HSF1 and B-cell chronic lymphocytic leukemia: Since HSP70 overexpression is co-responsible for the reduced response to chemotherapy [6], allowing cancer cell survival in a “stressful” environment, and strengthened by our previous study on the correlation between therapeutic response after chemo-immunotherapy and HSP70 and HSF1 levels, we evaluated the expression of these two proteins in CLL patients who failed treatment with ibrutinib, experiencing disease progression during its assumption.