The role of chimeric antigen receptor T cells targeting more than one antigen in the treatment of B-cell malignancies

Several products containing chimeric antigen receptor T cells targeting CD19 (CART19) have been approved for the treatment of patients with relapsed/refractory non-Hodgkin's lymphoma (NHL) and acute lymphoblastic leukaemia (ALL). Despite very impressive response rates, a significant percentage of patients experience disease relapse and die of progressive disease. A major cause of CART19 failure is loss or downregulation of CD19 expression in tumour cells, which has prompted a myriad of novel strategies aimed at targeting more than one antigen (e.g. CD19 and CD20 or CD22). Dual targeting can the accomplished through co-administration of two separate products, co-transduction with two different vectors, bicistronic cassettes or tandem receptors. In this manuscript, we review the pros and cons of each strategy and the clinical results obtained so far.

Identification of cell surface targets for CAR-T cell therapies and antibody-drug conjugates in breast cancer

BACKGROUND

Two promising therapeutic strategies in oncology are chimeric antigen receptor-T cell (CAR-T) therapies and antibody-drug conjugates (ADCs). To be effective and safe, these immunotherapies require surface antigens to be sufficiently expressed in tumors and less or not expressed in normal tissues. To identify new targets for ADCs and CAR-T specifically targeting breast cancer (BC) molecular and pathology-based subtypes, we propose a novel in silico strategy based on multiple publicly available datasets and provide a comprehensive explanation of the workflow for a further implementation.

METHODS

We carried out differential gene expression analyses on The Cancer Genome Atlas BC RNA-sequencing data to identify BC subtype-specific upregulated genes. To fully explain the proposed target-discovering methodology, as proof of concept, we selected the 200 most upregulated genes for each subtype and undertook a comprehensive analysis of their protein expression in BC and normal tissues through several publicly available databases to identify the potentially safest and viable targets.

RESULTS

We identified 36 potentially suitable and subtype-specific tumor surface antigens (TSAs), including fibroblast growth factor receptor-4 (FGFR4), carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), GDNF family receptor alpha 1 (GFRA1), integrin beta-6 (ITGB6) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). We also identified 63 potential TSA pairs that might be appropriate for co-targeting strategies. Finally, we validated subtype specificity in a cohort of our patients, multiple BC cell lines and the METABRIC database.

CONCLUSIONS

Overall, our in silico analysis provides a framework to identify novel and specific TSAs for the development of new CAR-T and antibody-based therapies in BC.

Syncytia formation affects the yield and cytotoxicity of an adenovirus expressing a fusogenic glycoprotein at a late stage of replication

Fusogenic membrane glycoproteins (FMGs) may enhance the cytotoxicity of conditionally replicative adenoviruses. However, expression at early stages of infection impairs virus replication. We have inserted the hyperfusogenic form of the gibbon ape leukemia virus (GALV) envelope glycoprotein as a new splice unit of the major late promoter (MLP) to generate a replication-competent adenovirus expressing this protein. At high multiplicity of infection (MOI), this virus replicated efficiently forming clumps of fused cells and showing a faster release. In contrast, at low MOI, infected cells formed syncytia where only one nucleus contained virus DNA, decreasing total virus production but increasing cytotoxicity.