Epstein-Barr Virus Viral Loads and Serum Free Light Chains Levels Are Diagnostic Markers of Lymphoma in HIV-Infected Patients

Introduction

Epstein-Barr virus (EBV) viral load and serum free light chains (sFLC) are easily measurable and are possible biomarkers for screening and prognosis in HIV-related lymphomas. EBV load and sFLC levels have been shown to be increased at the diagnosis of HIV-related lymphomas but there is a lack of data on their levels at complete response (CR). We aimed to determine the clinical relevance and the potential use of combining EBV load and sFLC measurements as tumor markers in patients with HIV-related lymphomas.

Methods

Retrospective study of HIV-infected patients diagnosed with non-Hodgkin (NHL) and Hodgkin’s lymphoma (HL) treated in a single institution from 1998 to 2012. EBV loads were determined in plasma by means of a commercial real-time PCR technique (EBV PCR kit, Qiagen GmbH, Hilden, Germany). Levels of κ and λ sFLC were measured in serum using a standardized assay (FREELITE, The Binding Site, Birmingham, UK). sFLC were considered elevated when κ, λ, or the sum of κ and λ were above the upper normal limit. Clinical and biological data were collected from the clinical records.

Results

Sixty-eight patients were studied (53 NHL and 15 HL). At diagnosis (N=47), levels of κ, λ, and sum of κ and λ sFLC were elevated in 87%, 70%, and 81% of patients, respectively. At CR (N=29), the percentage of patients with elevated κ, λ, and κ+λ was 79%, 45%, and 62%, respectively. EBV load was detectable in 60% of the patients at diagnosis (N=50) and in 7.4% at CR (N=27). Median levels of κ, λ, and κ+λ sFLC at diagnosis were higher than at CR (6.06 mg/dL vs 3.19 mg/dL, P=0.006; 3.94 mg/dL vs 2.21 mg/dL, P=0.021; 11.38 mg/dL vs 5.43 mg/dL, P=0.004; respectively). Median levels of EBV loads at diagnosis were also higher than at CR (121.5 copies/mL vs. 0 copies/mL, P<0.001). There were fewer patients with elevated λ and κ+λ levels and detectable EBV loads at CR than at diagnosis (P=0.028, P=0.071 and P<0.001); respectively).

Detectable EBV loads were associated with elevated λ (P=0.023) and κ+λ levels (P=0.055). Among the cases with detectable EBV load, 76% had elevated λ levels and 86% had elevated κ+λ levels. Moreover, median levels of κ and of κ+λ were higher in patients with detectable EBV loads than in patients with undetectable EBV loads (7.56mg/dL vs. 3.23 mg/dL, P=0.012 and 12.91mg/dL vs. 5.48mg/dL, P=0.022; respectively).

EBV load and levels of sFLC were compared between groups defined by the clinical-biological features. At diagnosis, more patients with AIDS criteria before lymphoma showed increased λ sFLC than patients without AIDS criteria before lymphoma and the median levels of λ were higher in the group of patients with previous AIDS criteria. EBV loads were higher in patients without AIDS criteria before lymphoma. Patients with detectable HIV loads showed higher levels of λ than patients with undetectable HIV loads. However, all the former differences only showed a trend without reaching statistical significance.

At CR, median level of λ sFLC was higher in patients who presented Bulky disease at diagnosis than in patients without Bulky (P=0.077). The median levels of κ, λ and κ+λ at CR were higher in patients with detectable HIV loads at diagnosis than in those with undetectable loads (P=0.032, P=0.064 and P=0.045; respectively). All 4 patients with undetectable HIV loads had normal κ+λ levels at CR. Unlike, only 6 out of 21 patients with detectable HIV loads had normal κ+λ levels (P=0.017) at CR. Patients treated with combination antiretroviral therapy (cART) before lymphoma presented lower κ levels at CR than patients not previously treated with cART (P=0.081). Also, increased κ and λ levels at CR were more frequently found in patients not treated with cART before lymphoma than in those previously treated (κ= 93% vs. 64%, P=0.080 and λ= 60% vs. 29%, P=0.089).

Neither elevated sFLC levels nor positive EBV loads at diagnosis had impact on overall survival, progression-free survival or disease-free survival.

Conclusions

In patients with HIV-related lymphomas detectable EBV loads were associated with higher sFLC levels. At lymphoma diagnosis both sFLC levels and EBV loads were higher than at CR pointing they may be used as lymphoma markers. The control of HIV-infection was related to lower sFLC levels both at diagnosis and at CR.

This work was supported in part by grants EC11-041 and RD12/0036/0029 RTICC from “Instituto Carlos III” Spain and 2014 SGR225 (GRE) from Generalitat de Catalunya, and by Josep Carreras International Foundation.