Investigating venom toxins as a therapeutic option for precursor B-cell acute lymphoblastic leukaemia (pre-B ALL)

Abstract

Precursor B-cell acute lymphoblastic leukaemia (pre-B ALL) is a haematological malignancy characterised by immature proliferation of B-cell lineage blasts. Current standard of care treatment for pre-B ALL involves multi-drug regimens of chemotherapy agents which despite high curative rates are often poorly tolerated by patients, inducing off-target side effects. To address this unmet clinical need, this project has identified for the first time a novel anticancer agent comprised of three phospholipase A2 (PLA2) enzymes. The compound, denominated PA-PLA2, was purified from Pseudechis australis snake venom using Reverse-Phase High Performance Liquid Chromatography, and validated by matrix assisted laser desorption ionisation-time of flight mass spectrometry and sequencing. Using a combination of cell-based functional assays and flow cytometry, PA-PLA2 was identified to induce caspase-independent necrotic cell death in two pre-B ALL cell lines representative of paediatric (Reh) and adult (SD-1) disease. Employing RNA-sequencing, protein- and phospho-proteomics analysis with time course Western blotting, elucidated PA-PLA2's mechanism of action to be RIPK1 and Akt dependent, inducing necroptosis in Reh cells and stunted cell cycle progression via Akt/p27Kip1 signalling in SD-1 cells. Importantly, PA-PLA2 treatment had minimal effects on the cell viability of a range of normal, peripheral blood and bone marrow-derived stem cells obtained from patient samples, with assays in donor citrated whole blood samples demonstrating PA-PLA2 to be non-haemolytic. Finally, by using a custom panel of 48 compounds, PA-PLA2 was identified to act synergistically in combination with the pre-B ALL induction phase chemotherapy agents, Cytarabine and Idarubicin.

Collectively, the findings from this project support the future use of snake venom toxins in pre-B ALL treatment. The identification, validation and characterisation of PA-PLA2 represents a platform for future investigations using animal venoms as natural sources for therapeutic agents, with further clinical investigation in more clinically relevant models needed to translate this thesis' findings.

Thesis is embargoed until 31 December 2026.

Date of Award	Dec 2023
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Karen McCloskey (Supervisor) & Ken Mills (Supervisor)