Epstein-Barr virus reactivation is a potentially severe complication in chronic lymphocytic leukemia patients with poor prognostic biological markers and fludarabine refractory disease

Chronic lymphocytic leukemia (CLL) patients who are refractory to, or have early relapse after, fludarabine and cyclophosphamide (FC) based therapy have a poor prognosis.1 A major clinical problem in FC-refractory disease is a profound immunodeficiency, resulting in a high incidence of severe opportunistic infections.2 The immunodeficiency may be caused either by the natural history of high-risk fludarabine-refractory CLL disease in itself and/or immuno-suppressive side effects of the CLL treatment used for this group of patients. Over a two-year period, we identified 11 CLL patients with EBV-reactivation, defined as measurable EBV-DNA copies by quantitative PCR.

All 11 patients had IgG antibodies (VCA and/or EBNA) against EBV. Ten patients had negative CMV qPCR at the time of EBV-reactivation, while one (UPN 6) had concomitant CMV-reactivation. All 11 patients had biochemical signs of hypogammaglobulinemia, while 8 (UPN 1, 2, 5–6 and 8–11) patients had neutropenia. The median age at diagnosis of CLL was 58 years (range 43–75 years). The median time from CLL diagnosis to EBV-reactivation was 4.5 years (range 1–13 years). With a follow-up time of 824 days, the median overall survival from date of EBV-reactivation was 264 days, despite aggressive rituximab based chemo-immunotherapy in symptomatic cases. Eight deaths were observed, 3 as a direct result of EBV-reactivation.

All 11 patients had high-risk disease as defined by either IGVH mutational status and/or FISH analysis of recurrent cytogenetic aberrations associated with CLL (Table 1). Ten patients (UPN 1–2 and 4–11) had received fludarabine based treatment prior to EBV-reactivation, and 9 patients (UPN 1–2, 4–6 and 8–11) had fludarabine refractory disease at the time of EBV-reactivation. Whether these observations suggest that EBV-reactivation is associated with the immuno-suppressive side-effects caused by treatment of advanced CLL cannot be determined from our data set. However, we do note that EBV-reactivation occurred before exposure to alemtuzumab in 4 patients (UPN 1, 7–8 and 11), and in one patient (UPN 3) prior to any CLL treatment. This last patient turned out to be fludarabine-resistant, did not receive rituximab, but responded well to standard alemtuzumab treatment on which EBV-copies in sequential blood samples disappeared. Of the 4 patients not treated with alemtuzumab, one developed proven EBV-driven CLL-related BLPD, one hemophagocytic syndrome, one a possible BLPD and one did not have any symptoms.

The clinical presentation of the patients was related to the level of EBV copies/mL plasma.

Table 1.Characteristics of chronic lymphocytic leukemia patients with Epstein-Barr virus-reactivation.

EBV-reactivation in CLL patients has previously been observed in small patient cohorts. The largest study describes 5 patients with solitary BLPDs, 4 with CLL.3 All patients had received fludarabine, and 3 alemtuzumab. The lesions were clonally distinct from the original low-grade B-cell neoplasm in 3 out of 4 cases assessed. Two single case studies report on patients treated with fludarabine who develop EBV-reactivation in addition to other events.4,5 A larger prospective study describes 4 cases of EBV-reactivation during FC therapy in 24 patients with low-grade non-Hodgkin’s Lymphoma (21 patients) and CLL (3 patients).6 Two of these EBV-reactivations occurred in CLL patients with partial responses to FC.

The data we present suggest that EBV-reactivation in CLL may not be rare, in fact the condition could be significantly under-diagnosed. All 11 cases had signs of severe CLL associated secondary immunodeficiency. The clinical presentation of EBV reactivation was as varied as in BLPD associated with primary immunodeficiencies, and can mimic the symptoms of active CLL. Therefore, EBV-reactivation must be considered in febrile CLL patients with high-risk biological risk features and/or fludarabine-refractory disease. In the absence of clinical trials for the management of EBV reactivation in CLL, the treatment strategy should include rituximab as in the non-CLL setting, possibly in combination with chemotherapy as recommended for Richter’s syndrome.7 Further research is needed to determine a threshold for differentiation between a significant and non-significant increase in EBV copies, and to determine when rituximab therapy should be initiated.

Footnotes

• Funding: JJ and CG receive research funding from Roche and Bayer-Schering.