High-avidity cathepsin-G-specific CAR-T cells (CG1.CAR-T) demonstrate potent anti-leukemia effects without hematopoietic toxicity.
Background
Acute myeloid leukemia (AML) is the most aggressive and prevalent form of leukemia in adults, with current gold-standard treatments involving chemotherapy and hematopoietic stem cell transplantation. However, drug resistance is a frequent complication, and the genetic heterogeneity and lack of truly tumor-specific antigens in AML hinder the success of conventional immunotherapies. A significant challenge with CAR-T cells targeting myeloid-associated antigens is the potential for on-target, off-tumor toxicity, leading to depletion of normal myeloid progenitor cells. This study addresses this critical gap by developing a highly specific CAR-T cell therapy for AML that aims to spare healthy hematopoietic cells.
Study Design
Researchers developed a CAR specific for an HLA-A*02:01-restricted peptide of myeloid-restricted cathepsin-G, termed CG1.CAR. To boost functional avidity, CG1.CAR-T cells were engineered to co-express LCK and a duplicated CD3ζ chain. Antileukemia effects were tested in vitro and in vivo in AML patient-derived-xenotransplant (PDX) mouse models. Hematopoietic toxicity was assessed using colony assays and humanized mice. Mechanistically, LCK overexpression effects on transcription, mitochondrial mass, and respiratory capacity were investigated.
Results
Optimized CG1.CAR-T cells demonstrated functional recognition of the CG1 peptide at concentrations as low as 0.025 mM, indicating significantly enhanced avidity. These engineered cells displayed potent antileukemia effects both in vitro and in vivo within AML patient-derived-xenotransplant (PDX) mouse models, effectively reducing tumor burden. Crucially, the CG1.CAR-T cells did not induce hematopoietic toxicity in colony assays or in humanized mice, addressing a major safety concern for myeloid-targeted CAR-T therapies. > Mechanistically, LCK overexpression in CG1.CAR-T cells led to significant transcriptional modifications, characterized by the overexpression of mitochondrial-encoded electron transport chain components. These changes were directly correlated with an observed increase in mitochondrial mass and improved respiratory capacity, providing a clear biological basis for their enhanced functional avidity and antileukemia efficacy.
Key Findings
- Engineered CG1.CAR-T cells recognized the CG1 peptide at 0.025 mM.
- CG1.CAR-T cells showed antileukemia effects in AML PDX mouse models.
- CG1.CAR-T cells did not cause hematopoietic toxicity in
colony assaysor humanized mice. LCKoverexpression in CG1.CAR-T cells increased mitochondrial mass and respiratory capacity.- Transcriptional changes included overexpression of mitochondrial electron transport chain components.
Why It Matters
The development of highly specific CAR-T cells for Acute Myeloid Leukemia (AML) that spare healthy myeloid cells represents a critical advancement towards safer and more effective treatments. Current CAR-T approaches for AML often face on-target, off-tumor toxicity due to shared antigens, limiting their clinical utility. This research presents a novel strategy to overcome this by targeting an HLA-A*02:01-restricted peptide of cathepsin-G, minimizing damage to normal hematopoiesis. The engineering to boost functional avidity and mitochondrial function could inform future CAR-T cell design, potentially leading to more potent and durable responses in other cancers. These preclinical findings suggest a promising path toward a clinically translatable CG1.CAR-T therapy, potentially reducing the need for intensive chemotherapy or stem cell transplantation in some AML patients.
car-t cells
acute myeloid leukemia
aml
cathepsin-g
lck
immunotherapy