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Blakemore, S. J.

Publications and source records attributed to Blakemore, S. J..

3 recordsLinked to original sources

Focal adhesion pathway inhibition is the central axis of macrophage phenotypic responses to monoclonal antibody therapy in aggressive lymphoma via high-throughput screening and high-content imaging

High-grade B-cell lymphoma (HGBCL) frequently arises as a refractory or relapsed state of diffuse large B-cell lymphoma (DLBCL) and is associated with poor outcomes due to multi-drug resistance and hallmark oncogenic translocations. To identify novel therapeutic strategies, we developed a dual high-throughput screening (HTS) and high-content imaging (HCI) macrophage-tumour co-culture platform that quantifies antibody-dependent and antibody-independent cellular phagocytosis (ADCP/AICP) across a 1,241-compound library. Using GFP+ HGBCL cells and mCherry+ macrophages, we validated our methodology through time-resolved phenotypic profiling, Euclidean distance-based analysis, and hit compound prioritisation. Pathway interrogation revealed focal adhesion as a central hub of macrophage phenotypic modulation, highlighting focal adhesion kinase (FAK/PTK2) as a candidate therapeutic target. Pharmacological inhibition with PF-562271 enhanced phagocytic activity, altered macrophage morphology, and synergised with anti-CD20 monoclonal antibodies in vitro and ex vivo. In vivo, Rituximab plus PF-562271 significantly reduced lymphoma burden and prolonged survival in xenograft models. Collectively, our work demonstrates that HTS/HCI-driven phenotypic profiling of tumour-associated macrophages can uncover actionable therapeutic combinations and nominates FAK inhibition as a promising strategy to potentiate antibody immunotherapy in HGBCL.

cell biology↗

Pentose Phosphate Pathway Inhibition activates Macrophages towards phagocytic Lymphoma Cell Clearance

Macrophages in the B-cell lymphoma microenvironment represent a functional node in progression and therapeutic response. We assessed metabolic regulation of macrophages in the context of therapeutic antibody-mediated phagocytosis. Pentose phosphate pathway (PPP) inhibition by specific compounds and shRNA targeting induced increased phagocytic lymphoma cell clearance. Moreover, macrophages provided decreased support for survival of lymphoma cells. PPP inhibition induced metabolic activation, cytoskeletal re-modelling and pro-inflammatory polarization of macrophages. A link between PPP and immune regulation was identified as mechanism of macrophage repolarization. Inhibition of the PPP causes suppression of glycogen synthesis and subsequent modulation of the immune modulatory UDPG-Stat1-Irg1-Itaconate axis. PPP inhibition rewired macrophage maturation and activation in vivo. Addition of the PPP inhibitor S3 to antibody therapy achieved significantly prolonged overall survival in an aggressive B-cell lymphoma mouse model. We hypothesize the PPP as key regulator and targetable modulator of macrophage activity in lymphoma to improve efficacy of immunotherapies. HighlightsO_LIMacrophage-mediated lymphoma cell phagocytosis is increased by pentose phosphate pathway (PPP) inhibition as an immune regulatory switch for macrophage function and polarization C_LIO_LIPPP inhibition is linked to decreased glycogen synthesis and subsequent modulation of the UDPG-Stat1-Irg1-Itaconate axis C_LIO_LIPPP inhibition is tolerable in vivo and facilitates therapeutic targeting of B-cell lymphoma C_LI

cancer biology↗

Loss of TP53 mediates suppression of Macrophage Effector Function via Extracellular Vesicles and PDL1 towards Resistance against Chemoimmunotherapy in B-cell malignancies

Chemoimmunotherapy (CIT) is the standard of care in B-cell malignancies. It is relying on synergistic effects of alkylating chemotherapy and monoclonal antibodies via secretory crosstalk with effector macrophages. Here, we observed that loss of p53 function mediates resistance to CIT by suppressing macrophage phagocytic function. Loss of p53 leads to an upregulation of PDL1 and an increased formation of extracellular vesicles (EVs). EVs directly inhibit macrophage phagocytosis by PDL1 surface expression. Suppression of phagocytic function by lymphoma cell-derived EVs could be abrogated by pre-incubation of EVs with anti-PDL1 antibodies, CRISPR-KO of PDL1 and abrogation of EV formation by RAB27A-KO in lymphoma cells. Immune checkpoint inhibition represents a viable strategy to overcome EV-mediated resistance to chemoimmunotherapy in lymphoma. SignificanceLoss of TP53 mediates cell autonomous resistance to genotoxic chemotherapy, moreover non-cell autonomous effects may cause therapy resistance mediated by the tumor microenvironment. We identify a TP53-dependent mechanism that mediates resistance to synergistic chemoimmunotherapy by increasing formation of EVs and expression of the PDL1 immune checkpoint. PDL1 on EVs is directly responsible for macrophage suppression, preventing the exertion of the essential effector function of antibody-dependent cellular phagocytosis. This novel mechanism of resistance is in turn targetable by PDL1 checkpoint inhibition. Enhanced EV-release and immune checkpoint expression in lymphoma are novel mechanisms of macrophage modulation in the lymphoma microenvironment. We provide a novel principle of resistance to chemoimmunotherapy (CIT) representing of immediate relevance to treatment of refractory B-cell lymphoma. HighlightsO_LILoss of TP53 in B-cell lymphoma induces resistance towards chemoimmunotherapy (CIT) by inhibition of macrophage effector function through PDL1 upregulation C_LIO_LILoss of TP53 increases formation of extracellular vesicles (EVs) carrying PDL1 C_LIO_LIEVs inhibit antibody-mediated cellular phagocytosis (ADCP), a key macrophage effector function in CIT C_LIO_LITargeting PDL1 on EVs with immune checkpoint inhibitors overcomes TP53-mediated resistance to CIT C_LI

cell biology↗