Printer-Friendly pageASCO 2006 Abstract
Preliminary immune response (IR) results of a Phase 2 study with idiotype (Id) immunotherapy after treatment with CVP and rituximab for follicular non-Hodgkin's lymphoma (FL)
Author Block: J. P. Leonard, K. Mason, T. Theriault, K. Milner, T. Sornasse, D. Ingolia, M. Mayo, D. W. Denney, Genitope Corporation 2002-09 Study Group; Weill Medical College of Cornell University, New York, NY; Genitope Corporation, Redwood City, CA; Genitope Corporation, Redwood City, CA; Genitope Corporation, Redwood City, CA
Background: Idiotype (Id) is a collection of unique immunogenic epitopes present on the surface of malignant B cells. Keyhole limpet hemocyanin (KLH) is a carrier protein used to increase antigen immunogenicity. MyVax® Personalized Immunotherapy consists of the patient- and tumor-specific Id protein produced using molecular techniques conjugated to KLH and administered in a series of SQ immunizations with the adjuvant GM-CSF. Idiotype vaccines were first studied in combination with various chemotherapeutic agents as part of initial treatment for FL. Given the wide-spread usage of rituximab in treating FL, the nature of IRs in patients immunized with MyVax® Personalized Immunotherapy following rituximab treatment are of interest. CD19+ B cell counts following treatment with rituximab were analyzed for correlation with patient-specific Id-KLH induced humoral IR data.
Methods: In a Phase 2 study, MyVax® Personalized Immunotherapy following rituximab is being evaluated for patients who failed to achieve at least a PR after 8 cycles of CVP and maintain the response over a 6 month rest period. Eligible patients received 4 weekly doses of rituximab followed by a 13- or 26-week rest period. Patients who achieved and maintained a PR or better then received 8 immunizations with MyVax® Personalized Immunotherapy over 14 weeks. CD19+ B cells and humoral IRs against Id and KLH were monitored during and post-immunization.
Results: 87 pts received rituximab. 52 pts went on to immunization. Median CD19 counts for all arms of the study were lower post rituximab treatment (pre-treatment median = 76 cells/ul (N = 57) vs. post treatment = 13 cells/ul (N = 51 evaluable); p < 0.0001). IRs were assessed during immunization and 2, 8, 20, 32, 44 & 56 weeks post immunization. 49/52 (94%) evaluable pts were able to mount anti-KLH humoral IRs post rituximab. The magnitude of the anti-KLH response was significantly higher in pts with higher B cell counts when beginning immunizations. Anti-Id IRs were also observed.
Conclusions: Humoral IRs to KLH occur in pts receiving MyVax® Personalized Immunotherapy and correlate with regeneration of B cells post rituximab but appear less robust than in rituximab-naïve pts.