Venetoclax in Combination With BEAM Conditioning Regimen for ASCT in Non-Hodgkin Lymphoma

The primary objective of this study is to establish the safety of V-BEAM conditioning regimen prior to autologous stem cell transplant in order to identify the recommended phase II dose (RPD2). This study will also seek to compare time to neutrophil engraftment and time to platelet engraftment of participants who receive V-BEAM and ASCT, compared to historical controls and among cohorts. And finally, it will determine the Progression Free Survival (PFS) and Overall Survival (OS) of V+BEAM followed by ASCT relative to historical controls of BEAM alone followed by ASCT. This will be a single-institution, open label, phase I study designed to evaluate the safety of this combination. The target population will be participants with NHL who are eligible for ASCT. Dose escalation will proceed using a standard 3 + 3 design with 5 dose levels, a minimum of 6 participants and a maximum of 30 participants will be required to identify the RP2D. If a participant does not take all scheduled doses of Venetoclax according to his/her cohort, the participant will be replaced because he/she has not taken enough drug to confirm safety at that dose level. Once the conditioning regimen has been delivered and autologous stem cells have been infused there is no further disease-directed treatment as part of this protocol. In accordance with routine practice the bone marrow transplant program at the Cleveland Clinic, participants receive supportive care and follow-up until disease relapse or death. In the absence of treatment delays during the conditioning regimen due to adverse events, participants will remain on study for 24 months or until one of the following criteria applies: * Disease progression * Intercurrent illness that prevents further administration of treatment * The investigator considers it, for safety reasons, to be in the best interest of the participant. * General or specific changes in the participant's condition rendering the participant unacceptable for further treatment in the judgment of the investigator. * Participants decision to withdraw from treatment (partial consent) or from the study (full consent) * Pregnancy during the course of the study for a child-bearing participant * Death, or * Sponsor reserves the right to temporarily suspend or prematurely discontinue this study. Participants will be followed for toxicity for 24 months after hospital discharge or until a protocol approved outcome. The first 3 months will be at the treating center and continued recommended follow-up should be at a minimum of 6 months, 12 months, 18 months and 24 months after hospital discharge or as clinically appropriate according to local practices. The clinical course of each event will be followed until resolution, stabilization, or until it has been determined that the study treatment or participation is not the cause. Serious adverse events that are still ongoing at the end of the study period will necessitate follow-up to determine the final outcome. Any serious adverse event that occurs after the study period and is considered to be possibly related to the study treatment or study participation will be recorded and reported immediately.