Journal Article

CEA expression heterogeneity and plasticity confer resistance to the CEA-targeting bispecific immunotherapy antibody cibisatamab (CEA-TCB) in patient-derived colorectal cancer organoids

Bryant, Annette, Starling, Naureen, Khan, Khurum, Semiannikova, Maria, Griffiths, Beatrice, Matthews, Nik, von Loga, Katharina, Fotiadis, Nicos, Spain, Georgia, Thomas, Janet, Cunningham, David, Gonzalez-Exposito, Reyes, Powles, Thomas, Guettler, Sebastian, Gerlinger, Marco, Patel, Radhika, Chau, Ian, Woolston, Andrew, Ranes, Michael, Melcher, Alan, Watkins, David, Saffery, Claire, Mansfield, David, Barber, Louise J., Rao, Sheela, Challoner, Ben, Wallberg, Fredrik, Swain, Amanda

2019

Overview

Background The T cell bispecific antibody cibisatamab (CEA-TCB) binds Carcino-Embryonic Antigen (CEA) on cancer cells and CD3 on T cells, which triggers T cell killing of cancer cell lines expressing moderate to high levels of CEA at the cell surface. Patient derived colorectal cancer organoids (PDOs) may more accurately represent patient tumors than established cell lines which potentially enables more detailed insights into mechanisms of cibisatamab resistance and sensitivity. Methods We established PDOs from multidrug-resistant metastatic CRCs. CEA expression of PDOs was determined by FACS and sensitivity to cibisatamab immunotherapy was assessed by co-culture of PDOs and allogeneic CD8 T cells. Results PDOs could be categorized into 3 groups based on CEA cell-surface expression: CEA hi ( n  = 3), CEA lo ( n  = 1) and CEA mixed PDOs ( n  = 4), that stably maintained populations of CEA hi and CEA lo cells, which has not previously been described in CRC cell lines. CEA hi PDOs were sensitive whereas CEA lo PDOs showed resistance to cibisatamab. PDOs with mixed expression showed low sensitivity to cibisatamab, suggesting that CEA lo cells maintain cancer cell growth. Culture of FACS-sorted CEA hi and CEA lo cells from PDOs with mixed CEA expression demonstrated high plasticity of CEA expression, contributing to resistance acquisition through CEA antigen loss. RNA-sequencing revealed increased WNT/β-catenin pathway activity in CEA lo cells. Cell surface CEA expression was up-regulated by inhibitors of the WNT/β-catenin pathway. Conclusions Based on these preclinical findings, heterogeneity and plasticity of CEA expression appear to confer low cibisatamab sensitivity in PDOs, supporting further clinical evaluation of their predictive effect in CRC. Pharmacological inhibition of the WNT/β-catenin pathway may be a rational combination to sensitize CRCs to cibisatamab. Our novel PDO and T cell co-culture immunotherapy models enable pre-clinical discovery of candidate biomarkers and combination therapies that may inform and accelerate the development of immuno-oncology agents in the clinic.

• Publisher: BioMed Central,BioMed Central Ltd,BMJ Publishing Group LTD,BMJ Publishing Group
• Subject: Antibodies / Antibodies, Bispecific - pharmacology / Antibodies, Bispecific - therapeutic use / Antigens / Antineoplastic Agents, Immunological - pharmacology / Antineoplastic Agents, Immunological - therapeutic use / Binding sites / Biological markers / Biomarkers / Biopsy / Cancer / Cancer cells / Cancer metastasis / Cancer patients / Cancer therapies / Carcinoembryonic antigen / Carcinoembryonic Antigen - genetics / Care and treatment / CD8-Positive T-Lymphocytes / CEA / Chemotherapy / Cibisatamab / Clinical/Translational Cancer Immunotherapy / Coculture Techniques / Colorectal cancer / Colorectal Neoplasms - drug therapy / Colorectal Neoplasms - genetics / Colorectal Neoplasms - pathology / Cytotoxicity / Drug dosages / Drug Resistance, Neoplasm - genetics / Drug Screening Assays, Antitumor / Ethics / Flow cytometry / Gene Expression Regulation, Neoplastic / Genetic Heterogeneity / GPI-Linked Proteins - antagonists & inhibitors / GPI-Linked Proteins - genetics / Growth factors / Humans / Immunology / Immunotherapy / Kinases / Lymphocytes / Medicine / Medicine & Public Health / Metastasis / Microbial drug resistance / Mutation / Novels / Oncology / Patient-derived organoids / Patients / Regorafenib / Research Article / RNA / T cell receptors / T cells / Tissue Culture Techniques / Trifluridine / Tumors / Vascular endothelial growth factor / WNT/β-catenin