Psoralen plus ultraviolet A ± interferon-α treatment resistance in mycosis fungoides: the role of tumour microenvironment, nuclear transcription factor-κB and T-cell receptor pathways

BACKGROUND Interferon (IFN)-alpha is widely used in the treatment of mycosis fungoides (MF) and when used in combination with photochemotherapy (psoralen plus ultraviolet A, PUVA) both improved response and duration of complete remission have been reported. However, in spite of encouraging results of the initial studies, currently there is no information available on specific prognostic factors enabling prediction of patients' resistance to PUVA +/- IFN-alpha treatment. OBJECTIVES To identify factors responsible for resistance to PUVA +/- IFN-alpha treatment in MF patients. PATIENTS/METHODS The gene expression profiling of pretreatment samples from 29 patients diagnosed as IA, IB or IIA stage of MF enrolled in a randomized PUVA vs. PUVA + IFN-alpha clinical trial was analysed using cDNA microarrays. A Cox model (SAM) and gene set enrichment analysis (GSEA) were used for identification of genes and biologically significant pathways related to resistance to treatment. RESULTS Genes involved in NF-kappaB signalling, T-cell receptor (TCR) signalling, cytokine signalling and proliferation were differentially expressed between responders and nonresponders. Interestingly, expression of markers representative of those pathways was found not only in the tumoral cells, but also in specific subpopulations of macrophages, dendritic cells and other non-neoplastic cell types constituting the tumour microenvironment, likely involved in the promotion of survival and proliferation of cutaneous T-cell lymphoma. CONCLUSIONS Gene expression changes in both the tumour and the tumour microenvironment are an important determinant of treatment outcome in early-stage MF patients. Some proinflammatory factors such as NF-kappaB, inflammatory cytokines and their receptors in addition to TCR-associated molecules could be promising targets for MF treatment.