AZD4320 Is a Novel and Potent BCL-2/XL Dual Inhibitor in Targeting Aggressive Mantle Cell Lymphoma
Authors: Li Yijing , Liu Yang , McIntosh Joseph , Jordan Alexa A , Leeming Angela , Andersen Courtney L , Cidado Justin , Jiang Vivian Changying , Wang Michael 
Published: November 2020

Introduction: Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin's lymphoma. It is an incurable disease with frequent relapse from chemotherapies, targeted therapies, and cell therapies. Dysregulated expression of BCL-2 family members resulting in enhanced cell survival frequently occurs in many cancer types and often contributes to the development of therapeutic resistance. The BCL-2 inhibitor venetoclax has been shown to be effective in treating refractory/relapsed MCL patients. However, resistance often occurs and one of the underlying mechanisms of this resistance is the increased expression of other anti-apoptotic BCL-2 family members, such as BCL-XL and MCL-1. In this study, we assessed the in vitro and in vivo efficacy of a novel and highly potent BCL-2/XL dual inhibitor AZD4320 in preclinical models.
Methods: Cell viability assay was tested after 72-hour treatment with AZD4320 in a panel of ibrutinib/venetoclax-sensitive and -resistant MCL cell lines by CellTiter-Glo (Promega). The assay was also done after a 24-hour treatment in primary PDX cells. Cell apoptosis assay was performed to determine if AZD4320 induces cell apoptosis in MCL cell lines. Furthermore, the in vivo efficacy of AZD4320 was assessed in a CAR-T resistant MCL patient-derived xenograft (PDX) model.
Results: AZD4320 significantly inhibited cell proliferation in all tested MCL cell lines, including both ibrutinib/venetoclax-sensitive and -resistant cell lines. It had an IC50 value at a low nanomolar range between 0.59 nM to 18 nM. Consistently, AZD4320 was effective in targeting primary PDX cells ex vivo. AZD4320 induced cell apoptosis in a dose-dependent manner. AZD0466, the nanomedicine formulation of AZD4320 (30mg/kg, weekly, IV), dramatically inhibited tumor growth and prolonged mouse survival in an ibrutinib-CAR-T dual-resistant PDX mouse model. All mice tolerated the treatment dose without any body weight loss.
Conclusion: The novel BCL-2/XL dual inhibitor AZD4320 demonstrated excellent anti-MCL activity in both ibrutinib/venetoclax-sensitive and -resistant MCL cells in vitro. This was further validated in vivo in a ibrutinib-CAR-T dual-resistant PDX model. These findings provide evidence that dual targeting of BCL-2 and BCL-XL by AZD4320 is promising as it may overcome therapeutic resistance in relapsed/refractory MCL.

Disclosures
Andersen: AstraZeneca: Current Employment, Current equity holder in publicly-traded company. Cidado:AstraZeneca: Current Employment, Current equity holder in publicly-traded company. Wang:OMI: Honoraria, Other: Travel, accommodation, expenses; Nobel Insights: Consultancy; Loxo Oncology: Consultancy, Research Funding; Celgene: Consultancy, Other: Travel, accommodation, expenses, Research Funding; Kite Pharma: Consultancy, Other: Travel, accommodation, expenses, Research Funding; OncLive: Honoraria; Lu Daopei Medical Group: Honoraria; Acerta Pharma: Research Funding; VelosBio: Research Funding; BioInvent: Research Funding; Juno: Consultancy, Research Funding; Dava Oncology: Honoraria; Verastem: Research Funding; Molecular Templates: Research Funding; Oncternal: Consultancy, Research Funding; Pulse Biosciences: Consultancy; AstraZeneca: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Beijing Medical Award Foundation: Honoraria; Pharmacyclics: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; MoreHealth: Consultancy; Guidepoint Global: Consultancy; Targeted Oncology: Honoraria; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; InnoCare: Consultancy.