Phase II Study of Rituximab in Newly Diagnosed Stage IA Nodular Lymphocyte-Predominant Hodgkin Lymphoma (NLPHL): A Report From the German Hodgkin Study Group (GHSG)

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare subtype of Hodgkin lymphoma (HL) accounting for about 5% of cases. The clinical course is usually more indolent than in classical HL (cHL) resulting in an excellent long-term prognosis. This is particularly true for patients diagnosed with early-stage NLPHL representing the majority of cases. However, current standard treatment consisting of chemotherapy and/or radiotherapy (RT) is associated with an increased risk of late toxicity. Thus, there is a need for novel treatment strategies. Since CD20 is consistently expressed on the malignant lymphocyte-predominant (LP) cells, anti-CD20 antibody treatment appears to be a promising option. After impressive response rates were reported in relapsed NLPHL patients, the German Hodgkin Study Group (GHSG) initiated a trial to evaluate the anti-CD20 antibody rituximab in newly diagnosed stage IA NLPHL without clinical risk factors.

Between June 2006 and October 2007, 29 patients from 23 sites were enrolled in this multicenter phase II trial. Study entry was restricted to adult patients (age 18 to 75) with biopsy-proven stage IA NLPHL without clinical risk factors. Treatment consisted of four weekly infusions of the anti-CD20 antibody rituximab at a dose of 375 mg/m². Efficacy endpoints included remission status as assessed by computed tomography (CT) four weeks after completion of treatment, overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) at two years; feasibility endpoints were acute treatment-related toxicities, adverse events, dose reductions and therapy delays.

Twenty-eight patients were eligible for the final analysis of this phase II trial; 71.4% of patients were male, 72% had supradiaphragmatic disease and the median age was 40 years. Treatment was conducted in the outpatient setting in the majority of cases. Rituximab was well tolerated; no grade III/IV toxicities were observed. Transfusions of erythrocytes or platelets were not required. At final restaging four weeks after the last rituximab application, 24 patients (85.7%) were in CR/CRu and four patients (14.3%) had partial remission (PR). Thus, overall response rate (ORR) was 100%. After a median follow-up of 43 months, all patients were still alive. Progression-free survival rate estimates at two, three and four years were 85.3%, 81.4% and 77.1%, respectively. Seven patients (25%) have relapsed and two patients developed secondary solid tumors. All patients with NLPHL relapse were successfully salvaged.

The results of the present trial confirm the previously reported excellent response of NLPHL patients to rituximab. However, with a relapse rate of 25% at a median observation time of 43 months, rituximab does not seem to be as effective as RT alone or combined-modality strategies in stage IA NLPHL patients. Nonetheless, anti-CD20 antibodies have a favorable toxicity profile and may be offered to selected patients who are at particular risk for long-term side effects such as secondary malignancies. In addition, the combination of anti-CD20 antibodies and chemotherapy may also improve efficacy and decrease toxicity of NLPHL treatment in early unfavorable, advanced or relapsed disease.

No relevant conflicts of interest to declare.