Tumor cells expressing phosphoantigens and stress ligands

Tumor cells expressing phosphoantigens and stress ligands represent a specific metabolic and physiological state of malignancy that is selectively recognized by the innate-like immune system, particularly Vγ9Vδ2 T cells. Phosphoantigens, such as isopentenyl pyrophosphate (IPP), are intermediate metabolites of the mevalonate pathway that accumulate in cancer cells due to metabolic dysregulation or pharmacological intervention with aminobisphosphonates (D'Asaro et al., 2010). These phosphoantigens are not presented by MHC molecules but instead interact with the intracellular domain of Butyrophilin 3A1 (BTN3A1), which, in coordination with Butyrophilin 2A1 (BTN2A1), triggers the activation of the Vγ9Vδ2 T-cell receptor (Gu et al., 2020). Additionally, these tumor cells often overexpress stress-induced ligands like MICA, MICB, and ULBPs, which serve as signals recognized by the NKG2D activating receptor on NK cells and various T-cell subsets (Groh et al., 1999). Therapeutic strategies targeting this phenotype include the use of bisphosphonates to sensitize cells, monoclonal antibodies to stabilize the BTN3A complex (e.g., ICT01), and adoptive transfer of gamma-delta T cells. This multi-ligand target profile allows for the preferential elimination of transformed cells while sparing healthy tissue that lacks these specific metabolic abnormalities and stress markers.

Other names

Phosphoantigen-presenting tumor cellsStress-ligand-expressing cancer cellsVγ9Vδ2 T-cell-susceptible tumor cellsMetabolically dysregulated tumor cells

Activation of Vγ9Vδ2 T cells through the recognition of phosphoantigens (e.g., IPP) presented by the Butyrophilin 3A1 (BTN3A1) and Butyrophilin 2A1 (BTN2A1) complex, often enhanced by costimulatory signals from stress ligands (e.g., MICA/B) interacting with the NKG2D receptor (Gu et al., 2020; Rigau et al., 2020).