ME-401 is an oral, once-daily, selective PI3Kδ inhibitor, part of a signaling pathway in cells that can become hyperactive leading to tumor growth and resistance to chemotherapy.

In preclinical studies, ME-401 reached its target site (PI3Kδ) and bound to it more tightly and longer than idelalisib, another PI3Kδ inhibitor. ME-401 bound to its target tightly for ~ 5 h compared with ~ 2 min for idelalisib.

Oral ME-401 is well absorbed and distributed throughout the body in animal studies with concentrations in key sites for lymphoma including lymph, plasma, lymphoma tumor, and brain tissue.