The Effects of Arsenic Trioxide in Combination with Retinoic Acids on Cutaneous T-Cell Lymphoma Cell Lines.

Cutaneous T-cell lymphomas (CTCL) are characterized by an infiltration of the skin with malignant T cells. Curative treatments for aggressive entities such as Sézary syndrome have not been identified yet. Arsenic trioxide (AsO3) is used for the treatment of acute promyelocytic leukemia in combination with retinoids. As the latter are established treatment options in CTCL, we sought to evaluate the efficacy of AsO3 for mono- and combination therapy in vitro. Analyses for apoptosis, cell cycle inhibition, cytotoxicity and cell viability were made after incubation of CTCL cells with AsO3 alone or in combination with the retinoids all-trans-retinoic acid or bexarotene. While AsO3 induced apoptosis, retinoids did not at the time point of analysis. However, retinoids strongly reduced cell viability. Due to the efficient apoptosis induction, AsO3 might be a potentially suitable agent for CTCL treatment, although this effect was not increased by retinoids.