• Safety and tolerability [ Time Frame: 1 to 120 days post bone marrow transplant ] [ Designated as safety issue: Yes ]
  

• Incidence of bacteremia [ Time Frame: 1 to 120 days post bone marrow transplant ] [ Designated as safety issue: Yes ]
  
• Incidence and severity of graft-versus-host disease [ Time Frame: 1 to 120 days post bone marrow transplant ] [ Designated as safety issue: Yes ]
  
• Infection-related mortality [ Time Frame: 1 to 120 days post bone marrow transplant ] [ Designated as safety issue: Yes ]
  
• Overall mortality [ Time Frame: 1 to 120 days post bone marrow transplant ] [ Designated as safety issue: Yes ]
  

OBJECTIVES:

Primary

• Assess the safety and tolerability of giving prophylactic moxifloxacin hydrochloride during the post-engraftment phase in patients who have undergone allogeneic stem cell transplantation. (Pilot study)
• Compare the efficacy, in terms of reducing the incidence of clinically and microbiologically documented bacterial infections, in patients who have undergone allogeneic stem cell transplantation treated with prophylactic moxifloxacin hydrochloride vs placebo during the post-engraftment phase. (Phase III)

Secondary

• Determine the incidence of clinically and microbiologically documented bacterial infections in these patients. (Pilot study)
• Assess the impact of moxifloxacin hydrochloride on the incidence of bacteremia in these patients. (Phase III)
• Compare the percentage of time on systemic antibiotics and days hospitalized in patients treated with these regimens. (Phase III)
• Compare the incidence of veno-occlusive disease of the liver in patients treated with these regimens. (Phase III)
• Compare the incidence and severity of graft-versus-host disease in patients treated with these regimens. (Phase III)
• Compare the infection-related mortality and overall mortality of patients treated with these regimens.

OUTLINE: This is a pilot study followed by a randomized, double-blind, placebo-controlled, multicenter phase III study. Patients are stratified according to gender and race (white vs. non-white). The first 20 patients are assigned to the pilot study.

Patients assigned to the pilot study receive oral moxifloxacin hydrochloride once daily beginning after neutrophil recovery (ANC > 1,500/mm³) from allogeneic stem cell transplantation (ASCT) and continuing until day 100 post-transplantation in the absence of disease progression or unacceptable toxicity. Subsequent patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients receive oral moxifloxacin hydrochloride once daily beginning after neutrophil recovery (ANC > 1,500/mm³) from ASCT and continuing until day 100 post-transplantation.
• Arm II: Patients receive oral placebo once daily beginning after neutrophil recovery (ANC > 1,500/mm³) from ASCT and continuing until day 100 post-transplantation.

In both arms, treatment continues in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed at day 120 post-transplantation.

PROJECTED ACCRUAL: A total of 240 patients will be accrued for this study.