CD30(+)OX40(+) Treg is associated with improved overall survival in colorectal cancer

Regulatory T cells (Tregs) are often enriched in tumors, where their immunosuppressive function has a key role in tumor persistence and progression. In colorectal cancer (CRC), however, Tregs are frequently associated with an improved clinical outcome. Tumor-infiltrating Tregs have been shown to exhibit a distinct signature comprising the co-stimulatory molecules (OX40, 4-1BB), cytokine receptors (IL1R2, IL21R, CCR8, CD30), and co-inhibitory molecules (PD-L1, TIGIT). Here, we showed by flow cytometry that circulating CD45RO(+) Tregs from patients with CRC (n = 25) have elevated CD30 and OX40 expression compared to healthy subjects (n = 14). We identified co-expression of CD30 and OX40 on circulating CD45RO(+) Tregs using single-cell images captured by the DEPArray(™) system. The frequency of CD30(+)OX40(+)CD45RO(+) Tregs was significantly higher in CRC patients than in healthy subjects (P < 0.001). Importantly, receiver operating characteristic analysis confirmed that this CD30(+)OX40(+) Treg subset could strongly discriminate between CRC patients and healthy subjects with the highest accuracy of 92.3%, an AUC of 0.92, a sensitivity of 88%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 82.35%, and a trade-off value of 3.44%, compared to other Treg subsets. Consistently, multiplex-IHC/IF of tumor-infiltrating Tregs revealed a significant association between high densities of CD30(+)OX40(+) Tregs and improved overall survival; no such association was found for other subsets. These data suggest a potential role for CD30(+)OX40(+) Tregs as a diagnostic or prognostic biomarker in CRC. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00262-021-02859-x.