Concomitant deletion of Shp-1 and Shp-2 in T cells fails to improve anticancer responses

Anticancer T cells acquire a dysfunctional state characterized by poor effector function and expression of inhibitory receptors, such as programmed cell death protein 1 (PD-1). Blockade of PD-1 signalling leads to T cell reinvigoration and is increasingly applied as an effective anticancer treatment. Recent work challenged the commonly held view that the phosphatase Src homology 2 (SH2) domain–containing phosphatase (SHP)-2 is essential for the molecular cascade downstream PD-1, suggesting functional redundancy with the homologous phosphatase SHP-1. Therefore, we investigated the effect of concomitant SHP-1 and 2 deletion in T cells by knocking out these phosphatases under the CD4cre promoter. In vivo results not only indicate that Shp-1/2 deletion is insufficient to ameliorate tumour control, but also that it impairs the therapeutic effects of anti-PD1 treatment, affecting tumour-infiltrating CD8+ T cells. Notably, acute deletion of Shp-1/2 in effector T cells also fails to improve tumour control. In vitro results show that Shp-1/2-deleted CD8+ T cells exhibit impaired expansion due to a survival defect and proteomics analysis reveals substantial alterations in their proteome, including in apoptosis-related pathways. This data indicates that concomitant ablation of SHP-1/2 in polyclonal T cells fails to improve their anticancer properties, implying that caution shall be taken when considering their inhibition for immunotherapeutic approaches.