Abstract 4406: ROR1 targeted delivery of OSU-2S, a non-immunosuppressive FTY720 derivative, exerts potent cytotoxicity in mantle cell lymphoma in-vitro and in-vivo
Authors: Mani Rajeswaran , Chiang Chi-Ling , Frissora Frank W. , Yan Ribai , Mo Xiaokui , Baskar Sivasubramanian , Rader Christoph , Phelps Mitch , Chen Ching-Shih , Lee Robert , Byrd John , Baiocchi Robert , Lee L James , Muthusamy Natarajan 
Published: August 2015

Abstract
Treatment of mantle cell lymphoma (MCL), an uncommon non-Hodgkin's lymphoma, remains challenging despite numerous therapeutic advances. We have previously shown the preclinical effect of FTY720 (Fingolimod) against MCL through down modulation of cyclin D1, the protein almost uniformly over-expressed in this disease. Herein, we describe the potent direct cytotoxicity of OSU-2S, a novel non-immunosuppressive FTY720 derivative in MCL cells and evaluate tumor directed lipid based nanoparticle formulation of OSU-2S designed to selectively deliver to ROR1+ MCL cells.
OSU-2S is a FTY720 derivative that does not traffic T cells and exhibits potent cytotoxicity in MCL cell lines and in MCL patient-derived primary cells (p = 0.0049). Exploratory studies aimed to identify the best combination therapies identified induction of cell surface CD74 in primary MCL cells treated with OSU-2S. Similarly, induction of cell surface CD74 was also confirmed in JeKo and Mino cells. Evaluation of OSU-2S and anti-CD74 antibody, milatuzumab in cell lines and primary MCL cells revealed enhanced cytotoxicity compared to either of the agents alone.
B-cell malignancy restricted expression of receptor tyrosine kinase ROR1 in MCL, chronic lymphocytic leukemia (CLL) and subset of pediatric acute lymphocytic leukemia (ALL) has been reported. Consistent with this, JeKo, Mino and primary MCL cells but not normal B cells expressed ROR1. As tumor directed delivery of cytotoxic cargo offers the potential to further enhance the therapeutic index of cancer therapeutics such as OSU-2S, we developed a lipid-based OSU-2S nanoparticle (OSU-2S-LP) tethered with an anti-ROR1 mouse monoclonal antibody (2A2) to form 2A2-OSU-2S-ILP that mediated selective cytotoxicity of MCL.
Testing of immunonanoparticle formulation on JeKo, Mino cell lines and primary lymphoma cells showed selective cytotoxicity of 2A2-OSU-2S-ILP in MCL (p&lt;0.001) compared to other controls, including non-targeted formulation (OSU-2S-LP), non-specific antibody (IgG-OSU-2S-ILP) or empty targeted formulation (2A2-Empty-ILP). In-vivo treatment with 2A2-OSU-2S-ILP in Mino cell line xenografted NOD-SCID-Gamma−/− mice revealed significantly diminished tumor growth compared to the control (p = 0.0001). These findings describe the novel OSU-2S molecule as a successor of FTY720 that is active against MCL. OSU-2S enhanced CD74 expression can be exploited in combination therapy with milatuzumab which is in human clinical trials. Importantly, the tumor antigen ROR1 directed delivery system for increasing the payload selectively to the cancer cells thus obviating the exposure of chemotherapeutics and targeted therapeutics to other unintended target cells has broad implications in diverse ROR1+ malignancies.
Citation Format: Rajeswaran Mani, Chi-Ling Chiang, Frank W. Frissora, Ribai Yan, Xiaokui Mo, Sivasubramanian Baskar, Christoph Rader, Mitch Phelps, Ching-Shih Chen, Robert Lee, John Byrd, Robert Baiocchi, L James Lee, Natarajan Muthusamy. ROR1 targeted delivery of OSU-2S, a non-immunosuppressive FTY720 derivative, exerts potent cytotoxicity in mantle cell lymphoma in-vitro and in-vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4406. doi:10.1158/1538-7445.AM2015-4406