Background

To evaluate the safety and effectiveness of plerixafor for stem cell mobilization prior to autologous transplant in Japanese children aged <15 years.

Methods

A multicenter post-marketing surveillance study was conducted in Japan to evaluate the safety and effectiveness of plerixafor in routine clinical practice. This subgroup analysis examined the safety and effectiveness of plerixafor administered as a once-daily subcutaneous injection in children aged <15 years. The primary effectiveness outcome was the proportion of patients with 2 × 106 cells CD34+ cells/kg collected via apheresis within 4 days.

Results

Eighteen patients with solid tumors were included in this analysis. Their median age was 6.0 years (range: 1─13 years). In addition to granulocyte colony-stimulating factor, all patients had received chemotherapy immediately prior to plerixafor administration. The mean ± standard deviation daily dose of plerixafor was 0.24 ± 0.01 mg/kg. Seven of the 18 patients (38.9%) developed adverse drug reactions (ADRs), all occurring in patients aged ≥6 years and weighing ≥16 kg. The most common ADRs were pyrexia (n=4), vomiting (n=3), nausea (n=2), and abdominal pain (n=2). Serious ADRs occurred in 2/18 patients (11.1%), but these resolved without sequelae. Twelve of the 18 patients (66.7%) achieved a CD34+ cell count ≥2 × 106 cells/kg within 4 days after the start of plerixafor administration.

Conclusions

The results provide an encouraging signal that plerixafor 0.24 mg/kg may be safe and effective in pediatric patients in routine clinical practice in Japan, but further research in larger studies is needed.