No evidence of JC virus reactivation in natalizumab treated multiple sclerosis patients: an 18 month follow-up study.

BACKGROUND AND AIM: Natalizumab, used as therapy for multiple sclerosis (MS), has been associated with progressive multifocal leucoencephalopathy (PML), a potentially fatal disease caused by JC virus (JCV), which is not predictable by specific markers. This study evaluated whether JCV reactivation occurred in the urine and/or plasma in 42 MS patients treated with natalizumab over 18 months, and followed by a thorough monitoring programme. METHODS: 42 patients (F/M: 24/18, mean age 34.4±8.9 years) were followed-up by: urine and plasma JCV-DNA PCR assay, immune cell subsets analysis, clinical and MRI evaluation, quality of life, fatigue and mood assessment. RESULTS: JCV data. At baseline, 11/42 (26%) patients had JCV viruria, persistent at serial controls. One patient acquired viruria at month 1 and one patient at month 12. No patient had JCV viraemia at baseline; three patients acquired viraemic (one at month 6, one at month 13 (both transiently) and one at month 12 (persistently viraemic)). The prevalence of JCV in both urine and plasma did not change significantly from baseline to months 12 and 18. No patient had clinical or MRI evidence of PML. Immunological data. Circulating B cells showed greater expansion (300% increase in absolute number) since the first infusion. NK cell count doubled with no change in percentage while T cell count increased with a reduced percentage, reflecting a clear redistribution in the lymphocyte compartment. CD4+ and CD8+ T cells increased proportionally, with no change in their percentage. Clinical data. 27 patients (64%) were disease free after 1 year. A marked improvement in quality of life was reported by 72% of patients. CONCLUSIONS: No evidence of subclinical JCV reactivation was found in our natalizumab treated MS patients up to 18 months of therapy, notwithstanding the marked increase in circulating B cells observed. Moreover, the efficacy of natalizumab, its tolerability and the positive impact on quality of life were confirmed in this study.

Low-dose fludarabine increases rituximab cytotoxicity in B-CLL cells by triggering caspases activation in vitro.

Rituximab maintenance therapy provides a significant benefit in patients with indolent B-cell non-Hodgkin lymphoma (NHL). Based on its efficacy in improving response to chemotherapy, the anti-CD20 antibody is currently under evaluation as maintenance therapy also in patients with B-CLL. We evaluated rituximab-mediated cytotoxicity in 10 B-CLL cases pretreated in vitro with non-cytotoxic concentrations of fludarabine. This combination induced a synergic cytotoxic effect in 8 out of 10 patients at a mean level of 26.15 +/- 13.9%, compared to 8.05 +/- 5.3% cytotoxicity observed with rituximab alone. Consistent with the viability assay, we found an increased caspase-3 activity together with activation of caspase-9 in B-CLL cells sensitive to sequential non-cytotoxic fludarabine and rituximab exposure. Non-cytotoxic fludarabine concentrations may sensitize B-CLL cells to rituximab-mediated cytotoxicity via caspase-3 activation.