In Situ Vaccination with Combination of Class B and Class C Toll-like Receptor 9 Agonist CpG Immune Adjuvant Nanoparticles to Induce a Systemic Anti-Lymphoma Response

Introduction: Treatment of relapsed and refractory aggressive B cell lymphomas is challenging, especially after autologous stem cell transplant or chimeric antigen receptor T cell therapy. CpG oligodeoxynucleotides (CpGs) mimic bacterial DNA and bind to toll-like receptor 9 (TLR9). TLR9 is expressed in the endosomes of innate immune cells and B lymphocytes as well as B cell lymphomas. CpG binding to TLR9 in these cells leads to a pro-inflammatory response and induces apoptosis of lymphoma cells by altering NF-kB activation. However, clinical utility of CpGs is limited due to difficulties delivering the DNA directly to the innate immune cells and lymphoma cells, and these DNA strands are easily degraded in biological fluids. Therefore, we designed a nano-carrier to deliver two classes of CpGs to improve clinical efficacy of CpGs in treating lymphoma. Class B CpGs (B-CpGs) mainly stimulate B cells while class C CpGs (C-CpGs) act on both B cells and plasmacytoid dendritic cells. Though C-CpGs are the focus of current clinical trials, B-CpGs may have a special a role in the treatment of lymphoma due to their more potent, direct cytotoxic effect on the malignant lymphoma cells. Here, we evaluated the anti-lymphoma effect of the combination of B-CpG nanoparticles (BNP) and C-CpG nanoparticles (CNP) by optimizing lymphoma cell death and immune stimulation.