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 and
* Ibrutinib or acalabrutinib

At least 1 measurable lesion

Platelet count ≥ 75,000/uL

Creatinine clearance (as estimated by Cockcroft Gault) > or = to 60 mL/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). A history of hepatitis B or hepatitis C is permitted if the viral load is undetectable per 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.