The primary objective of this study is to find the optimal dose of balugrastim by characterizing its pharmacokinetics (PK), and by comparing the pharmacodynamics (PD) of balugrastim to filgrastim in children receiving chemotherapy.

Inclusion Criteria:

1. Histological or cytologically-confirmed solid tumor in a patient for whom the study chemotherapy regimen [Vincristine plus ifosfamide plus doxorubicin plus etoposide (VIDE), Vincristine plus doxorubicin plus cyclophosphamide alternating with ifosfamide plus etoposide (VDC/IE), Ifosfamide plus vincristine plus actinomycin D (IVA) or Ifosfamide plus vincristine plus Adriamycin (IVAd)] is considered an appropriate treatment.
2. Minimum body weight of 15 kg
3. Life expectancy of at least 3 months with appropriate therapy
4. Female or male children and adolescents aged 2 to 17 years
5. Written informed consent provided by parent(s)/legal representative(s) of the pediatric patient and patient's assent if appropriate at the time of screening.
6. Fertile patients (male or female) must use highly reliable contraceptive measures.
7. Female patients who have attained menarche must have a negative urine pregnancy test at the screening visit.
8. White blood cell (WBC) count >2.5*10^9/L, ANC ≥1.5*10^9/L, and platelet count ≥100*10^9/L (at screening and prior to chemotherapy)

Exclusion Criteria:

1. Primary myeloid disorders
2. Prior radiation therapy within 4 weeks of randomization into this study.
3. Previous exposure to filgrastim, pegfilgrastim, lenograstim or other G-CSF less than 6 months before randomization.
4. Known hypersensitivity to filgrastim, pegfilgrastim, lenograstim or any balugrastim excipients
5. Pregnancy or breastfeeding (if a patient becomes pregnant during the study she will be withdrawn from the study).
6. Major surgery, serious infection, within 3 weeks before first administration of study drug, serious trauma or compound medical procedure within the 4 weeks prior to the first study drug dose.
7. Subjects with a clinically significant or unstable medical or surgical condition that would preclude safe and complete study participation, as determined by medical history, physical exams, ECG, laboratory tests or imaging.