Comprehensive Surfaceome Profiling to Identify and Validate Novel Cell-Surface Targets in Osteosarcoma

Yifei Wang, Xiangjun Tian, Wendong Zhang, Zhongting Zhang, Rossana Lazcano, Pooja Hingorani, Michael E. Roth, Jonathan D. Gill, Douglas J. Harrison, Zhaohui Xu, Sylvester Jusu, Sankaranarayanan Kannan, Jing Wang, Alexander J. Lazar, Eric J. Earley, Stephen W. Erickson, Tara Gelb, Philip Huxley, Johanna Lahdenranta, Gemma Mudd, Raushan T. Kurmasheva, Peter J. Houghton, Malcolm A. Smith, Edward A. Kolb, Richard Gorlick

Immunoconjugates targeting cell-surface antigens have demonstrated clinical activity to enable regulatory approval in several solid and hematologic malignancies. We hypothesize that a rigorous and comprehensive surfaceome profiling approach to identify osteosarcoma-specific cell-surface antigens can similarly enable development of effective therapeutics in this disease. Herein, we describe an integrated proteomic and transcriptomic surfaceome profiling approach to identify cell-surface proteins that are highly expressed in osteosarcoma but minimally expressed on normal tissues. Using this approach, we identified targets that are highly expressed in osteosarcoma. Three targets, MT1-MMP, CD276, and MRC2, were validated as overexpressed in osteosarcoma. Further, we tested BT1769, an MT1-MMP-targeted Bicycle toxin conjugate, in osteosarcoma PDX models. The results showed BT1769 had encouraging anti-tumor activity, high affinity for its target and a favorable pharmacokinetic profile. This confirms the hypothesis that our approach identifies novel targets with significant therapeutic potential in osteosarcoma.