RecruitingPhase 2ProcedureTafasitamab, Lenalidomide and Venetoclax for the Treatment of Relapsed or Refractory Mantle Cell LymphomaThis phase II trial tests how well tafasitamab, lenalidomide and venetoclax work in treating patients with mantle cell lymphoma that has come back (after a period of improvement) (relapsed) or that has not responded to previous treatment (refractory). Tafasitamab is a monoclonal antibody that may interfere with the ability of cancer cells to grow and spread. Lenalidomide is in a class of medications called immunomodulatory agents. It works by helping the immune system kill cancer cells. Venetoclax is in a class of medications called B-cell lymphoma-2 (Bcl-2) inhibitors. It may stop the growth of cancer cells by blocking Bcl-2, a protein needed for cancer cell survival. Giving tafasitamab, lenalidomide and venetoclax together may kill cancer cells more efficiently in patients with relapsed or refractory mantle cell lymphoma.