Panobinostat in combination with rituximab in heavily pretreated diffuse large B-cell lymphoma: Results of a phase II study

This is a phase II study of panobinostat, an oral pan-HDAC inhibitor, combined with rituximab in patients with relapsed diffuse large B cell lymphoma. Panobinostat was administered orally 3 times a week every other week on a 28-day cycle. Rituximab was administered weekly during the first cycle, then on Day 1 of cycles 2 to 6. Patients without disease progression after 6 cycles continued panobinostat monotherapy for up to 6 additional cycles in the absence of disease progression. Eighteen eligible subjects were enrolled, and 18 were evaluable for response. The overall response rate was 11% (90% CI [2%-34%]) with 2 subjects having a partial response. The duration of response in these subjects was 51 and 60days. Five additional subjects had stable disease with 3 subjects having tumor reduction between 27 and 44%, not meeting criteria for partial response. One subject with stable disease remained on therapy a total of 12 cycles. The most common toxicities while on study were thrombocytopenia (14 patients, 78%); fatigue (11, 61%); anemia (10, 56%); diarrhea (8, 44%); and nausea, lymphopenia, anorexia, and hypophosphatemia (5 each, 28% of patients), the majority of which was grade 2 or less. These data indicate that the combination of panobinostat with rituximab is able to induce responses in a limited number of subjects with relapsed diffuse large B cell lymphoma.