Enoxaparin Thromboprophylaxis in Cancer Patients With Elevated Tissue Factor Bearing Microparticles

Inclusion Criteria:

* Histologically confirmed malignancy that is metastatic or unresectable and for which standard curative therapies do not exist. Eligible malignancies include:

  * Adenocarcinoma of the pancreas (locally advanced or metastatic)
  * Colorectal (stage IV)
  * Non-small cell lung (unresectable stage III or IV)
  * Relapsed ovarian or stage IV
  * Surgically unresectable or metastatic gastric adenocarcinoma
* First or second line therapy (within 4 weeks of initiating therapy).
* Minimum age 18 years
* Life expectancy of greater than 6 months
* ECOG Performance Status 0, 1, or 2 (Karnofsky 60% or greater).
* Participants must have normal organ and marrow function as outlined in the protocol.

Exclusion Criteria:

* Participants may not be receiving any other study agents.
* Known brain metastases should be excluded from this clinical trial because of their poor prognosis and higher potential for intracranial hemorrhage.
* Prior history of documented venous thromboembolic event or pulmonary embolism within the last 5 years years (excluding central line associated events whereby patients completed anticoagulation \> 3 months previously)
* Active bleeding or high risk for bleeding (e.g. known acute gastrointestinal ulcer)
* Any history of significant hemorrhage (requiring hospitalization or transfusion) outside of a surgical setting within the last 5 years
* History of allergic reactions attributed to compounds of similar chemical or biologic composition to enoxaparin or heparin.
* History of heparin-induced thrombocytopenia
* Presence of coagulopathy (PT or PTT\> 1.5 x upper limit of normal)
* Familial bleeding diathesis
* Known diagnosis of disseminated intravascular coagulation
* Currently receiving anticoagulant therapy
* Current use of aspirin (\>81mg daily), Clopidogrel (Plavix), cilostazol (Pletal), aspirin-dipyridamole (Aggrenox), or regular use of non-steroidal anti-inflammatory agents more than twice weekly. