Drug resistance in mantle cell lymphoma (MCL) is highly dependent on BCR signaling and the microenvironment. Here, Simon Rule, MD, of Plymouth University, Plymouth, UK, discusses the OAsIs Phase I trial (NCT02558816), which was designed to assess the safety, tolerability and efficacy of ibrutinib/obinutuzumab, and ibrutinib plus obinutuzumab/venetoclax, with hopes to tackle this resistance in relapsed/refractory MCL. Speaking from the American Society of Hematology (ASH) 2018 Annual Meeting and Exposition in San Diego, CA, Prof. Rule reveals that as well as having no dose-limiting toxicities, treatment was well tolerated and provided a high level of disease control.