Thioredoxin-1 as a biological predictive marker for selecting diffuse large B-cell lymphoma patients for etoposide-containing treatment.

OBJECTIVE: In diffuse large B-cell lymphoma (DLBCL), there is an unmet medical need to select patients who would benefit from intensified frontline treatments such as adding etoposide to an R-CHOP regimen. METHODS: The present work included a retrospective clinical analysis of two patient cohorts and an in vitro study. Primary biopsy samples from DLBCL patients treated with an etoposide-containing high-dose regimen (n = 37) and etoposide-containing frontline treatment (n = 69, R-CHOEP) were studied using immunohistochemical thioredoxin-1 (Trx1) staining. Two DLBCL cell lines expressing Trx1 were cultured, and their expression was silenced using the small interfering RNA knockdown technique. Chemoresistance was tested with doxorubicin, etoposide, vincristine, prednisolone and carboplatin. RESULTS: Thioredoxin-1 knockdown sensitised DLBCL cells to doxorubicin (P < .0001) but decreased etoposide-induced cell death (P < .00001). In DLBCL patients who received etoposide-containing frontline treatment, low cytoplasmic Trx1 expression was associated with inferior 5-year overall survival (46% vs 76%, P = .026) and disease-specific survival (68% vs 90%, P = .026). CONCLUSIONS: Strong Trx1 expression appears to increase drug resistance to doxorubicin but sensitises cells to etoposide. This implies that Trx1 expression might be the first predictive biological marker to select the patients who might benefit from adding etoposide to R-CHOP immunochemotherapy.

Peroxiredoxin 6 Serum Levels and Risk of Neutropenic Infections in Diffuse Large B-cell Lymphoma.

BACKGROUND/AIM: Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy where antioxidant enzyme peroxiredoxin 6 (Prx6) has previously been associated with adverse outcomes. Its systemic effects in DLBCL are unknown. MATERIALS AND METHODS: This study included 53 patients with DLBCL, five patients with primary central nervous system lymphoma (PCNSL) and 20 healthy controls. The expression of Prx6 was evaluated immunohistochemically in DLBCL tissue samples and compared to its expression in blood serum. RESULTS: Prx6 expression was the highest in healthy controls, followed by DLBCL patients and PCNSL patients. Febrile neutropenic infection after the first treatment course was associated with low pre-treatment Prx6 serum levels (<14 ng/ml) (p=0.025, OR=8.615, 95% confidence interval=1.032-71.933). Serum levels of Prx6 recovered after treatment (p=0.006). CONCLUSION: Patients with low Prx6 levels might be more prone to treatment-related adverse effects through elevated levels of oxidative stress.

Nuclear factor erythroid 2-related factors 1 and 2 are able to define the worst prognosis group among high-risk diffuse large B cell lymphomas treated with R-CHOEP.

AIMS: Oxidative stress markers and antioxidant enzymes have previously been shown to have prognostic value and associate with adverse outcome in patients with diffuse large B cell lymphoma (DLBCL). Nuclear factor erythroid 2-related factor 1 (Nrf1) and factor 2 (Nrf2) are among the principal inducers of antioxidant enzyme production. Kelch ECH associating protein 1 (Keap1) is a negative regulator of Nrf2, and BTB (BR-C, ttk and bab) domain and CNC homolog 1 (Bach1) represses the function of both factors. Their significance in DLBCL prognosis is unknown. METHODS: Diagnostic biopsy samples of 76 patients with high-risk DLBCL were retrospectively stained with immunohistochemistry for Nrf1, Nrf2, Keap1 and Bach1, and correlated with clinical data and outcome. RESULTS: Nuclear Nrf2 and nuclear Bach1 expression were associated with adverse clinical features (anaemia, advanced stage, high IPI, high risk of neutropaenic infections), whereas cytoplasmic Nrf1 and Nrf2 were associated with favourable clinical presentation (normal haemoglobin level, no B symptoms, limited stage). None of the evaluated factors could predict survival alone. However, when two of the following parameters were combined: high nuclear score of Nrf2, low nuclear score of Nrf1, high cytoplasmic score of Nrf1 and low cytoplasmic score of Keap1 were associated with significantly worse overall survival. CONCLUSIONS: Nrf1 and Nrf2 are relevant in disease presentation and overall survival in high-risk DLBCL. Low nuclear expression of Nrf1, high cytoplasmic expression of Nrf1, high nuclear expression of Nrf2 and low cytoplasmic expression of Keap1 are associated with adverse outcome in this patient group.

