Hypogammaglobulinemia in pts receiving rituximab immunotherapy and the impact of rituximab maintenance.

Abstract

8088 Background: Several randomized studies demonstrated that rituximab maintenance (RM) prolongs PFS but not OS following induction with rituximab immunotherapy (I) alone or chemoimmunotherapy (CI) in patients (pts) with indolent lymphoma. The long-term impact of rituximab (R) on immune reconstitution has not been well studied; however R has been associated with hypogammaglobulinemia (hypogam) with recurrent infections. This retrospective study sought to evaluate the relationship between R, hypogam, and treatment with intravenous immune globulin (IVIG). Methods: We identified 215 pts treated with R for lymphoma between 12/1998 and 4/2009 and also had quantitative serum immunoglobulin levels (sIg) evaluated prior to and after treatment with R. Data on the use of IVIG was collected. Frequencies were compared using Pearson χ2. Results: Histologies included: DLBCL, N=68; FL, N=42; CLL/SLL, N=38; MZL, N=26; MCL, N=22; other subtypes, N=19. Pts received a median of 6 doses of R (range:2–50). Prior to treatment with R, 85% (183/215) of pts had normal sIg levels and 15% (32/215) had low levels. Histologies among 32 pts with baseline hypogam were well distributed: DLBCL, N=10; CLL/SLL, N=5; FL, N=5; MZL, N=4; MCL, N=2; other, N=6. Of 183 pts with normal sIg levels prior to R, 26.7% (49) received RM while 73.2% (134) received R as I or CI alone. Hypogam was documented in 39% (71/183) of pts with baseline normal sIg levels following R. RM was associated with a higher risk of developing hypogam, 55% (27/49) compared to 33% (44/134) receiving I or CI alone, p=0.006. IVIG was administered to 13% (23/183) of pts with normal baseline sIg. Among patients who received RM, 20% (10/49) received IVIG compared to 10% (13/134) among patients treated with I or CI alone, p=0.05. IVIG for treatment of symptomatic hypogam was administered to 10% (18/183) of pts with normal sIg prior to R therapy. Conclusions: R was associated with developing hypogam in 39% of pts with normal baseline sIg. Pts receiving RM had a significantly higher risk of developing hypogam and requiring IVIG. The risk of symptomatic hypogam should be considered in the use of R maintenance. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Genentech, GlaxoSmithKline, sanofi-aventis Physicians' Education Resource Amgen, Biogen Idec, Genentech, GlaxoSmithKline, Roche