Tratamiento del mieloma múltiple refractario o en recaída con mitoxantrona y altas dosis de dexametasona: estudio del mecanismo de resistencia a drogas inducido por glicoproteina-P 170 / Treatment refractory multiple myeloma or in relapse with mitoxantrone and high doses dexamethasone a study of the mechanism of drug resistence induced by P-glycoprotein 170

RESUMO

Treatment of refractory or relapsed multiple myeloma withmitoxantrone and high dose dexamethasone. Study of the mechanism of drug resistance induced by p-glycoprotein 170. One of the most studied mechanism of drug resistance is the induction of a gene (MDR) codifying for a protein (gp-170), which acts by decreasing the intracellular accumulation of various citotoxic drugs. The mechanisms of resistance for mitoxantrone are not yet well understood. As the prognosis of patients with multiple myeloma not responding initially to chemotherapy, or relapsing after achieving a response, is generally poor, the purpose of the present study is to evaluate the activity of mitoxantrone in refractory or relapsed multiple myeloma, as well as to study the ability of this agent to induce drug resistance through the mechanism of p-glycoprotein. Patients will be studied before and at the end of therapy for the expression of p-glycoprotein. Chemotherapy consists of mitoxantrone 12 mg/m²iv, day 1 plus dexamethasone 40 mg iv, daily for 4 days, in six monthly cycles.