Varicella-Zoster Virus Prophylaxis with Low-Dose Acyclovir in Patients with Multiple Myeloma Treated with Bortezomib

Background: Varicella-zoster virus (VZV) reactivation is a common complication in patients with multiple myeloma (MM) treated with bortezomib, with an incidence rate of 10%-60%. The aim of our study was to analyze the effect of acyclovir prophylaxis in this patient population. Patients and Methods: We studied 98 consecutive patients with relapsed MM treated with bortezomib. Bortezomib 1.3 mg/m(2) was given on days 1, 4, 8, and 11 of a 21-day cycle. At first, patients did not receive any VZV prophylaxis, but because of the high incidence of VZV reactivation, VZV prophylaxis with acyclovir was implemented subsequently. Results: A total of 11 patients treated with bortezomib did not have any VZV prophylaxis, and 4 of these 11 patients (36%) developed VZV reactivation in the form of herpes zoster. No VZV reactivations were observed in the 32 patients who received acyclovir 400 mg 3 times daily or the 55 patients who received acyclovir in a dose reduced to 400 mg once daily during bortezomib treatment. Conclusion: Varicella-zoster virus reactivation is a common and serious adverse effect of bortezomib treatment. Acyclovir 400 mg once daily is sufficient to protect from VZV reactivation in patients with MM treated with bortezomib.