This clinical trial is for men and women age 18 and older with mantle cell lymphoma (MCL) to check efficacy and safety of the combination of acalabrutinib, lenalidomide and rituximab (ALR) in previously untreated mantle cell lymphoma. 

Mantle cell lymphoma is a type of cancer that the body makes abnormal B-cells (white blood cells) responsible for fighting infections. Mantle cell lymphoma is incurable, with a median survival of 5-7 years. Therefore, there is a need to find more effective treatments with fewer side effects. 

Both lenalidomide-based and acalabrutinib inhibitor-based regimens have demonstrated significant clinical activities in MCL patients. The clinical and non-clinical observations suggest that acalabrutinib-lenalidomide-rituximab combined therapy may produce superior antitumor activity compared to one drug alone. 

This is a single arm study. Patients will take medication orally and intravenous (IV). Cycles will be 1-12, 1 cycle = 28 days. 

All patients will be followed for survival until end of study or until sponsor ends the study. Patients will continue on treatment as long as they are responding to therapy and not experiencing unacceptable side effects.