Key Inclusion Criteria:  Up to 5 prior regimens for MCL. Prior therapy must have included anthracycline- or bendamustine-containing chemotherapy and anti-CD20 monoclonal antibody therapy. Individuals must not have received prior therapy with a BTKi. At least 1 measurable lesion Platelet count ≥ 75,000/uL Creatinine clearance (as estimated by Cockcroft Gault) ≥ to 60 cc/min Cardiac ejection fraction ≥ 50%, no evidence of pericardial effusion as determined by an echocardiogram (ECHO), and no clinically significant electrocardiogram (ECG) findings Baseline oxygen saturation > 92% on room air  Key Exclusion Criteria:  Known history of infection with human immunodeficiency virus (HIV) or hepatitis B (HBsAG positive) or hepatitis C virus (anti-HCV positive). Individuals with a history of hepatitis infection must have cleared their infection as determined by standard serological and genetic testing History of a seizure disorder, cerebrovascular ischemia/hemorrhage, dementia, cerebellar disease, cerebral edema, posterior reversible encephalopathy syndrome, or any autoimmune disease with central nervous system (CNS) involvement Presence of fungal, bacterial, viral, or other infection that is uncontrolled or requiring IV antimicrobials for management  Note: Other protocol defined Inclusion/Exclusion criteria may apply.