Total peroxiredoxin expression is associated with survival in patients with follicular lymphoma.

Redox state-regulating enzymes may have roles in chemoresistance and also in lymphomagenesis, but there have been only a limited number of studies on this topic in lymphomas. Our aim was to assess expression of the redox state-regulating enzymes peroxiredoxins (Prxs) I-VI and thioredoxin (Trx) and the oxidative stress marker nitrotyrosine in follicular lymphomas (FLs). We immunohistochemically assessed Prxs I-VI, Trx and nitrotyrosine in a cohort of 76 histologically confirmed, untreated FLs. We also studied the localisation of Prxs I, II, III, V and VI by means of immunoelectron microscopy (IEM). Immunohistochemistry results were correlated with disease-specific survival (DSS), progression-free survival (PFS), overall survival (OS) and clinical prognostic factors. When all Prx expression intensities were grouped as a single variable, we discovered that high total Prx intensity correlated with favourable DSS (p = 0.024) and OS (p = 0.035) but not with PFS. No deaths due to lymphoma were recorded amongst patients with high total Prx expression during the median follow-up period of 7.6 years. IEM results were in line with earlier ones demonstrating wide subcellular localisation of Prx isoenzymes. In conclusion, our results demonstrate an association between high total Prx expression and prolonged survival and suggest that Prxs may have a protective role in FL that cannot be compensated by other antioxidant mechanisms.

High intensity of cytoplasmic peroxiredoxin VI expression is associated with adverse outcome in diffuse large B-cell lymphoma independently of International Prognostic Index.

AIMS: Diffuse large B-cell lymphoma (DLBCL) is an aggressive and potentially fatal disease. Prediction of risk of relapse is based on clinical markers. There is a need for more accurate biomarkers to select patients for more aggressive first-line treatments. Peroxiredoxins (Prxs) are a family of potent antioxidant proteins. Their prognostic role in DLBCL is unknown. METHODS: Altogether, 103 diagnostic biopsy samples from patients with DLBCL were immunohistochemically stained for Prxs I, II, III, V and VI. RESULTS: Strong Prx VI expression was associated with the presence of B-symptoms. There were no other significant associations with traditional risk factors. Five-year disease-specific survival was 68.6% in patients with high cytoplasmic Prx VI intensity vs 97.0% in those with low intensity. In multivariate analysis, high Prx VI expression (HR 12.846, 95% CI 1.722 to 95.807, p=0.013) was an independent risk factor of lymphoma-associated death not related to International Prognostic Index score (HR 2.514, 95% CI 1.040 to 6.073, p=0.041). CONCLUSIONS: High intensity of cytoplasmic Prx VI expression in pretreatment DLBCL samples predicts worse outcome in patients with DLBCL. Whether Prx VI is associated with chemoresistance, and therefore a poorer outcome, needs to be evaluated. If Prx VI is a predictive marker and it proves causality, it would be crucial to study Prx VI ability to become a target enzyme for treatment.

Antithrombin III is probably not a suitable biomarker for diagnosis of primary central nervous system lymphoma.

Antithrombin III (AT III) in cerebrospinal fluid (CSF) has been suggested to have high specificity and sensitivity in separating primary central nervous system (CNS) lymphoma from other neurological conditions. We measured with ELISA CSF and serum AT III and albumin levels in 12 lymphoma patients with CNS involvement, 30 lymphoma patients without CNS involvement, and 41 patients with non-neoplastic neurological diseases. AT III immunostaining was also carried out, in lymphoma patients. Both CSF AT III and albumin levels were higher in lymphoma patients with CNS involvement. AT III/albumin ratio in CSF was the most sensitive and specific measure for diagnosis. Lowest it was in patients with known CNS lymphoma. Serum AT III levels were lower both in CNS lymphoma and systemic lymphoma. CSF AT III levels were shown to be higher in lymphoma patients with CNS involvement, when AT III/albumin ratios were lower. This was probably a result of lowered serum AT III levels, indicating that high levels of AT III in CSF might reflect only leakage of the blood-brain barrier. Thus, AT III fails to be a specific marker for diagnosis of lymphoma CNS involvement.