Rituximab Active in Nodular Lymphocyte-Predominant Hodgkin Lymphoma

April 2014, Vol 5, No 3
Jayson Slotnik, JD, MPH
Managing Partner
Health Policy Strategies, Inc.
Bethesda, MD

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare type of Hodgkin lymphoma that represents approximately 5% of all cases. Unlike classic Hodgkin lymphoma, the malignant cells of NLPHL universally express CD20. Because rituximab (Rituxan) is an anti-CD20 monoclonal antibody, it has been evaluated as a treatment option for this patient population.

Previous preliminary results of a phase 2 clinical trial using single-agent rituximab in patients with NLPHL showed that the overall response rate was 100%, but the estimated median freedom from progression was less than 1 year. In a new study, researchers modified the study protocol of ri­tuximab induction with and without maintenance rituximab in NLPHL to evaluate patient response rate at 2 years (Advani RH, et al. J Clin Oncol. 2014;32:912-918).

The study included 39 patients with previously treated or with newly diagnosed NLPHL. The initial protocol

included 23 patients (ie, rituximab group) who received rituximab 375 mg/m2 administered once weekly for 4 weeks. The protocol was amended after this patient cohort had enrolled to include 16 patients (ie, rituximab plus maintenance group) who received maintenance dosing with rituximab 375 mg/m2 administered in 4 once-weekly doses at 6-month intervals for 2 years.

For patients with previously untreated disease, the median age at treatment was 38 years, and the median time from diagnosis to treatment induction was 4 months. The median time from original diagnosis of NLPHL to study entry in patients experiencing relapse was 12.7 years, and the median age at treatment was 44 years. The primary end point was progression-free survival (PFS), and the secondary end points were complete response and overall response rate.

After 4 weekly treatments, the overall response rate was 100%, with 67% of patients achieving complete response and 33% achieving partial response. No difference in the overall response rate was observed in previously treated patients versus the treatment-naïve patients.

At a median follow-up of 9.8 years in the rituximab group, the PFS was 3 years. At the median follow-up of 5 years in the rituximab plus maintenance group, the PFS was 5.6 years. The median overall survival (OS) was not reached in either group. The estimated 5-year PFS and OS rates for patients in the rituximab group compared with patients in the rituximab plus maintenance group were 39.1% and 95.7% versus 58.9% and 85.7%, respectively.

Treatment-related adverse events were minimal in both groups, and no grade 3 or 4 toxicities were observed. A total of 23 patients experienced relapse, and 9 of these patients had evidence of transformation to aggressive B-cell lymphoma.

The researchers concluded that rituximab is well-tolerated and is an active single agent in patients with NLPHL who had received no previous treatment and in patients with relapsed disease. Although the responses are not durable in the majority of the patients, a substantial minority experience remission lasting more than 5 years.

Because single-agent rituximab is not curative for NLPHL, it should be primarily considered in patients in the relapsed setting. The potential for transformation of NLPHL to aggressive B-cell lymphoma underscores the importance of repeated biopsy and longer-term follow-up.

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