Characterization of a Novel FLT3 BiTE Molecule for the Treatment of Acute Myeloid Leukemia.
Bettina BrauchleRebecca L GoldsteinChristine M KarbowskiAnja HennChi-Ming LiVeit L BückleinChristina KrupkaMichael C BoylePriya KoppikarSascha HaubnerJoachim WahlChristoph DahlhoffTobias RaumMatthew J RardinChristine SastriDan A RockMichael von Bergwelt-BaildonBrendon FrankKlaus H MetzelerRyan CaseMatthias FriedrichMercedesz BalazsKarsten SpiekermannAngela CoxonMarion SubkleweTara ArvedsonPublished in: Molecular cancer therapeutics (2020)
Despite advances in the treatment of acute myeloid leukemia (AML), novel therapies are needed to induce deeper and more durable clinical response. Bispecific T-cell Engager (BiTE) molecules, which redirect patient T cells to lyse tumor cells, are a clinically validated modality for hematologic malignancies. Due to broad AML expression and limited normal tissue expression, fms-related tyrosine kinase 3 (FLT3) is proposed to be an optimal BiTE molecule target. Expression profiling of FLT3 was performed in primary AML patient samples and normal hematopoietic cells and nonhematopoietic tissues. Two novel FLT3 BiTE molecules, one with a half-life extending (HLE) Fc moiety and one without, were assessed for T-cell-dependent cellular cytotoxicity (TDCC) of FLT3-positive cell lines in vitro, in vivo, and ex vivo FLT3 protein was detected on the surface of most primary AML bulk and leukemic stem cells but only a fraction of normal hematopoietic stem and progenitor cells. FLT3 protein detected in nonhematopoietic cells was cytoplasmic. FLT3 BiTE molecules induced TDCC of FLT3-positive cells in vitro, reduced tumor growth and increased survival in AML mouse models in vivo Both molecules exhibited reproducible pharmacokinetic and pharmacodynamic profiles in cynomolgus monkeys in vivo, including elimination of FLT3-positive cells in blood and bone marrow. In ex vivo cultures of primary AML samples, patient T cells induced TDCC of FLT3-positive target cells. Combination with PD-1 blockade increased BiTE activity. These data support the clinical development of an FLT3 targeting BiTE molecule for the treatment of AML.
Keyphrases
- acute myeloid leukemia
- tyrosine kinase
- induced apoptosis
- allogeneic hematopoietic stem cell transplantation
- cell cycle arrest
- stem cells
- bone marrow
- signaling pathway
- epidermal growth factor receptor
- poor prognosis
- mesenchymal stem cells
- gene expression
- cell death
- drug delivery
- dna methylation
- cell proliferation
- big data
- diabetic rats
- binding protein
- transcription factor
- stress induced
- pi k akt
- free survival