Publications

The development of effective antibody therapeutics has been hampered by a lack of methods to measure drug delivery and activity within tumors at single-cell resolution. Here we introduce single-cell spatial pharmacobiology (SSP), an experimental and analytical framework that integrates in situ imaging of a systemically infused, fluorescently labeled therapeutic antibody with high-plex spatial proteomics to quantify antibody distribution, target engagement and tumor microenvironment (TME) architecture. We applied SSP to tumor tissues from participants with head and neck squamous cell carcinoma and pancreatic ductal adenocarcinoma who received the antibody panitumumab-IRDye800 in phase 1 trials. SSP identified pronounced spatial heterogeneity in single-cell drug delivery and target engagement, shaped by conserved stromal barriers, including periostin-rich extracellular matrix assemblies and fibroblast-activation-protein-positive cancer-associated fibroblast neighborhoods, which were associated with reduced antibody delivery in both tumor types. SSP measures drug-target-TME interactions in human tumors and can support studies of resistance mechanisms, dosing strategies and discovery of spatial biomarkers for precision oncology.

JTD Keywords: Cancer, Diffusion, Fibroblasts, Gemcitabine, Head, Inhibitor, Monoclonal-antibodies, Multiplex, Panitumumab-irdye800cw, Transport

Intercellular adhesion molecule-1 (ICAM-1) is a membrane protein whose expression is enhanced at pathological sites, supporting drug delivery using nanocarriers (NCs). Any of its five extracellular domains (D1 to D5) can be targeted, yet most NC studies have used antibody (Ab) R6.5, which targets domain D2. While this provided efficient NC targeting and intracellular transport, literature indicates the absence of D2 in about 50 % of ICAM-1 isoforms expressed in mouse models. In this study, we verified the presence of ICAM-1 isoforms lacking D2 in human cells at both mRNA and protein levels, supporting the need to test Abs targeting other ICAM-1 domains. We developed a new cell model specifically lacking ICAM-1 D2 and compared R6.5 to Abs targeting D1 (Ab 15.2), D3D4 (Ab G-5), and D5 (Ab H-4). Abs G-5 and H-4 showed best targeting results, for which they were coated on model polymeric NCs. Compared to non-specific IgG NCs, both anti-ICAM-1 formulations targeted recombinant cells expressing human ICAM-1 lacking D2 and also primary cells naturally expressing the whole ICAM-1 isoform pattern observed. Both formulations were efficiently internalized by cells and trafficked to lysosomes, as previously observed for ICAM-1-targeting systems. Furthermore, NCs coated with either one of these two Abs showed good cross-species reactivity, being amenable for future pre-clinical testing. Therefore, Abs G-5 or H-4 are good options to provide ICAM-1 targeting without missing ICAM-1 isoforms lacking D2, present in human.

JTD Keywords: Adhesion molecule-1 icam-1, Anti-icam-1 antibody, Antibody-targeted nanocarriers, Design, Different receptor epitopes, Domai, Endothelial delivery, Enlimomab, Icam-1 extracellular domains, Icam-1 isoforms, Identification, Intercellular adhesion molecule 1, Monoclonal-antibodies, Nanoparticles, Targeting and endocytosi, Transport