Development of A Chimeric Antigen Receptor Targeting C-Type Lectin-Like Molecule-1 for Human Acute Myeloid Leukemia

Eduardo Laborda,Xinxin Wang,Magdalena Mazagova,Chan Kim,Herlinda Quirino,David Rodgers,Sida Shao,Ashley Woods,Peter Schultz,Eric Hampton,Travis Young

doi:10.3390/ijms18112259

Abstract

The treatment of patients with acute myeloid leukemia (AML) with targeted immunotherapy is challenged by the heterogeneity of the disease and a lack of tumor-exclusive antigens. Conventional immunotherapy targets for AML such as CD33 and CD123 have been proposed as targets for chimeric antigen receptor (CAR)-engineered T-cells (CAR-T-cells), a therapy that has been highly successful in the treatment of B-cell leukemia and lymphoma. However, CD33 and CD123 are present on hematopoietic stem cells, and targeting with CAR-T-cells has the potential to elicit long-term myelosuppression. C-type lectin-like molecule-1 (CLL1 or CLEC12A) is a myeloid lineage antigen that is expressed by malignant cells in more than 90% of AML patients. CLL1 is not expressed by healthy Hematopoietic Stem Cells (HSCs), and is therefore a promising target for CAR-T-cell therapy. Here, we describe the development and optimization of an anti-CLL1 CAR-T-cell with potent activity on both AML cell lines and primary patient-derived AML blasts in vitro while sparing healthy HSCs. Furthermore, in a disseminated mouse xenograft model using the CLL1-positive HL60 cell line, these CAR-T-cells completely eradicated tumor, thus supporting CLL1 as a promising target for CAR-T-cells to treat AML while limiting myelosuppressive toxicity.

Highlights

acute myeloid leukemia (AML) is the most common type of acute leukemia in adults
The high heterogeneity of AML calls for the development of chimeric antigen receptor (CAR)-T-cells that will enable the treatment of a broader patient population with reduced risk of long-term adverse effects
We designed and optimized a CAR-T-cell targeting the type II transmembrane glycoprotein, CLL1, a target recently used for cancer immunotherapies [11,12] that is expressed in 92% of AML patients [13]

Summary

Introduction

AML is the most common type of acute leukemia in adults. Established first line and consolidation chemotherapy is effective for 70–80% of patients; with a five-year survival rate of 26%, the development of new therapies is urgently required [1]. The high heterogeneity of AML calls for the development of CAR-T-cells that will enable the treatment of a broader patient population with reduced risk of long-term adverse effects. We designed and optimized a CAR-T-cell targeting the type II transmembrane glycoprotein, CLL1, a target recently used for cancer immunotherapies [11,12] that is expressed in 92% of AML patients [13]. CLL1 is present on a small population of chemotherapy-resistant leukemic stem cells hypothesized to be responsible for relapse [14,15], making it an ideal target antigen for the treatment of AML patients with CAR-T-cells [12,13,15]

Results and Discussion

Cells and Human Derived Samples

In Vitro Assays

Xenograft Model