Systematic preclinical evaluation of CD33-directed chimeric antigen receptor T cell immunotherapy for acute myeloid leukemia defines optimized construct design

J Immunother Cancer. 2021 Sep;9(9):e003149. doi: 10.1136/jitc-2021-003149.

Abstract

Background: Successful development of chimeric antigen receptor (CAR) T cell immunotherapy for children and adults with relapsed/refractory acute myeloid leukemia (AML) is highly desired given their poor clinical prognosis and frequent inability to achieve cure with conventional chemotherapy. Initial experiences with CD19 CAR T cell immunotherapy for patients with B-cell malignancies highlighted the critical impact of intracellular costimulatory domain selection (CD28 vs 4-1BB (CD137)) on CAR T cell expansion and in vivo persistence that may impact clinical outcomes. However, the impact of costimulatory domains on the efficacy of myeloid antigen-directed CAR T cell immunotherapy remains unknown.

Methods: In this preclinical study, we developed six CAR constructs targeting CD33, a highly expressed and validated AML target, comprised of one of three single-chain variable fragments with CD3ζ and either CD28 or 4-1BB costimulatory domains. We systematically compared the preclinical in vitro and in vivo efficacy of T cells lentivirally transduced with CD33 CAR constructs (CD33CARTs) against human AML.

Results: We observed potent in vitro cytokine production and cytotoxicity of CD33CARTs incubated with human CD33+ AML cell lines, as well as robust in vivo antileukemia activity in cell line and childhood AML patient-derived xenograft (PDX) models. Gemtuzumab-based CD33CARTs were unexpectedly toxic in vivo in animal models despite observed in vitro anti-leukemia activity. CD28-based CD33CARTs consistently induced more robust inhibition of leukemia proliferation in AML cell line and PDX models than did 4-1BB-based CD33CARTs. A 'best-in-class' lintuzumab-CD28/CD3ζ CAR construct was thus selected for clinical translation.

Conclusions: CD33 is a critical antigen for potential immunotherapeutic targeting in patients with AML. Based on this rigorous preclinical evaluation, our validated clinical grade lintuzumab-CD28/CD3ζ CD33CART immunotherapy is now under evaluation in a first-in-child/first-in-human phase 1 clinical trial for children and adolescents/young adults with relapsed/refractory AML.

Trial registration number: clinicaltrials.gov; NCT03971799.

Keywords: adoptive; chimeric antigen; hematologic neoplasms; immunotherapy; pediatrics; receptors; translational medical research.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Female
  • Humans
  • Immunotherapy, Adoptive / methods*
  • Leukemia, Myeloid, Acute / drug therapy*
  • Male
  • Mice
  • Receptors, Chimeric Antigen / metabolism*
  • Sialic Acid Binding Ig-like Lectin 3 / metabolism*
  • T-Lymphocytes / immunology*

Substances

  • Receptors, Chimeric Antigen
  • Sialic Acid Binding Ig-like Lectin 3

Associated data

  • ClinicalTrials.gov/NCT03971799