Tafasitamab and Zanubrutinib for the Treatment of Patients With Newly Diagnosed Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma, TaZA CLL Study

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Assent, when appropriate, will be obtained per institutional guidelines * Age: \>= 18 years * Eastern Cooperative Oncology Group (ECOG) =\< 2 * Histologically or flow cytometry confirmed diagnosis of B-CLL/SLL as documented by medical records and with histology based on criteria established by the World Health Organization (WHO) * No prior treatment for CLL, except steroids and/or rituximab to treat autoimmune complications * Active disease meeting criteria for requiring treatment per the iwCLL 2018 guidelines * A minimum of any one of the following constitutional symptoms: * Unintentional weight loss \> 10% within the previous 6 months prior to screening * Extreme fatigue (unable to work or perform usual activities) * Fevers of greater than 100.5 degrees Fahrenheit (F) for \>= 2 weeks without evidence of infection * Night sweats without evidence of infection * Evidence of progressive marrow failure as manifested by the development of, or worsening of anemia or thrombocytopenia * Massive (i.e., \> 6 cm below the left costal margin), progressive or symptomatic splenomegaly * Massive nodes or clusters (i.e., \> 10 cm in longest diameter) or progressive lymphadenopathy * Progressive lymphocytosis with an increase of \> 50% over a 2-month period, or an anticipated doubling time of less than 6 months * Autoimmune anemia or thrombocytopen…