Phase 1 evaluation of the respiratory syncytial virus-specific monoclonal antibody palivizumab in recipients of hematopoietic stem cell transplants

Intravenous palivizumab (15 mg/kg) was investigated in 2 phase 1 studies am ong recipients of hematopoietic stem cell transplants (HSCTs). Study 1 incl uded 6 HSCT patients without active respiratory syncytial virus (RSV) infec tion. Study 2 included 15 HSCT patients with RSV upper respiratory tract in fection (URTI; n = 3) or RSV interstitial pneumonia (IP; n = 12), all of wh om also received aerosolized ribavirin. Peak serum concentrations of palivi zumab in the 2 studies were similar. The mean serum half-life was 22.4 days in study 1, which mainly included autologous HSCT recipients, and 10.7 day s in study 2, which mainly included allogeneic HSCT recipients. No antibodi es to palivizumab were detected in study 1. No adverse events were attribut ed to palivizumab in the 2 studies. In study 2, all 3 patients with RSV URT I recovered without progression to lower respiratory tract disease, and 10 (83%) of the 12 patients with RSV IP survived the 28-day study period. Thus , palivizumab appears to be safe and well tolerated in HSCT recipients.