Development of novel targeted drug formulations for the treatment of haematological malignancies

Abstract

Leukaemia has the highest incidence and mortality among haematological malignancies and is the most common childhood cancer. Despite advancements, current therapies largely rely on non-targeted chemotherapy, associated with severe side effects and limited efficacy. Nanoparticles (NPs) have shown promise in the treatment of acute myeloid leukaemia (AML) and acute lymphocytic leukaemia (ALL), with the approval of Vyxeos®, and Marqibo®, which minimised systemic toxicities and improved drug pharmacokinetics. However, antibody-targeted formulations offer even greater potential due to their high specificity. While antibody-conjugated NPs (ACNPs) are lacking clinical approval, antibody-drug conjugates (ADCs) have seen an upsurge with 13 clinically approved constructs, including Gemtuzumab ozogamicin and Inotuzumab ozogamicin, for AML and ALL, respectively. Therefore, this work proposes developing innovative targeted drug formulations for acute leukaemia using nanoparticle and antibody-based approaches. Initially, the synergistic pairing of ABT-737 and Purvalanol A was explored and validated in paediatric AML cell models. Then, a poly (lactic-co-glycolic acid) (PLGA)-based nanoformulation was developed for their ratiometric co-delivery, to overcome limitations such as their very poor hydrophilicity and severe side effects. The resulting dual drug-loaded NP revealed optimal physicochemical characteristics and therapeutic efficacy, demonstrated by significantly enhanced apoptotic cell death. Gemtuzumab and its fragments were then employed as targeting moieties to develop CD33-targeted polymeric NPs (CD33 NPs), through maleimide-thiol coupling. CD33 NPs revealed specific and enhanced binding to CD33 and internalization in CD33-positive cells. Furthermore, CD33-targeted dual-loaded NPs retained desired physicochemical characteristics, and improved delivery of the entrapped payloads. Finally, different nanoparticle- and ADC-based formats were explored to harness the unique therapeutic potential of α-amanitin. While the extremely hydrophilic nature of α-amanitin raised numerous challenges for its nanoencapsulation, a highly homogeneous anti-CD19 α-amanitin-based ADC was successfully developed. This ADC showed targeting selectivity and picomolar toxicity in CD19-positive cell lines, achieving up to 4,200-fold higher effectiveness than the free drug in B-cell ALL models.

Thesis embargoed until 31st December 2029

Date of Award	Dec 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	EU Horizon 2020 Marie Sklodowska-Curie ITN Programme
Supervisor	Christopher Scott (Supervisor) & Karen McCloskey (Supervisor)