Supplementary Figure Legends - word editable file

Supplementary Methods - word editable file

Word document for Supplementary Table 1

Background:Production of chimeric antigen receptor T cell (CAR-T) therapies depends on antibody reagents to label, isolate, and expand T cell products. We sought to create antibody tools specific for the variable domain of heavy-chain only antibodies (VHHs), also known as nanobodies, used in some CARs. Methods:We immunized a mouse with VHH and selected two murine monoclonal antibodies (mAbs) that bind to distinct epitopes in conserved framework regions of llama-derived VHHs, and not to human VH domains. Anti-VHH mAbs were characterized by enzyme-linked immunosorbent assay, surface plasmon resonance, and hydrogen-deuterium exchange mass spectrometry; were then tested for cell/tissue labeling and for modulating cellular activity in VHH-CAR-T cells. Results:We produced a high-quality dual-clonal anti-VHH antibody product and confirmed reactivity to over 98% of VHH proteins regardless of their antigenic specificity, with no reactivity to human or mouse IgG and reduced reactivity to conventional llama or alpaca IgG. Anti-VHH binding did not disrupt VHH/antigen interaction, and thus was appropriate for secondary labeling to assess cellular or tissue reactivity of VHH molecules. Despite not interfering with antigen binding, anti-VHH antibodies (Abs) potently blocked VHH-CAR-T activation and cytolytic killing of target cells. When immobilized, anti-VHH Abs induced strong activation and expansion of VHH CAR-T cells; with 730-fold mean expansion, >94% CAR purity, and retained CD8/CD4 heterogeneity. Functionally, anti-VHH antibody-expanded CAR-T cells maintained strong antigen-specific activity without functional exhaustion. Conclusions:Overall, these data identify useful anti-VHH mAbs that can be applied to better understand and manipulate VHH-based CAR-T cells or other VHH-based immunotherapies.

We have previously demonstrated that Claudin-2 is required for colorectal cancer (CRC) liver metastasis. The expression of Claudin-2 in primary CRC is associated with poor survival and highly expressed in liver metastases. Claudin-2 also promotes breast cancer liver metastasis by enabling seeding and cancer cell survival. These observations support Claudin-2 as a potential therapeutic target for managing patients with liver metastases. Antibody-drug conjugates (ADC) are promising antitumor therapeutics, which combine the specific targeting ability of monoclonal antibodies with the potent cell killing activity of cytotoxic drugs. Herein, we report the generation of 28 anti-Claudin-2 antibodies for which the binding specificities, cross-reactivity with claudin family members, and cross-species reactivity were assessed by flow cytometry analysis. Multiple drug conjugates were tested, and PNU was selected for conjugation with anti-Claudin-2 antibodies binding either extracellular loop 1 or 2. Anti-Claudin-2 ADCs were efficiently internalized and were effective at killing Claudin-2-expressing CRC cancer cells in vitro. Importantly, PNU-conjugated-anti-Claudin-2 ADCs impaired the development of replacement-type CRC liver metastases in vivo, using established CRC cell lines and patient-derived xenograft (PDX) models of CRC liver metastases. Results suggest that the development of ADCs targeting Claudin-2 is a promising therapeutic strategy for managing patients with CRC liver-metastatic disease who present replacement-type liver metastases.