Combination Immunotherapy with a CpG Oligonucleotide and Rituximab (R) Augments the Immunological Response and Favorably Alters the Malignant Microenvironment of Follicular Lymphoma (FL).

The malignant microenvironment of FL, including T cells, macrophages and follicular dendritic cells, contributes to disease pathogenesis and represents a rational therapeutic target. Gene expression profiling and immunohistochemistry studies have confirmed that degree and type of immune response in the malignant FL lymph node impacts clinical outcome. CpG oligonucleotides have pleotropic effects on both the innate and adaptive immune systems, including increased antigen expression, enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and shifting the immune response in a TH-1 direction. These agents therefore have significant potential to manipulate the immune response to FL, and alter the malignant microenvironment in a favorable way. We combined a CpG oligonucleotide (1018 ISS, 0.2 mg/kg sc weekly x 4 beginning day 8) with standard R in patients (pts) with relapsed/refractory, histologically confirmed FL, and comprehensively evaluated immunological changes following the combination. 22 pts (10 female; median age 55) with FL sensitive or naive to R were enrolled. FcγRIIIA polymorphism status was FF n=9, VF n=12, VV n=1. Treatment was well-tolerated with no significant adverse events attributable to therapy. Baseline and post therapy evaluations were performed on blood and the CpG injection sites in all pts. Compared to baseline, 7 pts demonstrated significant increases in ADCC after therapy using a conventional chromium-release assay. Circulating CD3-positive cells increased in 11 pts. Increased IFN-γrelease by Elispot occurred in 5 pts. 10 pts had significant increases in neutrophils, T cells, and macrophages in skin biopsies of CpG injection sites performed 24 hours post therapy compared with baseline. Pre- and post-biopsies of tumor tissue (including lymph nodes and bone marrow) were performed in 5 pts, and in all cases a significant infiltration of T cells (CD8 > CD4) and macrophages were observed following treatment. Clinical responses per Cheson criteria were observed in 45% of pts; median PFS was 18 months in responding pts, and 9 months for entire group; 12 pts have not yet required further therapy for FL. In conclusion, this group of pts with relapsed FL had favorable clinical outcome despite adverse prognostic factors. The addition of CpG to R had measurable and reproducible local and systemic immune effects in a substantial subset of pts. Unlike other cytokine/antibody combinations, this study is the first to histologically confirm perturbation of the local immune malignant microenvironment following systemic biological therapy of FL.