CD19 Sequential CD22 In Vivo CAR-T Cell Immunotherapy for Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia - NCT07927816

Sponsor: Liping Dou Conditions: Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia, In Vivo CAR-T, B-Cell Acute Lymphoblastic Leukemia This is a single-center, open-label, single-arm, prospective, investigator-initiated dose-escalation study to evaluate the safety, tolerability, preliminary efficacy, and cellular kinetics of an in vivo CAR-T cell immunotherapy targeting CD19 sequentially followed by CD22, in patients with relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL). The investigational product is a targeted lentiviral vector that transduces the patient's endogenous T/NK cells in situ; no leukapheresis, ex vivo manufacturing, or lymphodepleting conditioning is required. Participants receive an intravenous infusion of CD19-targeted in vivo CAR-T on Day 0, followed by an intravenous infusion of CD22-targeted in vivo CAR-T on Day 7. Before the Day 7 infusion, the investigator will assess each participant to determine whether the second infusion should proceed, based on: (i) the proportion of CAR-positive T/NK cells in peripheral blood, which reflects the success of in vivo transduction and early expansion after the first infusion; (ii) the maximum grade and current control of adverse events occurring after the first infusion, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS); and (iii) the participant's general condition, including Eastern Cooperative Oncology Group (ECOG) performance status and vital organ function (cardiac, hepatic, renal, pulmonary, and coagulation). The second infusion will be postponed or cancelled if any of these assessments indicates that the risk outweighs the benefit, for example grade \>=3 CRS or grade \>=2 ICANS that has not resolved to grade \<=1, or investigator-judged deterioration in organ function. Dose escalation follows a traditional 3+3 design with planned dose levels of 1×10\^9, 3×10\^9, and 6×10\^9 transducing units (TU), guided by dose-limiting toxicities (DLTs) assessed during Days 0-28; higher dose levels may be explored if the maximum tolerated dose is not reached. Treatment-emergent adverse events and serious adverse events, including CRS, immune effector cell-associated neurotoxicity syndrome (ICANS), hematologic toxicity, and organ toxicity, will be assessed. Preliminary antitumor activity will be evaluated by objective response rate (ORR), overall survival (OS), and progression-free survival (PFS), and the expansion and persistence of in vivo-generated CAR-T cells in peripheral blood will also be evaluated. This is a single-center, single-arm, open-label, prospective, investigator-initiated clinical study of CD19 sequential CD22 in vivo CAR-T cell immunotherapy in adults with R/R B-ALL whose tumor cells express CD19 and CD22. The investigational product is an engineered lentiviral vector in which the receptor-binding domain of the viral envelope has been mutated to abolish its native pantropic infectivity, and a targeting module composed of an anti-CD7 nanobody (VHH) and a T/NK-cell-specific ligand (CD58 extracellular domain) has been incorporated into the envelope, enabling specific transduction of circulating T cells and NK cells in situ and expression of a CAR directed against CD19 (first infusion) or CD22 (second infusion); no leukapheresis, ex vivo manufacturing, or lymphodepleting conditioning is required. Treatment consists of an intravenous infusion of CD19-targeted in vivo CAR-T on Day 0 and an intravenous infusion of CD22-targeted in vivo CAR-T on Day 7. Before the second infusion, the investigator will assess each participant to determine whether the second infusion should proceed, based on: (i) the proportion of CAR-positive T/NK cells in peripheral blood, used to evaluate the efficiency of in vivo transduction and early expansion after the first infusion; (ii) the maximum grade, current grade, and response to management of CRS, ICANS, and other adverse events occurring after the first infusion; and (iii) general condition, including ECOG performance status, vital organ function (cardiac, hepatic, renal, pulmonary, and coagulation), and infection status. Participants who meet the criteria for continued dosing will receive the second infusion as planned. The second infusion will be postponed if grade \>=3 CRS or grade \>=2 ICANS occurs and does not resolve to grade \<=1, or if the investigator judges that continued dosing carries a risk exceeding the potential benefit; if the participant does not recover to a state permitting dosing within the prespecified window, the second infusion will be cancelled and the participant will continue protocol-specified safety follow-up and efficacy assessment. Three dose levels are planned (1×10\^9, 3×10\^9, and 6×10\^9 TU) using a traditional 3+3 escalation design, and the DLT observation window is Days 0-28 after treatment; upon completion of DLT observation at the highest planned dose level without reaching the maximum tolerated dose (MTD), the investigator may explore higher dose levels based on accumulated safety and pharmacodynamic data. Planned enrollment is 12 participants. The study includes a screening period (within 28 days), a treatment period, and a follow-up period of up to 24 months. Safety assessments include adverse events and serious adverse events graded per NCI CTCAE v5.0, with CRS and ICANS graded per the ASTCT consensus criteria; hematologic toxicity, infection, organ toxicity, hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS), tumor lysis syndrome (TLS), and viral shedding (peripheral blood, saliva, and urine) are also monitored. Disease response is assessed by bone marrow morphology and multiparameter flow cytometry (CR and CRi), with measurable residual disease (MRD) assessed in bone marrow and cerebrospinal fluid. Exploratory cellular kinetics include peripheral blood CAR transgene copies (qPCR) and CAR-positive cell counts, with sampling planned on Days 2, 4, 6, 8, 10, 12, 14, 17, 21, 24, and 28 and at Months 2, 3, 6, 9, and 12 after infusion, and derivation of peak expansion (Cmax), time to peak (Tmax), and the area under the curve from Day 0 to Day 28 (AUC0-28d). Because the investigational product is an integrating lentiviral vector, participants will be enrolled in a long-term safety follow-up program for the detection of delayed adverse events, in accordance with the applicable guidance on gene therapy products; the duration, schedule, and responsible parties are specified in the protocol.