Activity of the novel BTK inhibitor TG-1701 is associated with the disruption of the Ikaros signaling pathway in responder B-NHL patients and with sensitization to anti-CD20 therapy in B-NHL xenografts

ABSTRACT: Covalent Bruton's tyrosine kinase inhibitors (BTKis) have transformed the treatment of B-cell non-Hodgkin lymphoma (B-NHL), including chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), but their activity has been limited by off-target toxicity and acquired drug resistance. TG-1701 is a novel irreversible and highly specific BTKi being presently under study in a phase 1 clinical trial in patients with relapsed/refractory B-NHL alone and in combination with ublituximab, a CD20 antibody, and umbralisib, a dual PI3Kδ and CK1ε inhibitor. Here we show, for the first time that phosphoproteomic analysis of CLL patients receiving a BTKi (TG-1701) led to a non-supervised clustering that matched the clinical outcomes and separated a group of “responders” from a group of “non-responders”. This clustering was based on a selected list of 96 phosphosites, with Ikaros-Ser442/445 phosphorylation as a potential marker for TG-1701 efficacy. RNA-seq analysis followed by qPCR and western blot validation further revealed that TG-1701 treatment blunted the Ikaros gene signature only in responder patients, as well as in BTKi-sensitive, but not BTKi-insensitive, B-NHL cell lines and xenografts. Importantly, and in contrast with ibrutinib, TG-1701 did not impair FcγR-driven antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP) triggered by the anti-CD20 antibodies rituximab and ublituximab in a multicellular MCL co-culture system. In addition, TG-1701 cooperated with ublituximab coupled to umbralisib (also referred as the U2 regimen) in reducing the tumor growth in both ibrutinib-sensitive and ibrutinib-insensitive mouse models of MCL. Altogether, these data validate phosphoproteomic as a broken thread to omics analysis in the clinic and support the use of TG-1701-U2 combination in R/R B-NHL patients, irrespective of prior response to ibrutinib.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): B Cell, Peripheral Blood Mononuclear Cell

DISEASE(S): Chronic Lymphocytic Leukemia

SUBMITTER: Joan Josep Bech-Serra  

LAB HEAD: Gael Roue

PROVIDER: PXD023231 | Pride | 2021-09-22

REPOSITORIES: Pride