Low-dose Acyclovir is Effective for Prevention of Herpes Zoster in Myeloma Patients Treated with Bortezomib: A Report from the Korean Multiple Myeloma Working Party (KMMWP) Retrospective Study

Objective: Acyclovir prophylaxis has been considered as mandatory for patients receiving bortezomib because herpes zoster is a common adverse event associated with the use of bortezomib. Although the minimal effective dose of acyclovir for prophylaxis has not yet established, the efficacy of low-dose acyclovir prophylaxis, 400 mg once daily, has been suggested. Methods: We retrospectively reviewed the patients receiving the low-dose acyclovir which was defined as the once daily administration of acyclovir 400 or 200 mg. All patients received bortezomib-containing chemotherapy in the setting of relapsed or refractory myeloma. Results: Eighty patients received bortezomib-containing treatment as a salvage therapy. All patients received at least one or more treatments prior to bortezomib treatment, including autologous stem cell transplantation. Sixty-one patients received 400 mg of acyclovir once daily while 19 patients received 200 mg. Although seven cases of herpes zoster were observed from 80 patients (7/80, 8.75%), two cases of herpes zoster received 400 mg during the limited period from the first to the fourth cycle, and the other five received 200 mg. Therefore, there was no herpes zoster in patients who received 400 mg of acyclovir till the last cycle of bortezomib treatment. There were no adverse events associated with the use of acyclovir prophylaxis. Conclusions: The administration of acyclovir 400 mg once daily during the bortezomib treatment is an effective prophylaxis for herpes zoster in patients receiving bortezomib irrespective of disease state and the type of chemotherapy regimen.