Lack of apoptosis of Sézary cells in the circulation following oral bexarotene therapy

Summary Background Apoptosis of malignant cells has been suggested as an important mechanism of the action of bexarotene in the treatment of cutaneous T‐cell lymphoma (CTCL). Objectives Our purpose was to examine the in vivo and in vitro responses of patients with Sézary syndrome treated with oral bexarotene and assess them for apoptosis of the Sézary cells. Methods Six patients with CTCL with circulating Sézary cells, participating in a clinical trial of oral bexarotene (300 mg m−2 daily) were included in the study. Peripheral blood from the patients was analysed for in vivo and in vitro apoptosis. Results None of the six patients demonstrated in vivo apoptosis. In vitro apoptosis of Sézary cells was demonstrated in one patient following exogenous bexarotene. Conclusions Apoptosis is not detectable in the circulation of patients with Sézary syndrome treated with bexarotene.