IMMU-50. BBB CROSSING NANO-IMMUNOMEDICINE COMBINATION THERAPY TO TREAT BRAIN PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA

Abstract

Abstract INTRODUCTION Lack of standard treatment of Primary Central Nervous System Lymphoma (PCNSL) was acknowledged in phase III intergroup study (HOVON 105/ALLG NHL 24). PCNSL incidence is increasing for unknown reasons, particularly among persons over 65 years. One of the major limitations of successful treatment of PCNSL is the blood-brain barrier (BBB), which prevents drug delivery into the brain. METHODS Polymer nanoconjugate based on biodegradable poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA) was used for treatment of BALB/C mice with intracranially inoculated murine A20 lymphoma. PHPMA-based nanoconjugates have defined synthesis strategy for BBB transcytosis, tumor targeting, and cancer cell killing. Nano immunodrug PHPMA/AP-2/Fab’/c-Myc inhibitor/H6 conjugate contains multiple AP-2 peptides for efficient delivery across the BBB and Fab’ fragments of αCD20 mouse Ab for CD20 receptor crosslinking on PCNSL cells. c-Myc inhibitor bound via a disulfide bond is transferred to the cytoplasm followed by cleavage. The therapeutic efficacy and survival were evaluated together with spectral flow cytometry and RNA-seq bioinformatic analysis of tumor tissues. RESULTS Nanoconjugates were able to penetrate BBB and accumulate in brain parenchyma. The best survival results were obtained for the group where nanoconjugate with αCD20 Fab’ causing tumor cell apoptosis and c-Myc antisense inhibitor was combined with αPD-1 checkpoint inhibitor. Survival compared to PBS-treated controls was significant (P=0.0006 by ANOVA). Ex vivo analysis of A20 brain lymphoma tissue after treatment with nanoconjugates demonstrated reduction of Tregs, associated with downregulation of IL-10 and IL-1β in plasma. Spectral flow cytometry revealed activation of tumor infiltrating T lymphocytes and M1 macrophages in lead nanodrug treated groups. RNA-seq data correlated with flow cytometry results indicating the activation of genes linked to IFN-γ pathway important for anti-tumor response and M1 macrophage activation. Immunostaining confirmed a marked increase of M1-specific iNOS expression in the nanodrug-treated tumors. Support: NIH grants: R01 CA188743, R01 CA206220, R01 CA209921