The complement receptor C3AR constitutes a novel therapeutic target in NPM1-mutated AML

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Mutated nucleophosmin 1 (NPM1) is the most frequent genetic alteration in acute myeloid leukemia (AML), present in about 30% of cases.
• Despite favorable risk stratification, NPM1-mutated AML patients often relapse, necessitating novel therapeutic strategies.
• Targeting specific cell surface proteins on NPM1-mutated AML cells could enable effective antibody-based treatments.

Purpose of the Study:

• To identify unique cell surface markers on NPM1-mutated AML cells for antibody-based therapy development.
• To evaluate complement receptor C3AR as a potential therapeutic target in NPM1-mutated AML.

Main Methods:

• An arrayed flow cytometry screen of 362 cell surface markers was performed.
• Comparison of cell surface protein expression between NPM1-mutated AML cells and normal bone marrow cells (CD34+ CD38-).
• Validation using flow cytometry, single-cell RNA sequencing, and xenotransplantation into immunodeficient mice.
• Assessment of antibody-mediated natural killer (NK) cell killing of primary AML cells ex vivo.

Main Results:

• Complement receptor C3AR was identified as specifically expressed on NPM1-mutated AML cells.
• Normal hematopoietic stem and progenitor cells showed no detectable C3AR expression.
• C3AR, in conjunction with GPR56, effectively distinguished leukemic stem cells (LSCs) in NPM1-mutated AML from normal hematopoietic stem cells.
• Stimulation of C3AR with its ligand C3a activated ERK1/2 and promoted AML cell survival.
• Antibodies targeting C3AR induced NK cell-mediated killing of primary AML cells ex vivo.

Conclusions:

• Complement receptor C3AR is a highly specific cell surface target on NPM1-mutated AML.
• C3AR expression defines the leukemic stem cell population in NPM1-mutated AML.
• C3AR represents a promising candidate for developing novel antibody-based therapies against NPM1-mutated AML.