Assessing the efficacy of a ROR1:PD-L1:CD2 multispecific T cell engager in ROR1-positive and -negative neuroblastoma models

PROJECT SUMMARY/ABSTRACT Few children with recurrent neuroblastoma survive. New therapies, particularly immunotherapies, are badly needed. Some promising results have recently been presented from neuroblastoma trials with a CAR T therapy demonstrating that redirected T cell therapeutics have a promising role to play in the future. We

propose to redirect T cells to kill neuroblastoma cells using a multispecific T cell engager (MTE) that binds ROR1, PD-L1, and CD3. ROR1 is targeted because it is expressed in most neuroblastoma patients’ tumors and has been shown to be necessary for tumor initiation, migration, and other aggressive cancer features in

multiple types of cancer. PD-L1 is targeted because cells surrounding ROR1-positive cells that are being killed by the MTE will upregulate PD-L1 in response to the interferon gamma that is released by the engaged T cells. While PD-L1 upregulation is normally a defense mechanism against immune surveillance, our molecule

converts it into a cancer vulnerability because the more cancer cells upregulate PD-L1, the better T cells will be able to engage and kill them due to the PD-L1 and CD3 binding motifs on the MTE. Concerns about on-target, off-cancer toxicity due to PD-L1 expression on normal human tissues are mitigated by a recent human clinical

trial results showing that Davoceticept, an MTE that targets PD-L1, achieved good cancer control at doses that were well tolerated in the clinical trial. We propose the following: Aim 1: Determine the extent to which patient- derived neuroblastomas are vulnerable to R2P3 plus activated T cells. Aim 2: Determine R2P3 efficacy in

pediatric tumors that are heterogeneous for ROR1 expression. The innovation stems from co-targeting ROR1 and PD-L1, which addresses two common mechanisms of resistance to redirected T cell therapies, namely target heterogeneity and upregulation of PD-L1. Further innovation relates to the MTE itself, which contains

single domain binders of ROR1, PD-L1, and CD3, which intends to overcome the manufacturing challenges associated with heavy-light chain pairing. The significance of our proposal is that the molecule we have designed could rapidly advance to human clinical trials for children with neuroblastoma and other pediatric

solid tumors (e.g., Ewing sarcoma, rhabdomyosarcoma, osteosarcoma) if the results from these studies support further clinical development. Over a half century of failed clinical trials in recurrent neuroblastoma patients has taught us that bold, creative, and thoughtful new approaches must be advanced.