eprintid: 33929
rev_number: 13
eprint_status: archive
userid: 7691
dir: disk0/00/03/39/29
datestamp: 2023-11-07 10:05:30
lastmod: 2024-07-22 10:35:20
status_changed: 2023-11-07 10:05:30
type: doctoralThesis
metadata_visibility: show
creators_name: Narr, Andreas
title: Classification of acute myeloid leukemia as
a ferroptosis-sensitive malignancy suggesting the
development of arsenic trioxide mediated
ferroptosis-inducing combination therapies
divisions: i-140001
adv_faculty: af-14
abstract: Despite advancements in the treatment of acute myeloid leukemia (AML), the 5-year survival
rate of AML patients remains poor. The majority of patients face disease recurrence partly due
to acquired resistance against classical cell death programs. Therefore, exploiting alternative
forms of cell death, such as ferroptosis, may allow to design novel therapies to limit survival or
occurrence of such resistant AML clones.
Ferroptosis is a recently identified iron-dependent and non-apoptotic form of cell death. It is
characterized by an excessive ROS-induced peroxidation of poly-unsaturated fatty acids
(PUFAs) within cell membranes and its chemical induction has shown promising therapeutic
potential in multiple solid cancer entities. The work provided here aimed to investigate the role
of ferroptosis in AML and explore its therapeutic possibilities for the treatment of AML.
In this thesis, I first investigated the overall dependency of AML on ferroptosis-related genes
(FRGs) using publicly available data sets. Secondly, I evaluated the ferroptosis sensitivity of
various AML cell lines through chemical inhibition and genetic deletion of ferroptosis
regulators. With these insights, I demonstrated the essentiality of the master ferroptosis
suppressor GPX4 in AML cell lines in vitro as well as in vivo and revealed high sensitivity of
AML cell lines to chemical ferroptosis induction with Imidazole Ketone Erastin (IKE). In
addition, I described the prognostic value of several FRGs and generated a 7-gene ferroptosis
signature as a powerful predictor of patient survival.
By performing a comprehensive drug screen aimed at assessing the ferroptosis-inducing
capacity of the drugs, I identified arsenic trioxide (ATO) as a potent inducer of ferroptosis in
AML cells. Notably, the detailed characterization of the drug’s mechanism of action on the
RNA level using SLAM-Sequencing revealed the activity of the iron-metabolism gene HMOX1
as being essential for ATO-induced ferroptosis. Mechanistically, we showed that ATO directly
interacts with GPX4, one of the major ferroptosis-suppressive regulators, resulting in its
inhibition and degradation by the proteasomal system. These findings position ATO as a new
class II ferroptosis-inducing agent directly acting on GPX4, for which no clinically usable
inhibitor exists to date.
By performing targeted mass spectrometry and metabolite tracing experiments, we highlighted
the importance of glutaminolysis for glutathione (GSH) synthesis. I further demonstrated that
ATO treatment results in upregulation of metabolic pathways providing cysteine for GSH
synthesis; namely SLC7A11-mediated cystine-uptake and the transsulfuration pathway.
Chemical inhibition as well as genetic deletion of these pathways combined with ATO
treatment showed strong synergistic effects marking these pathways as new targetable
vulnerabilities in AML to enhance ATO-induced ferroptosis.
By combining these findings, I designed a novel triple combination therapy (ATO+
CB-839+PPG) targeting the glutaminolysis and transsulfuration pathways in combination with
ATO-mediated GPX4 inhibition and degradation. I demonstrated that the triple combination
therapy resulted in high efficacy in killing AML cell lines as well as primary AML patient
samples at diagnosis and relapse. Moreover, this triple combination therapy was effective in
venetoclax + azacytidine (VenAza) resistant AML cell lines, providing a potential means to
overcome VenAza resistance.
Moreover, I demonstrated that the ferroptosis inducers ATO and IKE synergize with VenAza
treatment, offering additional promising combination therapies.
In summary, the results in this thesis classify AML as one of the most ferroptosis-sensitive
cancer entities. Moreover, we revealed the ferroptosis-inducing capacity of ATO as a novel
GPX4 inhibitor and degrader. Detailed characterization of the drug’s mechanism on the genetic
and metabolic level enabled me to design new effective combination therapies exploiting newly
identified vulnerabilities in AML. These results provide a rational basis for a pre-clinical and
subsequent clinical evaluation of ferroptosis-inducing therapies in AML patients.
date: 2024
id_scheme: DOI
id_number: 10.11588/heidok.00033929
ppn_swb: 1895993679
own_urn: urn:nbn:de:bsz:16-heidok-339299
date_accepted: 2023-09-18
advisor: HASH(0x559e37cbfb80)
language: eng
bibsort: NARRANDREACLASSIFICA20230918
full_text_status: public
place_of_pub: Heidelberg
citation:   Narr, Andreas  (2024) Classification of acute myeloid leukemia as a ferroptosis-sensitive malignancy suggesting the development of arsenic trioxide mediated ferroptosis-inducing combination therapies.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/33929/1/Thesis_AndreasNarr_final.pdf