In:
Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 37, No. 15_suppl ( 2019-05-20), p. e14137-e14137
Abstract:
e14137 Background: HLA open conformers (OC) are defined as HLA class I molecules lacking beta-2-microglobulin (β2m) and peptide. OC can be derived from different HLA I molecules such as HLA-B27, -B57, and –Cw08. OC have a different three dimensional structure when compared to their respective HLA/β2m/peptide counterpart and induce distinct immunological processes by binding to LILRB and KIR molecules, both key receptors of the innate immune system. B57 OC expression is associated with enhanced immunity against viruses and can cause autoimmunity. Its potential anti-tumor activity has not been exploited so far. Methods: B57 OC and control molecules were expressed as IgG4 fusion proteins in CHO cells. The affinity for protein-ligand interaction was measured by surface plasmon resonance (SPR). Human macrophages M1/M2, phagocytosis and NK cytotoxicity were assessed by flow cytometry and cellular assays. Syngeneic pancreatic cancer (Pan02) or colon cancer (MC38) mouse models were used. Mice with tumors of 80mm 3 were treated twice weekly at 5 mg/kg. Tumor and blood samples were analysed. FDA cancer panels were assessed by IHC for LILRB1-5 expression. Results: B57 OC displays distinct protein-ligand interactions with high affinity binding to LILRB2 & 4, KIR2L1-3, and KIR3DL1. Therapeutic efficacy in pancreatic and colon cancer models was observed with monotherapy (p 〈 0.01), and combo therapy using PD1 and/or 41BB antibodies (p 〈 0.0001). Ex vivotumor sample analysis revealed a significant reduction of MDSC & Tregs, and an increase of M1 type macrophages. In addition, loss of MDSC functionality and enhanced CD8+ T cell expansion was noticed. IHC of human tissue demonstrated enhanced LILRB2 expression, notably in colon and lung cancer. Conclusions: B57 OC has a unique binding profile to LILRB and KIR receptors. B57 OC induces anti-tumor activity in diverse syngeneic mouse models and acts synergistically with PD1 or 41BB antibodies. Pre-clinical and human in vitroexperiments demonstrate that B57 OC mode of action is established with inhibition of MDSCs, macrophage polarization to M1 phenotype, activation of NK cells and LILRB blockade on tumor cells, which in turn support the adaptive immune system by increasing CD8+ effector T cells and reducing Treg numbers. B57 OC is a first-in-class therapeutic with robust anti-tumor activity.
Type of Medium:
Online Resource
ISSN:
0732-183X
,
1527-7755
DOI:
10.1200/JCO.2019.37.15_suppl.e14137
Language:
English
Publisher:
American Society of Clinical Oncology (ASCO)
Publication Date:
2019
detail.hit.zdb_id:
2005181-5
