Effects of cyclophosphamide and IL-2 on regulatory CD4+ T cell frequency and function in melanoma patients vaccinated with HLA-class I peptides: impact on the antigen-specific T cell response

Abstract

The frequency and function of regulatory T cells (Tregs) were studied in stage II–III melanoma patients who were enrolled in a phase II randomized trial of vaccination with HLA-A*0201-modified tumor peptides versus observation. The vaccinated patients received low-dose cyclophosphamide (CTX) and low-dose interleukin-2 (IL-2). Tregs were analyzed in the lymph nodes (LNs) of stage III patients who were undergoing complete lymph node dissection and in peripheral blood mononuclear cells (PBMCs) collected before vaccination and at different time points during the vaccination period. The LNs of the vaccinated patients, which were surgically removed after two rounds of vaccination and one dose of CTX, displayed a low frequency of Tregs and a less immunosuppressive environment compared with those of the untreated patients. The accurate time-course analysis of the PBMCs of patients enrolled in the vaccination arm indicated a limited and transient modulation in the frequencies of Tregs in PBMCs collected after low-dose CTX administration and a strong Treg boost in those PBMCs collected after low-dose IL-2 administration. However, a fraction of the IL-2-boosted Tregs was functionally modulated to a Th-1-like phenotype in the vaccinated patients. Moreover, low-dose IL-2 promoted the concomitant expansion of conventional activated CD4+ T cells. Despite the amplification of Tregs, IL-2 administration maintained or further increased the number of antigen-specific CD8+ T cells that were induced by vaccination as demonstrated by the ex vivo human leukocyte antigen-multimer staining and IFN-γ ELISpot assays. Our study suggests that the use of CTX as a Treg modulator should be revised in terms of the administration schedule and of patients who may benefit from this drug treatment. Despite the Treg expansion that was observed in this study, low-dose IL-2 is not detrimental to the functional activities of vaccine-primed CD8+ T cell effectors when used in the inflammatory environment of vaccination.Electronic supplementary materialThe online version of this article (doi:10.1007/s00262-013-1397-7) contains supplementary material, which is available to authorized users.

Convergences and Divergences of Thymus- and Peripherally Derived Regulatory T Cells in Cancer

“…For instance, circulating T reg from melanoma patients showed significantly higher IFN-γ secretion following a protocol of tumor peptide vaccination plus IL-2 and cyclophosphamide, in line with enhanced serum IL-12 (158). On the whole, these data suggest that, especially in the human system, the transition from T-bet + T reg , specialized Th1 suppressors, into T-bet + IFN-γ + T reg , Th1-like plastic cells, may not only depend on the availability and the responsiveness to exogenous stimuli, but may differentially occur in distinct T reg precursors: on the one side, tT reg , enriched in committed and self-specific cells, may be forced to arrest to the specialization (T-bet + ) endpoint; on the other side, pT reg , containing less committed and foreign antigens-specific cells, may be more prone to the complete reprograming into pro-inflammatory (T-bet + IFN-γ + ) cells.…”

The importance of correctly timing cancer immunotherapy

“…In a randomized phase II trial, administration of a single dose of cyclophosphamide, followed by vaccination 3 days later with IMA901, a vaccine that consists of multiple-tumor associated peptides (TUMAPs) plus granulocyte-macrophage colony-stimulating factor (GM-CSF), reduced the number of Tregs and was associated with prolonged survival in immune responder patients with advanced renal cell cancer [52]. Similarly, peripheral blood mononuclear cells (PBMCs) analysis of stage II-III melanoma patients, who were vaccinated with HLA-A*0201-modified tumor peptides 7 days after low-dose of cyclophosphamide, showed transient reduction in the frequency of Tregs and an increase in vaccine-induced antigen specific CD8 + T-cells [50]. Other studies in which cyclophosphamide treatment was used, showed that the depletion of Tregs may be associated with the induction of Th17, Th1 and vaccine-induced CD25 + CD4 + Foxp3-negative effector T-cells [65,66].…”

“…Several studies suggest that the optimal time point for vaccination is 3-7 days after this type of chemotherapy [50][51][52]. In a randomized phase II trial, administration of a single dose of cyclophosphamide, followed by vaccination 3 days later with IMA901, a vaccine that consists of multiple-tumor associated peptides (TUMAPs) plus granulocyte-macrophage colony-stimulating factor (GM-CSF), reduced the number of Tregs and was associated with prolonged survival in immune responder patients with advanced renal cell cancer [52].…”

Vaccination in Human Solid Tumors: Recent Progress in the Clinical Arena

“…A recent adjunct to the plethora of escape mechanisms is the infl ammasome component Nirp3 underlining the complex relationship between infl ammation and cancer [ 27 ] that impairs vaccine-induced immunity. However, one should consider that several mechanisms may be activated by tumor cells either simultaneously or one after the other according to modifi cations that occur in the tumor microenvironment and in different tissues in which tumor cells are growing even during different types of therapy [ 28 ]. A recent additional mechanism of tumor escape has been described that includes tumor cell secretion of sterol metabolites (LXR ligands), which inhibit the expression of CCR7 on the cell surface of dendritic cells (DCs), thereby disrupting DC migration to the lymph nodes and dampening the antitumor immune priming event [ 29 ].…”