Oral Acyclovir Is an Effective in Decreasing the Incidence of Bortezomib Associated Herpes Zoster in Patients with Multiple Myeloma.

Introduction: Bortezomib, a proteasome inhibitor is an effective antimyeloma therapy. We recently reported that multiple myeloma patients treated with bortezomib or bortezomib based regimen resulted in a higher incidence of herpes zoster (HZ). The exact etiology of this side effect remains unknown though our investigation demonstrated prolonged lymphopenia among patients treated with bortezomib. The high incidence of HZ among bortezomib treated patients prompted to prospectively investigate the role of antiviral prophylaxis in this patient population. Here we report for the first time the efficacy of acyclovir as prophylaxis for bortezomib associated HZ. Patients and Methods: We prospectively evaluated the impact of oral acyclovir (400mg PO twice daily for the duration of bortezomib therapy) on the incidence of HZ. All patients with multiple myeloma who were treated with bortezomib or bortezomib based regimens, and received prophylactic acyclovir were evaluable for this analysis. To compare the overall proportion of HZ among patients who received acyclovir prophylaxis and the historical control, Fisher exact test was used. Results: A total of 51 consecutive patients (27 M and 24 F) received acyclovir as prophylaxis. The median age was 61 (range 40–81 years), with advance stage MM noted in 86% (n=44) patients. Among these 69% had previously untreated MM while 31% had relapsed or refractory disease. Single agent bortezomib was given to 11 patients and 40 patients received bortezomib in combination with other antimyeloma agents (such as thalidomide, pegylated liposomal doxorubicin, dexamethasone, cyclophosphamide and/or lenalidomide). The overall incidence of HZ was 0% among patients receiving the acyclovir prophylaxis vs. 13% in the historical control. There was a significant difference in the overall proportion of HZ among patients who received acyclovir prophylaxis and the historical control (p = 0.0026). Conclusion: This is the first report on the efficacy of acyclovir for the prevention of bortezomib associated HZ in MM patients. While bortezomib is an effective antimyeloma therapy, an important side effect with significant morbidity is reactivation of HZ. Here we demonstrate for the first time that this side effect can be effectively prevented by oral acyclovir. Our observation warrants further evaluation. Considering significant morbidity associated with HZ we recommend the routine use of prophylactic acyclovir (or other antiviral agents) for patients being treated with bortezomib or bortezomib-based therapies.