Dual BTK/SYK inhibition with CG-806 (luxeptinib) disrupts B-cell receptor and Bcl-2 signaling networks in mantle cell lymphoma

Elana Thieme,Stephen E Kurtz,Shannon K Mcweeney,Tingting Liu,Vi Lam,Jeffrey W Tyner,Tamilla Nechiporuk,Nur Bruss,Daniel Bottomly,Carly Roleder,Xiaoguang Wang,Alexey V Danilov,Olga V Danilova,Geoffrey Shouse

doi:10.1038/s41419-022-04684-1

Abstract

Aberrant B-cell receptor (BCR) signaling is a key driver in lymphoid malignancies. Bruton tyrosine kinase (BTK) inhibitors that disrupt BCR signaling have received regulatory approvals in therapy of mantle cell lymphoma (MCL). However, responses are incomplete and patients who experience BTK inhibitor therapy failure have dire outcomes. CG-806 (luxeptinib) is a dual BTK/SYK inhibitor in clinical development in hematologic malignancies. Here we investigated the pre-clinical activity of CG-806 in MCL. In vitro treatment with CG-806 thwarted survival of MCL cell lines and patient-derived MCL cells in a dose-dependent manner. CG-806 blocked BTK and SYK activation and abrogated BCR signaling. Contrary to ibrutinib, CG-806 downmodulated the anti-apoptotic proteins Mcl-1 and Bcl-xL, abrogated survival of ibrutinib-resistant MCL cell lines, and partially reversed the pro-survival effects of stromal microenvironment-mimicking conditions in primary MCL cells. Dual BTK/SYK inhibition led to mitochondrial membrane depolarization accompanied by mitophagy and metabolic reprogramming toward glycolysis. In vivo studies of CG-806 demonstrated improved survival in one of the two tested aggressive MCL PDX models. While suppression of the anti-apoptotic Bcl-2 family proteins and NFκB signaling correlated with in vivo drug sensitivity, OxPhos and MYC transcriptional programs were upregulated in the resistant model following treatment with CG-806. BAX and NFKBIA were implicated in susceptibility to CG-806 in a whole-genome CRISPR-Cas9 library screen (in a diffuse large B-cell lymphoma cell line). A high-throughput in vitro functional drug screen demonstrated synergy between CG-806 and Bcl-2 inhibitors. In sum, dual BTK/SYK inhibitor CG-806 disrupts BCR signaling and induces metabolic reprogramming and apoptosis in MCL. The Bcl-2 network is a key mediator of sensitivity to CG-806 and combined targeting of Bcl-2 demonstrates synergy with CG-806 warranting continued exploration in lymphoid malignancies.

Highlights

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin’s lymphoma (NHL) manifesting rearrangement of cyclin D1
MCL cell lines treated with CG-806 exhibited a decrease in phosphorylation of the proximal BCRassociated kinases spleen tyrosine kinase (SYK) and Bruton tyrosine kinase (BTK), which was sustained for 24 h and was more pronounced compared to ibrutinib (Fig. 1C, D and Supplementary Fig. 2)
Since dual BTK/SYK inhibition altered the expression of Mcl-1 and Bcl-xL, we investigated the effects of CG-806 on mitochondrial dynamics

Summary

Introduction

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin’s lymphoma (NHL) manifesting rearrangement of cyclin D1. MCL is characterized by significant genetic heterogeneity and typically follows an aggressive clinical course [1, 2]. Chronic active B-cell receptor (BCR) signaling has been implicated in lymphomagenesis [3]. BCR crosslinking promotes interaction between SRC family kinases (e.g., LYN) and CD79A/B and thereby induces activation of spleen tyrosine kinase (SYK). SYK is an integral BCR-signaling kinase that recruits Bruton tyrosine kinase (BTK) and adaptor molecules triggering divergent downstream events that lead to propagation of AKT, MAPK, and NFκB signaling and upregulation of the Bcl-2 family proteins [4]. Activation of the BCR-associated kinases SYK and BTK plays a pivotal role in regulation of survival, proliferation, and homing of malignant B cells

Methods

Results

Conclusion