1200 Leveraging the immunocompetent Vk*MYChCRBN model of multiple myeloma to determine and overcome T cell engager antibody resistance mechanisms by Natalie Bezman, Erin W Meermeier, Caleb Stein, Meaghen Sharik, Megan Du, Chang-Xin Shi, Yuan Xiao Zhu, Keith Abayasiriwardana, Timothy Fisher, Bas Baaten, Kristin Bompiani-Myers, P Leif Bergsagel, Marta Chesi