ROR1 is a receptor tyrosine kinase-like orphan receptor with very low kinase activity in vivo 1. It functions primarily as a Wnt receptor, binding WNT5A ligand to activate downstream NF-κB signaling and inhibit canonical WNT3A-mediated pathways 12. In the inner ear, ROR1 is crucial for spiral ganglion neuron innervation of auditory hair cells 2, with mutations causing autosomal recessive deafness 2. ROR1 also forms complexes with ERBB2 via IGFBP5 ligand to enhance CREB oncogenic signaling 3. In cancer biology, ROR1 supports cancer stem cell maintenance through noncanonical WNT signaling, promoting epithelial-mesenchymal transition and chemoresistance 45. Cell surface ROR1 is expressed on ovarian, triple-negative breast, and lung adenocarcinomas, though expression on normal tissues including parathyroid, pancreatic islets, and gastrointestinal regions raises on-target off-tumor toxicity concerns for immunotherapies 6. ROR1 expression correlates with breast cancer metastasis and reduced survival 7. Clinically, ROR1 is an emerging immunotherapeutic target in mantle cell lymphoma and solid tumors, with ROR1-targeted biologics, antibody-drug conjugates, and degrader-antibody conjugates currently in development 8910.