RETINOIC ACID-INDUCED APOPTOSIS AND REGRESSION OF A REFRACTORY EPSTEIN-BARR VIRUS-CONTAINING T-CELL LYMPHOMA EXPRESSING MULTIDRUG-RESISTANCE PHENOTYPES

The virus-associated T cell leukaemias/lymphomas are characterized by a poor prognosis primarily because of the rapid emergence of drug resi stance which may lead to failure of subsequent chemotherapy. We report here a case of Epstein-Barr virus-associated T cell lymphoma which re lapsed soon after chemotherapy and radiotherapy. The neoplastic cells of the relapsed tumour expressed high levels of multi-drug resistance gene (mdr1)-related P-glycoprotein and glutathione-S-transferase-pi, b oth of which were absent in the pre-chemotherapy tumour tissues. Empir ical treatment with oral 13-cis-retinoic acid (RA) was then given with subsequent complete disappearance of the tumour. The therapeutic effe ct of RA appears to act through an apoptotic process. in accordance wi th our previous report of a successful salvage of a refractory Ki-1 la rge cell lymphoma, RA appears to be a potentially useful drug for some specific type T-cell lymphomas.