Depletion of T lymphocytes is correlated with response to temozolomide in melanoma patients

Therapeutic strategies to deplete lymphocytes, especially regulatory T cells, in cancer patients have been proposed to increase the benefits of (immuno)chemotherapy. In this study, we explored the influence of temozolomide (TMZ) on different T-cell populations and addressed if the depletion of CD4(+) T cells would be associated to the clinical benefits of TMZ. Patients were treated with TMZ (150 mg/m(2) daily, every two weeks on a four-week schedule) until disease progression. Changes in T-lymphocyte subsets were characterized by flow cytometry. All patients enrolled in this study had histologically verified unresectable stage IV melanoma. Objective responses were induced in 12.5% of the patients, while 42.5% of them obtained short-term disease stabilization. The median progression-free survival (PFS) of this patient cohort was 8.7 mo. Lymphopenia (