Inclusion Criteria:

1. Have an active malignancy (defined as a diagnosis of cancer, other than basal cell or
squamous cell carcinoma of the skin).

2. Have been objectively diagnosed with thrombosis involving a deep vein (documented
using compression ultrasound with Doppler [CUD], computed tomography with/without
venography [CT/CTV], magnetic resonance imaging with/without venography [MRI/MRV],
conventional venography [CV]) or pulmonary artery (ventilation-perfusion scan [V/Q],
spiral CT angiography [SCTA], or conventional pulmonary angiogram [CPA]) within the
96 hours of enrollment, and require anticoagulation therapy.

3. Are judged clinically to require anticoagulation therapy.

4. Are in the age range of ≥ 36 weeks gestation and < 19 years.

5. Have given signed informed consent (and assent, as appropriate) to participate prior
to enrollment.

Exclusion Criteria:

1. Weight ≤ 3.0 kg or > 100 kg.

2. Platelet count ≤ 50,000/mm3 (despite appropriate medical measures to support platelet
count).

3. Received oral anticoagulant therapy within 72 hours of enrollment.

4. History of administration of therapeutic doses of LMWH or unfractionated heparin for
a treat period of > 96 hours (or > 8 doses of LMWH) for the qualifying VTE.

5. Received unfractionated heparin within 3 hours, or LMWH within 15 hours of the first
dose of dalteparin.

6. Acute VTE intervention which includes thrombolytic therapy.

7. Major bleeding at the time of screening or enrollment or an unacceptably high risk of
bleeding at the discretion of the investigator.

8. aPTT > 5 seconds above ULN, and that corrects to within normal limits upon 1:1 mixing
with normal plasma.

9. PT > 2 seconds above ULN, and that corrects to within normal limits upon 1:1 mixing
with normal plasma.

10. Calculated creatinine clearance (Schwartz method) < 60 mL/min in subjects > 1 month
of age.

11. Uncontrolled hypertension characterized by a sustained systolic pressure or diastolic
pressure > 99th percentile of age- and height-related norms.

12. History of heparin-induced thrombocytopenia (HIT).

13. Any condition in which the investigator feels the subject is unsafe or inappropriate
for study participation.

14. Insufficient subcutaneous tissue to facilitate subcutaneous drug administration.

15. Presently or previously received (within 30 days of enrollment) study drug for which
an IND/IDE is in effect, with the exception of erwinia asparaginase.

16. Pregnant or lactating female.

17. Refusal by sexually active post-menarche female subjects to adhere to an acceptable
form of contraception.

18. Unable or unwilling to comply with scheduled follow-up visits.

19. Inability to obtain written informed consent from subject or parent or legally
acceptable representative for the subject.