Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) (MALT1)

The CARD11-BCL10-MALT1 (CBM) complex is a critical signaling signalosome that bridges cell surface antigen receptors, such as the B-cell receptor (BCR) and T-cell receptor (TCR), to the activation of the NF-kappaB pathway. MALT1 (Mucosa-associated lymphoid tissue lymphoma translocation protein 1) is the central effector of this complex, possessing both a scaffolding function and a unique paracaspase proteolytic activity. Upon antigen stimulation, MALT1 is recruited to the CBM complex where it undergoes dimerization and activation, subsequently cleaving several negative regulators of NF-kappaB (e.g., A20, CYLD) and other substrates (e.g., RelB, BCL10) to amplify and sustain immune signaling. Dysregulation of MALT1 is a key driver in various hematologic malignancies, most notably in mucosa-associated lymphoid tissue (MALT) lymphoma and the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), where constitutive MALT1 activity promotes tumor cell survival and proliferation. Beyond oncology, MALT1 signaling is implicated in autoimmune and inflammatory conditions like psoriasis and rheumatoid arthritis. Therapeutic targeting of MALT1 with small-molecule inhibitors, including allosteric and active-site binders, is currently being explored in clinical trials for relapsed or refractory B-cell lymphomas. However, because MALT1 is also essential for the development of regulatory T cells (Tregs), its chronic inhibition poses a risk of systemic immunosuppression and potential autoimmune complications.

Other names

MALT1Paracaspase-1PCASP1MLTMLT1CARD11-BCL10-MALT1 complexCBM complexCaspase-like protein

MALT1 inhibitors function by blocking the proteolytic activity of the paracaspase domain, either through active-site binding or allosteric modulation. This prevents the cleavage of key substrates such as A20, CYLD, and RelB, which normally serve to amplify and sustain NF-kappaB signaling, thereby inhibiting the survival and proliferation of malignant B-cells and the activation of inflammatory T-cells.