CLL-1-Targeted In Vivo CAR-T Cell Immunotherapy for Relapsed/Refractory Acute Myeloid Leukemia

This is a single-center, open-label, single-arm, phase 1 dose-escalation study to evaluate the safety, tolerability, preliminary efficacy, and cellular kinetics of SL1CC Injection, an in vivo CAR-T therapy targeting CLL-1, in patients with relapsed or refractory acute myeloid leukemia (R/R AML; acute promyelocytic leukemia excluded). SL1CC Injection is administered as a single intravenous infusion without lymphodepleting conditioning. 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 the occurrence of dose-limiting toxicities (DLTs). Treatment-emergent adverse events and serious adverse events, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), hematologic toxicity, organ toxicity, and other immune therapy-related toxicities, will be assessed. Preliminary antitumor activity, assessed by composite complete remission (CR/CRi) and measurable residual disease (MRD) status according to the European LeukemiaNet (ELN) 2022 criteria, and the expansion and persistence of CAR-T cells in peripheral blood will also be evaluated.

Inclusion Criteria: * Voluntarily agrees to participate in the study, has signed the informed consent form, and is willing and able to comply with scheduled visits, study treatment, laboratory tests, and other study procedures. * Diagnosis of relapsed or refractory acute myeloid leukemia (AML), excluding acute promyelocytic leukemia (APL), according to the 2022 World Health Organization (WHO) classification, meeting at least one of the following: * Relapsed AML: Reappearance of leukemic cells in the peripheral blood after achieving complete remission (CR), bone marrow blasts ≥5% (excluding bone marrow regeneration after consolidation chemotherapy or other non-leukemic causes), or the presence of extramedullary leukemic infiltration. * Refractory AML: Newly diagnosed AML with no response after two courses of standard induction therapy; relapse within 12 months after achieving CR followed by consolidation/intensification therapy; relapse more than 12 months after CR with failure to respond to conventional chemotherapy; two or more relapses; or persistent extramedullary leukemia. * CLL-1 expression ≥50% on AML blasts, confirmed by flow cytometry on bone marrow or peripheral blood samples at the local certified laboratory. * Patients with targetable mutations (e.g., FLT3, IDH1/2, NPM1, or KMT2A rearrangement) must have received, be intolerant to, or be ineligible for the corresponding approved targeted therapy. * Recovered from acute toxicities of prior antileukemic therapy to ≤ Grade 1 (CTCAE v6.0) before SL1CC infusion, except for alopecia and hematologic abnormalities attributable to the underlying disease. * Male or female participants aged 18 to 75 years, inclusive. * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. * Estimated life expectancy of more than 3 months from the date of signing the informed consent form. * Adequate renal, hepatic, cardiac, and pulmonary function, defined as follows: * Creatinine clearance (estimated by the Cockcroft-Gault formula) ≥60 mL/min or serum creatinine ≤1.5 × the upper limit of normal (ULN); * Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST)≤2.5×upper limit of normal (ULN), total bilirubin≤1.5×ULN; * Cardiac ejection fraction≥50%, no pericardial effusion on echocardiography, and no significant abnormalities on electrocardiogram (ECG); * No clinically significant pleural effusion, and oxygen saturation \>92% on room air at baseline. * Participants of reproductive potential must agree to use highly effective contraception before enrollment and for at least 12 months after SL1CC infusion. A negative serum pregnancy test is required for women of childbearing potential at screening. Participants must immediately notify the investigator if pregnancy occurs or is suspected. Exclusion Criteria: * The patient has severe cardiac dysfunction, or left ventricular ejection fraction (LVEF) \