BACKGROUND The incidence of herpes zoster is substantial during bortezomib treatment in patients with multiple myeloma (MM).

OBJECTIVES This study aimed to elucidate the effect of chemotherapy with or without bortezomib in MM patients on their herpes zoster incidence and varicella zoster virus (VZV)-specific cell-mediated immunity (CMI).

STUDY DESIGN Peripheral blood mononuclear cells were collected at baseline and after 1 month of bortezomib-based or thalidomide-based chemotherapy and then analyzed using VZV-specific interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay. The clinical data from these patients were analyzed in relation to the ELISPOT results.

RESULTS Of 58 patients analyzed, 39 patients received bortezomib and the other 19 patients, thalidomide. Among them, 5 patients developed herpes zoster during chemotherapy; all 5 were being treated with the bortezomib-based regimen and were not receiving prophylactic anti-viral agents. The median onset of herpes zoster was 32 days (range, 15-95 days) from the initiation of chemotherapy. Among patients who received bortezomib therapy, acyclovir prophylaxis significantly reduced the risk for herpes zoster (100-day cumulative incidence, 0% vs. 49.5%; p<0.001). Spot-forming cell (SFC) counts in the IFN-γ ELISPOT assay decreased from baseline after bortezomib (p=0.011) or thalidomide (p=0.096) treatment. Patients with baseline SFCs greater than 20/10(6) mononuclear cells exhibited significantly higher incidence of herpes zoster (100-day cumulative incidence, 34.8% vs. 0%; p=0.040).

CONCLUSIONS Bortezomib treatment significantly reduced VZV-specific CMI, and high baseline SFC counts in patients receiving this treatment without acyclovir prophylaxis were associated with a significantly increased risk for herpes zoster.