Experience with 9-cis retinoic acid in patients with relapsed and refractory non-Hodgkin's lymphoma.

We conducted a phase II study to determine the efficacy and toxicity of 9-cis-retinoic acid (9-cis RA), a pan-retinoid receptor agonist, in the treatment of patients with relapsed and refractory NHL. Patients were eligible if they had histologically documented relapsed or refractory T cell or indolent B cell NHL. The first three patients enrolled received 70 mg/m2 of 9-cis RA orally twice a day, but the remaining patients received a single oral daily dose of 100 mg/m2. After 6 weeks of therapy, tumor response was assessed objectively. Response rate and toxicity were determined in all 29 eligible patients based on an intent-to-treat analysis. Four patients (14%) responded (3 PRs and 1 CR; 95% CI 4%-33%). One patient had a minor response, and eight had stable disease. Responses were observed in two (11%) of 19 patients with B-cell lymphoma and in two (20%) of 10 patients with T-cell lymphoma. The median time-to-treatment failure for the 29 eligible patients was 8 weeks. The most frequent toxic effects were dry skin, headache, hypertriglyceridemia, and hypercalcemia. Five patients discontinued therapy due to toxic side effects, but no toxic deaths occurred during the study. We conclude that 9-cis RA has a modest activity in relapsed and refractory NHL. In this study, responses were observed in patients with B-cell lymphomas and those with T-cell lymphomas.