Acalabrutinib for the Treatment of Relapsed or Refractory Autoimmune Hemolytic Anemia in Patients With Chronic Lymphocytic Leukemia

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Assent, when appropriate, will be obtained per institutional guidelines * Agreement to allow the use of archival tissue from diagnostic tumor biopsies * If unavailable, exceptions may be granted with study principal investigator (PI) approval * Eastern Cooperative Oncology Group (ECOG) =\< 2 * "Warm" or "cold" AIHA in patients with CLL, relapsed/refractory (RR) after first line treatment with oral prednisone (with or without rituximab), defined as: * Anemia (hemoglobin \[Hgb\] =\< 10 g/dL; or Hgb \> 10 g/dL dependent on transfusions or maintenance therapy (rituximab, cyclosporin, etc) to maintain this level of hemoglobin, and * Laboratory evidence of hemolysis - presence of 3 of 4 markers (increased reticulocyte count, increased indirect bilirubin, increased lactate dehydrogenase, absent haptoglobin) * Positive direct antiglobulin test (DAT) (score \>= 1+) - either immunoglobulin G (IgG) DAT, C3 DAT, or both. Eligibility of patients with Coombs-negative AIHA should be confirmed by the trial investigator at each respective study site * Histologically or flow cytometry confirmed diagnosis of CLL/small lymphocytic lymphoma (SLL) * Participant must be able to swallow tablets or capsules * Absolute neutrophil count (ANC) \>= 500/mm\^3 unless due to disease involvement in the bone marrow or autoimmune neutropenia (within 30 days prior to day 1 of protocol ther…