo, produced complete peripheral B-cell depletion and was associated with preliminary clinical improvements across the disease groups, with manageable adverse effects. Importantly, the patients in this report received the treatment without lymphodepletion.
The findings provide early human evidence that an off-the-shelf lentiviral vector could potentially generate functional CAR-T cells inside patients with autoimmune diseases, offering a fundamentally different approach from today’s personalized, ex vivo-manufactured CAR-T therapies.
16 Patients With Severe Neurologic Autoimmune Disease
The early clinical experience included 16 patients with refractory neurologic autoimmune disorders, including progressive multiple sclerosis (PMS), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), generalized myasthenia gravis (gMG) and idiopathic inflammatory myopathy (IIM).
The study is part of an early exploratory program investigating in vivo CD19 CAR-T therapy for refractory autoimmune diseases. ClinicalTrials.gov lists the related study, NCT07059169, as an open-label, single-arm investigator-initiated study designed to assess the safety, tolerability and preliminary efficacy of in vivo CAR-T therapy.
Rather than collecting T cells from each patient and genetically modifying them in a manufacturing facility, JY231 uses a lentiviral vector designed to deliver the CAR construct to T cells inside the body.
The result is effectively an in vivo CAR-T “factory”: the patient’s own circulating T cells are genetically programmed to recognize CD19, a surface protein expressed on B cells.
JY231 Generates CAR-T Cells Inside the Patient
This distinction could have major implications for how CAR-T therapies are produced and delivered.
Conventional autologous CAR-T therapy typically involves several steps: collecting a patient’s T cells through leukapheresis, genetically engineering those cells outside the body, expanding them in a specialized manufacturing facility, performing quality-control testing, administering lymphodepleting chemotherapy and finally reinfusing the manufactured CAR-T product.
JY231 seeks to bypass much of that process.
Genocury’s proprietary in vivo platform uses a lentiviral vector to deliver the CAR genetic payload directly to circulating T cells, allowing functional CD19 CAR-T cells to be generated and expanded within the patient. Genocury describes its platform as an in vivo CAR-T technology intended to advance universal cell and gene therapies.
In the newly reported autoimmune-disease cohort, researchers observed robust expansion of CAR-T cells following treatment, demonstrating that the vector could successfully generate a therapeutically relevant cellular response inside the body.
Rapid and Complete B-Cell Depletion
The engineered CAR-T cells subsequently targeted CD19-positive B cells, resulting in rapid and complete peripheral B-cell depletion.
That pharmacodynamic effect is central to the therapeutic hypothesis behind CD19 CAR-T therapy in autoimmune disease.
B cells play important roles in antigen presentation, immune signaling and production of pathogenic autoantibodies. Profound B-cell depletion may therefore remove pathogenic B-cell populations more comprehensively than conventional antibody-based B-cell therapies and potentially allow the immune system to reconstitute with a less autoreactive B-cell repertoire.
The concept has already attracted considerable interest following encouraging results from conventional ex vivo CD19 CAR-T therapy.
For example, an earlier NEJM case series of 15 patients with severe autoimmune diseases found that autologous CD19 CAR-T therapy produced deep B-cell depletion and sustained clinical responses in systemic lupus erythematosus, idiopathic inflammatory myositis and systemic sclerosis.
However, those patients received conventionally manufactured CAR-T cells following fludarabine/cyclophosphamide lymphodepletion. JY231 is attempting to achieve a similar immune-reset concept without either ex vivo CAR-T manufacturing or, in the newly reported cohort, lymphodepleting chemotherapy.
Signs of an Immune “Reset”
The investigators reported clinical and biomarker improvements across the disease groups during approximately six months of observation.
According to a Nature report discussing the findings, CAR-T expansion was followed by reductions in B cells and disease-associated autoantibodies. As B cells subsequently returned, the newly emerging populations did not show the same pathogenic autoantibody pattern observed before treatment, raising the possibility of an immune-system “reset.”
Patients with multiple sclerosis showed improvements in measures of motor and cognitive function and fatigue, while patients with muscle-related autoimmune disorders demonstrated improvements in muscle strength and reduced inflammation.
These observations remain preliminary, however. The study included only 16 patients, lacked a randomized control group and currently provides relatively short follow-up.
Dai-Shi Tian, a neurologist at Tongji Hospital and senior author of the NEJM report, emphasized that the findings represent promising signals rather than definitive evidence of efficacy or durable immune tolerance.
No Lymphodepletion in the Reported Cohort
One of the most consequential aspects of the results is that the reported patients received JY231 without lymphodepleting chemotherapy.
Traditional CAR-T treatment commonly uses fludarabine and cyclophosphamide before CAR-T infusion to create an immune environment that supports expansion of the engineered cells. But lymphodepletion also contributes to cytopenias, infections and other treatment-related risks.
The ability of JY231-generated CAR-T cells to expand without such conditioning could therefore substantially simplify treatment if confirmed in larger trials.
Genocury had previously reported a similar proof-of-concept in oncology. In 2025, the company disclosed that a patient with relapsed/refractory diffuse large B-cell lymphoma achieved complete remission following its in vivo CD19 CAR-T treatment without lymphodepletion. The patient generated substantial CAR-T expansion after treatment, according to Genocury’s earlier clinical announcement.
