Mature results of a phase II study of rituximab therapy for nodular lymphocyte-predominant Hodgkin lymphoma

Purpose: Universal expression of CD20 by malignant cells in nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) led us to evaluate rituximab (R) as a therapeutic option. Patient and Methods: Patients with previously treated or newly diagnosed NLPHL were treated with R (375 mg/m² once per week for 4 weeks) or, after a protocol amendment, with R plus R maintenance (MR; administered once every 6 months for 2 years). Primary and secondary outcome measures were progression-free survival (PFS) and overall response rate (ORR), respectively. Results: A total of 39 patients were enrolled (R, n = 23; R + MR, n = 16). After four once-per-week treatments, ORR was 100% (complete response, 67%; partial response, 33%). At median follow-ups of 9.8 years for R and 5 years for R + MR, median PFS were 3 and 5.6 years (P = .26), respectively; median overall survival (OS) was not reached. Estimated 5-year PFS and OS for patients treated with R versus R + MR were 39.1% (95% CI, 23.5 to 65.1) and 95.7% (95% CI, 87.7 to 100) versus 58.9% (95% CI, 38.0 to 91.2) and 85.7% (95% CI, 69.2 to 100), respectively. Nine of 23 patients experiencing relapse had evidence of transformation to aggressive B-cell lymphoma; six of these patients had infradiaphragmatic involvement at study entry. Conclusion: R is an active agent in NLPHL. Although responses are not durable in most patients, a significant minority experience remissions lasting > 5 years. R + MR results in a nonsignificant increase in PFS compared with R. R may be considered in the relapsed setting for NLPHL. The potential for transformation of NLPHL to aggressive B-cell lymphoma underscores the importance of rebiopsy and long-term follow-up.