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. This evidence concerns the gene HSF1 and cancer.