PEGCRISANTASPASE AND VENETOCLAX COMBINATION IS HIGHLY EFFECTIVE AGAINST ACUTE MYELOID LEUKEMIA (AML), MECHANISTICALLY DRIVEN SYNERGISM BETWEEN GLUTAMINE DEPLETION AND BCL-2 INHIBITION
Author(s): ,
Ashkan Emadi
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Ronald Gartenhaus
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Binny Bhandary
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Hannah Kaizer
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Elizabeth Chang
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Eun Yong Choi
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Brandon Carter-Cooper
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
,
Amol Shetty
Affiliations:
Institute for Genome Sciences,University of Maryland,Baltimore,United States
,
Anup Mahurkar
Affiliations:
Institute for Genome Sciences,University of Maryland,Baltimore,United States
,
Bandish Kapadia
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
Rena Lapidus
Affiliations:
University of Maryland Greenebaum Comprehensive Cancer Center,Baltimore,United States
EHA Library. Emadi A. Jun 15, 2019; 267417; S834
Dr. Ashkan Emadi
Dr. Ashkan Emadi
Contributions
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Abstract

Abstract: S834

Type: Oral Presentation

Presentation during EHA24: On Saturday, June 15, 2019 from 11:45 - 12:00

Location: Forum Hall

Background
We reported that Erwinaze could effectively deplete plasma glutamine (Gln) to undetectable levels in patients (pts) with relapsed/refractory (R/R) AML and these pts had higher probability of clinical response. We hypothesized that Gln depletion (pegcrisantaspase, a recombinant pegylated Erwinia crisantaspase, PegC [Jazz Pharmaceuticals]) leads to activation of mitochondrial apoptotic pathways and synergizes with Bcl-2 inhibition (venetoclax, Ven). In vitro, we demonstrated that anti-AML activity of Ven was potentiated 10-44 fold by PegC; presence of PegC (0.01 IU/mL) decreased Ven’s IC50 (5.3→0.12 µM in MOLM-14 & 7.5→0.76 µM in MonoMac-6 cells). Ven-PegC demonstrated synergy in killing AML cells. Here, we report the mechanism of action (MOA), and in vivo safety and efficacy of Ven-PegC in AML.

Aims
(1) To determine toxicity profile of Ven-PegC in mice (2) To analyze effect of Ven-PegC on plasma Gln in vivo (3) To determine efficacy of Ven-PegC in orthotopic pt-derived xenograft (PDX), and (4) To assess changes in the transcriptome/translatome of AML cells treated with Ven-PegC.

Methods
Toxicity profile of Ven-PegC was investigated in immune competent (CD1) and incompetent (NRG/NSG) mice. To measure pharmacodynamic (PD) effect of PegC, NSG mice were dosed once IV at 3 different doses [125, 250 and 500 IU/kg (n=4 mice/dose)]. We euthanized 2 mice on days 3 and 10 and measured plasma amino acids by LCMS. Efficacy of Ven-PegC was assessed in an AML pt-derived xenograft model (AML-45) that expresses luciferase. We injected 1x106 AML-45-luc cells IV into NRG mice, and after engraftment mice were treated with vehicle, Ven (75 mg/kg, PO, 5x/week), PegC (200 IU/kg, IV, 1x/week), or Ven-PegC for 2 weeks (wks), 1 wk off, then 2 more wks. Mice were imaged weekly and survival monitored. For MOA, MOLM-14 cells were treated with each agent alone and combined followed by RNA isolation, RNA-seq and transcriptome analysis. For translatome, cells were treated similarly and subjected to western blotting, cap enrichment and polysomal fractionation.

Results
For safety, Ven-PegC resulted in mild weight loss with full recovery at PD active doses. Amylase, lipase, creatinine, and transaminases were unchanged after 3 wks of Ven-PegC treatment. Ven-PegC induced myelosuppression as expected (7.4±1.0x103/µL control vs 1.9±0.3x103/µL combination, p<0.003). For PD, asparagine was not detectable on days 3 & 10 post dosing. No plasma Gln was detected on day 3 and on day 10 was undetectable at the highest dose. For efficacy, Ven-PegC significantly lowered leukemia burden compared to monotherapies (p<0.03). On Day 36, AML was virtually undetectable in mice treated with Ven-PegC (Fig. 1A-1B). For MOA, immunoblot analysis showed decreased phosphorylation of mTOR substrates (p70S6K & 4E-BP1) with Ven-PegC. A significant decrease in cap driven translation complexes and in eIF4E phosphorylation at Ser-209 followed by enhanced interaction with 4E-BP1 were observed with Ven-PegC (Fig. 1C). Transcriptome analysis showed differential gene expression pattern between groups (RT-qPCR validated; Fig. 1D). p90RSK, a key gene in ribosomal biogenesis and cell proliferation, was reduced upon Ven-PegC treatment in MOLM-14 transcriptome profiling (RNA-qPCR/immunoblot analysis confirmed). Analysis of altered translational profile is ongoing.

Conclusion
Ven-PegC is a mechanistically-driven, highly active treatment against AML in the PDX model. Ven-PegC appears to broadly regulate the ribosomal biosynthetic pathway, a major driver for chemo-resistance. The Phase 1 clinical trial in pts with R/R AML is planned.

Session topic: 3. Acute myeloid leukemia - Biology & Translational Research

Keyword(s): AML, BCL2

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