Avo In R/R And Previously Untreated MCL

This is an open-label, investigator-initiated, single-arm, multi-cohort phase 1/2 study to assess the safety and efficacy of the combination of acalabrutinib, venetoclax, and obinutuzumab (AVO) in relapsed/refractory (R/R) and untreated mantle cell lymphoma (MCL). The research study procedures include screening for eligibility and study treatment including evaluations and follow up visits. The names of the study drugs involved in this study are: * Acalabrutinib * Venetoclax * Obinutuzumab Participants will receive study treatment for as long as there are no serious side effects and the disease does not get worse. Participants will be followed for 5 years. It is expected that 72 people will take part in this research study. This is a Phase I/II clinical trial. Phase I clinical trials test the safety of investigational drugs and also tries to define the appropriate dose of investigational drugs to use for further studies. "Investigational" means that the drugs are being studied. * The U.S. Food and Drug Administration (FDA) has not approved venetoclax and obinutuzumab for this specific disease but it has been approved for other uses. * The U.S. Food and Drug Administration (FDA) has approved acalabrutinib as a treatment option for this disease.