Inclusion Criteria:

1. Acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML) requiring HSCT

2. Age ≥ 1 and ≤ 16 years at screening

3. Lansky performance status > 60%

4. Candidate for allogeneic HSCT protocol:

- Adequate kidney function: Serum creatinine: ≤ 1.5 mg/dL or creatinine clearance
or radioisotope glomerular filtration rate (GFR) ≥ 60 mL/min/1.73m2

- Adequate liver function: Serum total bilirubin: ≤ 2.0 mg/dl; aspartate
transaminase (AST)/alanine aminotransferase (ALT) ≤ 4.0 x institutional upper
limits of normal (IULN); Albumin ≥ 2 g/dL

- Adequate cardiac function: shortening fraction > 29% documented by
echocardiogram, or ejection fraction ≥ 50% documented by multigated acquisition
scan (MUGA).

- Adequate pulmonary function documented by corrected lung diffusion capacity test
(DLCO) > 50% or oxygen saturation of ≥ 92% on room air if unable to perform
pulmonary function tests

- Negative for human immunodeficiency virus (HIV), hepatitis C virus (HCV), human
T cell lymphotropic virus (HTLV)

5. Identification of an HLA-compatible donor per institutional standards

6. Assent from a minor (if the child is capable of giving assent) per Department of
Health and Human Services (DHHS) guidelines listed in 21CFR 50.55 and local
Institutional Review Board (IRB) standards.

7. Serum amylase and lipase: ≤ 1.2 x IULN

8. Negative serum/urine pregnancy test for females with childbearing potential within 4
days before administration of the first palifermin dose

9. Agreement by males and females of reproductive potential to use an effective means of
contraception 30 days prior to enrollment through Day +30 (end of treatment)

Exclusion Criteria:

1. Prior treatment with palifermin or other keratinocyte growth factors

2. Received an investigational product or device, with the exception investigational
stem cell separators, in another clinical trial within 30 days before enrollment.

3. Known to have a life threatening infection not responding well to treatment

4. Past history of veno-occlusive disease of the liver

5. Known sensitivity to any Escherichia coli-derived products with grade 3 to 4
allergies to L-asparaginase [grade 1 to 2 allergies to L-asparaginase will be
allowed].

6. Receiving glutamine or any other medication to reduce the incidence of oral mucositis
(OM) within 30 days before enrollment

7. Previous or concurrent malignancy other than entry diagnostic criteria and/or solid
organ transplantation and/or treatment of congenital immunodeficiency

8. History of pancreatitis

9. Breastfeeding (giving)