An updated patent review of MALT1 inhibitors (2021-present)

INTRODUCTION

MALT1 paracaspase acts as a molecular scaffold and a proteolytic enzyme in immune cells. MALT1 has emerged as a promising drug target for cancer therapy, and especially for targeting MALT1 in aggressive lymphomas. Drug discovery programs have yielded potent and selective MALT1 protease inhibitors. First-in-class MALT1 inhibitors have been moved to early clinical trials to evaluate safety and efficacy.

AREAS COVERED

This review will provide an update regarding the mode of action, the chemical space and therapeutic use of MALT1 inhibitors based on recent patents and the scientific literature (05/2021-12/2024).

EXPERT OPINION

Allosteric inhibition is the preferred mode of action to inhibit the MALT1 protease. Chemical advances largely focus on improving binding and inhibition in the allosteric site of MALT1. New composition of matter has been generated, but a clinical proof for the safety and efficacy of allosteric MALT1 inhibitors is still pending. We still lack potent and selective competitive or covalent MALT1 inhibitors, indicating the challenges with targeting the active site. Further, MALT1 protein degraders and MALT1 scaffolding inhibitors have been developed, which may have distinct inhibitory profiles compared to allosteric MALT1 protease inhibitors, but more potent and selective compounds are needed to judge the feasibility and usefulness of these approaches.

MALT1 Inhibitors and Degraders: Strategies for NF-κB-Driven Malignancies

Mucosa-associated lymphoid tissue protein 1 (MALT1), a cysteine protease and the sole paracaspase in humans, plays a pivotal role in the survival and proliferation of NF-κB-dependent malignant cancers, particularly MALT lymphoma and diffuse large B-cell lymphoma (DLBCL). Dysregulated MALT1 activity is implicated in various malignancies, highlighting its importance as a therapeutic target. This Perspective provides an overview of MALT1's structural and functional characteristics, summarizes recent advancements in small-molecule inhibitors and degraders targeting this protein, and discusses compound structures, structure-activity relationship (SAR) analyses, and biological activities. We aim to inform future research efforts to enhance the activity, selectivity, and pharmacological properties of MALT1-targeting compounds, establishing a foundational framework for drug development in this critical area of cancer therapy.

Anticancer Activity of Lesbicoumestan in Jurkat Cells via Inhibition of Oxidative Stress-Mediated Apoptosis and MALT1 Protease

This study explores the potential anticancer effects of lesbicoumestan from Lespedeza bicolor against human leukemia cancer cells. Flow cytometry and fluorescence microscopy were used to investigate antiproliferative effects. The degradation of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) was evaluated using immunoprecipitation, Western blotting, and confocal microscopy. Apoptosis was investigated using three-dimensional (3D) Jurkat cell resistance models. Lesbicoumestan induced potent mitochondrial depolarization on the Jurkat cells via upregulated expression levels of mitochondrial reactive oxygen species. Furthermore, the underlying apoptotic mechanisms of lesbicoumestan through the MALT1/NF-κB pathway were comprehensively elucidated. The analysis showed that lesbicoumestan significantly induced MALT1 degradation, which led to the inhibition of the NF-κB pathway. In addition, molecular docking results illustrate how lesbicoumestan could effectively bind with MALT1 protease at the latter's active pocket. Similar to traditional 2D cultures, apoptosis was markedly induced upon lesbicoumestan treatment in 3D Jurkat cell resistance models. Our data support the hypothesis that lesbicoumestan is a novel inhibitor of MALT1, as it exhibited potent antiapoptotic effects in Jurkat cells.