The goal of this observational study is to compare the efficacy of advanced immunochemotherapy and classical immunochemotherapy in relapsed/refractory high grade B cell lymophoma patients. The main question it aims to answer is: Does advanced immunochemotherapy, including CAR-T therapy, bispecific antibody, and antibody-drug conjugate offer superior survival outcomes than when treated with classical immunochemotherapy, such as proteasome inhibitors, immune modulatory drugs, and monoclonal antibodies? Researchers will compare patients receiving advanced immunochemotherapy with those receiving classical immunochemotherapy to determine if advanced therapies result in better survival outcomes. Laboratory findings and electronic medical records (EMR) from participants will be used to assess survival outcomes and treatment-related safety profiles.