Background: Leukocyte-Associated Immunoglobulin-like Receptor (LAIR)-1 and LAIR-2 are members of the Leukocyte Receptor Complex (LRC) (An & Brodsky, 2016). LAIR-1 is a co-inhibitory receptor expressed on several subsets of immune cells, and functions to delimit immune responses (Meyaard et al., 1997). LAIR-2 is a secreted protein with homology to the transmembrane protein LAIR-1 (Lebbink et al., 2008). In cancer, it is hypothesized that LAIR-1 expression on several subsets of leukocytes prevents optimal immune responses by limiting both innate and adaptive immune functionality. LAIR-1 serves to suppress anti-tumor immunity through the inhibition of stimulatory signaling pathways. Specifically, LAIR-1 is a checkpoint and adhesion receptor on T cells that limits T cell activation and increases adhesion to collagens (Meyaard, 2008). LAIR-2 is capable of blocking LAIR-1 functional interactions with ligands, resulting in improved immune function on multiple immune cell subsets. Dysregulation of LAIR-1 ligands in the tumor microenvironment results in excessive production of collagens and complement C1q as well as altered forms of collagens, that leads to immune inhibition through binding to LAIR-1+ immune cells. NC410 is a dimeric form of the LAIR-2 protein fused to a human Fc domain of the immunoglobulin (Ig) subtype IgG1. The rationale for developing NC410 as a cancer therapeutic is based on nonclinical data demonstrating LAIR-1 signaling blockade can improve the immune response. Because LAIR-2 binds to ligands shared with LAIR-1 with increased affinity, NC410 acts as a decoy receptor for LAIR-1 ligands releasing suppression from myeloid cells and T cells and promoting anti-tumor immunity. NC410 may also mediate remodeling of the tumor extracellular matrix, further contributing to anti-tumor activity. Methods: This is a multi-center, first in human, phase 1/2, open-label, single-armed study to determine the safety and tolerability, define maximum tolerated dose (MTD) and/or pharmacologically active dose, assess preliminary efficacy, and explore predictive and pharmacodynamic biomarkers of NC410 in subjects with advanced or metastatic solid tumors. Key eligibility criteria include measurable disease based on RECIST v1.1 and being able to consent for collection of biopsies at screening and on treatment. Phase 1 is a classic 3+3 dose escalation design to determine the safety, tolerability, DLT, MTD and recommended phase 2 dose (RP2D) (NCT04408599). Ongoing exploratory analyses include the assessment of predictive biomarkers associated with treatment benefit, and pharmacodynamic markers associated with study drug activity. Phase 2 is going to enroll ovarian, colorectal, NSCLC, H&N, and gastric carcinomas and other tumors depending on biomarker data available from the Phase 1 part of the study. Clinical trial information: 04408599.