Purpose: Antiviral prophylaxis is commonly prescribed to haematological cancer patients. We conducted a systematic review and meta-analysis to quantify its overall benefit in specific clinical scenarios.
Methods: Randomised controlled trials assessing antiviral prophylaxis versus placebo, no treatment, pre-emptive treatment or another antiviral drug were included. Patients undergoing haematopoietic stem cell transplantation (HSCT) or intensive chemotherapy for acute leukaemia or high-grade lymphoma were included. No restrictions on language, year or publication status were applied. Overall mortality, herpes simplex virus (HSV) and cytomegalovirus (CMV) diseases were assessed as primary outcomes. Pooled relative risks (RRs) and numbers needed to treat (NNT) with 95% confidence intervals (CI) are reported.
Results: HSCT was the condition assessed in 22 trials and intensive chemotherapy in 5 trials. In the pre-engraftment setting of autologous or allogeneic HSCT, antiviral prophylaxis (mainly acyclovir for HSV seropositive recipients) significantly reduced HSV (NNT 2, 2-2, control event rate (CER) 61.9%) and CMV disease, with no effect on overall mortality. In the allogeneic post-engraftment setting (mainly CMV-seropositive recipients/donors), antiviral prophylaxis resulted in a significant reduction in overall mortality, RR 0.79 (0.65-0.95), NNT 12 (7-50, CER 39.4%) and all viral-related outcomes. In this setting, acyclovir significantly reduced overall mortality (RR 0.71, 0.53-0.96, 4 trials) and ganciclovir/maribavir significantly reduced CMV disease (RR 0.26, 0.14-0.48, 5 trials). During chemotherapy, acyclovir significantly decreased HSV disease (NNT 3, 2-4, CER 37.4%) and infection rates, with no effect on mortality.
Conclusions: Antiviral prophylaxis reduced mortality with a small NNT in the post-engraftment setting of allogeneic HSCT. In the pre-engraftment phase and during chemotherapy only viral-related morbidity was reduced.