Indoleamine 2,3-dioxygenase (IDO) is an intracellular enzyme that mediates the metabolism of the essential amino acid L-tryptophan into immunosuppressive metabolites, such as kynurenine and 3-hydroxyanthranilic acid. IDO is a key factor maintaining immune tolerance, and is overexpressed in several human cancers: prostate, breast, brain, and hematologic malignancies. Mechanisms leading to expression of IDO in human tumors are still unknown. Our study aims to investigate the role of IDO expression in clinical behavior of diffuse large B-cell lymphoma (DLBCL).
The case group included 23 patients (6 males, 17 females) with DLBCL (median age: 48.5 years, range: 23-74). The patients were treated with R-CHOP/CHOP, CHOEP, R-DA-EPOCH. Remission was achieved in 52.1% of the cases and in 47.8% disease progression after treatment was continued. The relative mRNA expression levels of IDO were measured in pre-treatment tumour tissue specimens from DLBCL patients using qPCR analysis.
The mRNA expression of IDO was found in 11 cases (48%) and further this group was considered as IDO-positive. The presence of IDO expression was significantly associated with advanced stage of disease (p
Results suggest that IDO expression correlates with the disease progression and impaired clinical outcome in DLBCL patients. The presence of IDO expression in tumour tissue should be considered as an additional unfavorable prognostic risk factor to patients with DLBCL, especially for ABC subtype. It may represent a promising therapeutic target for DLBCL patients with resistance to chemotherapy. Ongoing studies from our group are currently evaluating the impact of immune escape checkpoints on patients' survival.
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All authors have declared no conflicts of interest.