The autoimmune results now broaden the potential application of the platform beyond cancer.
Potentially Transforming CAR-T Manufacturing
Perhaps the biggest strategic implication of JY231 is not simply another application of CD19 CAR-T therapy, but a potential change in how CAR-T medicines are delivered.
Today’s autologous CAR-T therapies are highly personalized products. Manufacturing can be complex, expensive and time-consuming, requiring specialized cell-processing facilities and sophisticated supply chains.
In vivo CAR-T could theoretically convert that individualized manufacturing process into something closer to administration of a conventional gene-therapy product.
A ready-to-use vector could be administered intravenously, find the appropriate T cells inside the patient, genetically program those cells and allow the resulting CAR-T population to expand in vivo.
In simplified terms:
Conventional CAR-T:
Patient → T-cell collection → ex vivo engineering → cell expansion → quality testing → lymphodepletion → CAR-T infusion
JY231 in vivo CAR-T:
Patient → single IV vector infusion → CAR-T cells generated and expanded inside the body
If that model proves safe, controllable and reproducible in larger studies, it could reduce manufacturing complexity and potentially broaden access to CAR-T technology.
Safety Will Be Critical
The same characteristics that make in vivo CAR-T attractive also create important scientific and regulatory questions.
With conventional CAR-T manufacturing, cells can be characterized and quality-tested before they are infused. With in vivo engineering, genetic modification occurs directly inside the patient.
Future studies will therefore need to carefully characterize the specificity of lentiviral transduction, the identity of transduced cell populations, CAR expression and persistence, insertional risks, long-term immune effects and the ability to control excessive CAR-T activity.
In the 16-patient NEJM report, adverse effects were described as manageable, providing encouraging initial evidence of feasibility. However, the small cohort and limited follow-up mean that uncommon or delayed adverse events cannot yet be adequately assessed.
Long-term follow-up will be especially important for an integrating lentiviral vector.
China Emerges as a Hotspot for In Vivo CAR-T
JY231 is part of a rapidly developing field of in vivo immune-cell engineering, with researchers and biotechnology companies exploring several delivery technologies—including lentiviral vectors and lipid nanoparticle/mRNA systems—to generate CAR-T cells directly inside patients.
Genocury is among the Chinese companies pushing this concept into human studies. The Shenzhen-based biotechnology company says it has established a proprietary in vivo CAR-T technology platform and is developing universal cell and gene therapies. Genocury’s corporate website describes the company as focused on developing in vivo CAR-T technologies and related cell and gene therapies.
The company’s clinical pipeline also includes studies of JY231 in relapsed or refractory B-cell malignancies. ClinicalTrials.gov lists JY231 study NCT06890065 in relapsed/refractory B-cell lymphoma or leukemia.
An Early but Potentially Important Proof of Concept
The new results should be interpreted cautiously. Sixteen patients in an uncontrolled early-stage study cannot establish that JY231 is effective, nor can short-term follow-up demonstrate durable remission or long-term safety.
Nevertheless, the study addresses several major questions simultaneously.
JY231 demonstrated that a systemically administered lentiviral vector could generate expanding CD19 CAR-T cells inside patients; those cells produced profound B-cell depletion; treatment was accomplished without lymphodepletion in this cohort; and preliminary clinical and biomarker improvements were observed across several difficult-to-treat neurologic autoimmune diseases.
If these findings can be replicated in larger controlled studies with longer follow-up, the implications could extend well beyond autoimmune disease.
The ultimate promise of in vivo CAR-T is to transform CAR-T from a complex, patient-specific manufacturing procedure into a more readily administered therapeutic platform. JY231’s early results suggest that Chinese researchers are now testing that possibility directly in patients.
References
- Cheng Y-H, Shang K, Qin C, et al. Lentiviral In Vivo CD19 CAR T-Cell Therapy in Neurologic Autoimmune Disorders. New England Journal of Medicine. Published online September 2, 2026;395:926-929.
NEJM — Full Article - Nature. Immune therapy engineered inside the body eases multiple sclerosis. September 2026.
Nature — JY231/In Vivo CAR-T Coverage - ClinicalTrials.gov. CAR-T Therapy for Refractory Autoimmune Diseases. NCT07059169.
ClinicalTrials.gov — NCT07059169 - Mackensen A, et al. CD19 CAR T-Cell Therapy in Autoimmune Disease — A Case Series with Follow-up. New England Journal of Medicine.
NEJM — Conventional CD19 CAR-T in Autoimmune Disease - Shenzhen Genocury Biotech. Company and in vivo CAR-T technology platform.
Genocury Biotech - Genocury Biotech. Groundbreaking Advance in Relapsed/Refractory DLBCL Through Pioneering In Vivo CD19 CAR-T Therapy. April 30, 2025.
Genocury — In Vivo CAR-T DLBCL Clinical Update - ClinicalTrials.gov. JY231 Injection for the Treatment of Relapsed/Refractory B-Cell Lymphoma/Leukemia. NCT06890065.
ClinicalTrials.gov — NCT06890065
