In a phase 3 study, levofloxacin prophylaxis significantly reduced bacteremia in children with acute leukemias who received intensive chemotherapy.
However, the risk of bacteremia was not significantly reduced with levofloxacin in another cohort of children who underwent hematopoietic stem cell transplant (HSCT).
Sarah Alexander, MD, of the Hospital for Sick Children in Toronto, Ontario, Canada, and her colleagues reported these findings in JAMA.
This multicenter, randomized trial (ACCL0934) enrolled patients aged 6 months to 21 years.
There were 200 patients with acute leukemias (acute myeloid leukemia or relapsed acute lymphoblastic leukemia) who were set to receive chemotherapy and 424 patients who were to receive a myeloablative autologous or allogeneic HSCT.
The acute leukemia patients were randomized to receive no prophylaxis (n=100) or levofloxacin prophylaxis (n=100) for two consecutive cycles of chemotherapy.
The HSCT recipients were randomized to receive no prophylaxis (n=214) or levofloxacin prophylaxis (n=210) during one HSCT procedure.
In the primary analysis of the acute leukemia group (n=195), the incidence of bacteremia was 21.9% for those randomized to levofloxacin and 43.4% for those who did not receive prophylaxis (P=0.001).
In the primary analysis of the HSCT group (n=418), the incidence of bacteremia was 11.0% in the levofloxacin arm and 17.3% in the control arm (P=0.06).
However, a post hoc analysis accounting for time at risk showed a significant difference in favor of prophylaxis in both the acute leukemia and HSCT groups and a similar effect size between groups.
For the acute leukemia group, the rate of bacteremic episodes in the post hoc analysis was 4.9 versus 9.4 per 1,000 patient-days in the prophylaxis and control arms, respectively (P=0.008).
In the HSCT group, the rate of bacteremic episodes was 5.3 versus 10.0 per 1,000 patient-days in the prophylaxis and control arms, respectively (P=0.02).
The researchers said it is possible that the effect of prophylaxis was similar between the HSCT and acute leukemia groups, but there was reduced power to detect a significant difference because of fewer events among HSCT recipients.
However, the differences between the HSCT and acute leukemia groups in the primary analysis might also be explained by differences in supportive care measures or infections with pathogens that had differential sensitivity to levofloxacin.
The researchers noted that levofloxacin-resistant pathogens, such as viridans group streptococcal isolates and several gram-negative isolates, often were detected in patients who had bacteremia events despite prophylaxis. This suggests other interventions in combination with levofloxacin prophylaxis are probably needed to further decrease risk.
Dr. Alexander and her colleagues also said further randomized studies are needed to better understand the risks of levofloxacin in relation to its benefits.
In the current study, there were 23 serious adverse events reported in 8 patients. Twelve of these events, occurring in two patients, may have been related to levofloxacin.
This research was supported by grants from the Community Clinical Oncology Program and National Cancer Institute. Dr. Alexander reported no disclosures. Coauthors reported disclosures related to Bristol-Myers Squibb, Chimerix, Jazz Pharmaceuticals, and the Children’s Oncology Group.