Research Appraisals
Evidence-based critical appraisals of the latest medical research, systematically evaluated using Oxford CEBM methodology.
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Blood
A phase 1/2 study of donor-derived anti-CD33 CAR T-cell therapy (VCAR33) for relapsed/refractory AML after allogeneic HCT
VCAR33, a donor-derived CD33-directed chimeric antigen receptor T-cell (CAR T) product, was developed to decrease relapse of high-risk acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) after allogeneic hematopoietic cell transplantation (alloHCT). We describe preclinical characterization of the VCAR33 construct, which was optimized for long-term antitumor surveillance based on killing and persistence assays. Prior to its use in post-alloHCT maintenance, we evaluated safety and efficacy of VCAR33 in a phase 1/2 clinical study for adults with relapsed or measurable residual disease (MRD)-positive CD33+ AML/MDS after alloHCT. Fifteen patients received VCAR33 across 2 arms stratified by disease burden: 7 patients in arm A (bone marrow blasts ≥5%) at dose level 1 (DL1; 1 × 106 CAR+ Ts per kg) and 8 patients in arm B (bone marrow blasts <5%) at DL1 (n = 5) and DL2 (3 × 106 CAR+ Ts per kg; n = 3). The study ended for nonsafety reasons before escalation to DL3 (1 × 107 CAR+ Ts per kg) and maximum tolerated dose was not determined. The most common treatment-related adverse event was cytokine release syndrome (93.3%; all <grade 3). Four patients (26.7%) experienced immune cell-associated neurotoxicity syndrome (1 ≥grade 3) and 1 patient (6.7%) had grade 3 acute graft-versus-host disease within 28 days of VCAR33 infusion. Fourteen patients (93.3%) had transient VCAR33 expansion. Overall response rate was 20%: 2 patients had complete remission with incomplete count recovery in arm A and 1 arm B patient achieved MRD clearance. This allogeneic CAR T product demonstrated acceptable safety and preliminary antileukemic activity. This trial was registered at www.clinicaltrials.gov as #NCT05984199.
25 Apr 2026
Read appraisal →Cancer immunology, immunotherapy : CII
A phase I, single-arm, open-label, dose-escalation, multicenter study of SAR445419, an off-the-shelf, ex vivo expanded allogeneic natural killer cell product, in participants with relapsed or refractory acute myeloid leukemia
BACKGROUND: SAR445419 is an investigational, off-the-shelf, allogeneic NK cell therapy derived from donor peripheral blood mononuclear cells and expanded ex vivo using PM21 particles. METHODS: This multicenter, Phase 1, dose-escalation study (NCT05712278) evaluated optimal dose(s), safety, and tolerability of SAR445419 in adults (aged ≥ 18 years) with relapsed/refractory acute myeloid leukemia (R/R AML). Following lymphodepleting chemotherapy (fludarabine 30 mg/m2/day and cytarabine 2 g/m2/day for 5 days), participants received six intravenous SAR445419 (1 × 109 and 3 × 109 NK cells/dose) doses, starting with the lower dose. The primary endpoint was the incidence of dose-limiting toxicities (DLTs), and key secondary endpoints included adverse events (AEs), hematological recovery, hematopoietic stem cell transplantation, and response rate. RESULTS: Of the 12 planned participants, 7 patients were enrolled, of whom 6 received SAR445419 before sponsor decided early study termination for reasons unrelated to safety or efficacy. No DLTs were observed. All participants experienced treatment-emergent adverse events (TEAEs); six had grade ≥ 3 TEAEs; and four had serious adverse events (SAEs). Two SAR445419-related SAEs (infusion-related reactions: both grade 2) were managed with supportive care. All participants experienced grade 3 anemia and grade 4 thrombocytopenia and neutropenia. Five deaths were reported, all due to disease progression, none related to SAR445419. No clinical responses were observed. CONCLUSIONS: This study demonstrated the overall safety of off-the-shelf ex vivo expanded allogeneic NK cells in patients with R/R AML. The successful manufacturing and distribution support the feasibility of donor-derived off-the-shelf NK cells in a clinical setting. Further investigations are required to improve the clinical efficiency of NK cells.
12 Apr 2026
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