Frontline Therapy of Nodular Lymphocyte Predominant Hodgkin Lymphoma with Rituximab: The Stanford University Experience
Authors: Advani Ranjana H. , Horning Sandra J. , Hoppe Richard T. , Daadi Sarah , Allen John , Natkunam Yasodha , McMillan Alex , Bartlett Nancy L. 
Published: October 2019

Abstract
Abstract 2686

Background:
Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a rare subtype of HL (∼5%). This unique clinical entity is characterized by an indolent clinical course and unlike classical HL late relapses may occur. Standard treatment depends on stage and includes radiation therapy (RT) and/or chemotherapy which can be associated with an increased risk of treatment related late effects warranting investigation of other active agents. The malignant cells of NLPHL universally express CD20, therefore therapy with rituximab (R), the monoclonal anti-CD20 antibody, is a targeted option. We report our experience with R as front-line treatment for patients with NLPHL.

Methods:
Patients with newly diagnosed NLPHL and measurable disease were treated with R at 375 mg/m2 administered weekly × 4 or, after protocol amendment (February 2003) with R followed by 4 doses of R maintenance (RM) administered every 6 months for 2 years. Restaging studies were performed at 1, 3 and 6 months and then every 6 months until progression. All pathology was centrally reviewed.

Results:
Nineteen patients were enrolled between May 1999 and September 2006. The median age at treatment was 45 years (range 17–63), stage I (n=6), stage II (n=7), stage III (n=6). Ten patients were treated with R alone and 9 with R+RM. The median follow-up for R patients is 8.8 years (5–11.4) and for R+RM patients is 5 years (2.5–7.6). At the end of induction therapy with R alone, the overall response rate was 100% [complete response (CR) (n=10), CR unconfirmed (n=2) and partial response (n=7)]. The median progression free survival (PFS) for patients treated with R alone and R+RM is 50 months and 67 months, respectively (p=0.7; log rank test) and median overall survival (OS) not reached. The median follow up for patients without progressive disease at the time of this analysis was 6.9 years (range 2.5–11.5). The estimated PFS at 5 years is 51.7%, [95% CI 33.2–80.4] and at 10 years 35.4% [95% CI 17.7–70.8]. There was no difference in median PFS between patients with stages I-II versus III (5.6 years and 4.15 years respectively, p=0.58 [log rank test]). The estimated OS at 5 years is 93.3%, [95% CI 81.5–100] and 10 years 76% [95% CI 55.4–100]. Ten patients progressed (5 treated with R alone, 5 treated with R+RM) of whom 6 transformed to an aggressive B cell lymphoma (biopsy proven) at a median of 4.2 years [range 0.9–8]. Five of the 6 transformed patients had abdominal disease at initial diagnosis (stage III, n=4). Three patients died (2 aggressive NHL, 1 unknown).

Conclusion:
Rituximab is an active single agent in the treatment of newly diagnosed NLPHL with a median PFS of 5.6 years. R+ RM resulted in a non-significant increase in PFS compared to R alone. In this series, abdominal involvement was associated with transformation to an aggressive B cell lymphoma underscoring the need for biopsy at relapse. These results demonstrate a pattern of late relapse following rituximab, at least as great as the historical data with RT or RT + CT. Although R alone achieved proof of concept for a targeted therapy, its use should remain investigational as primary therapy of NLPHL.

Disclosures:
Advani: Genentech Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: Rituximab. Anti-CD20 agent that targets CD20 on NLPHL cells. Horning:Genentech: Employment, Equity Ownership.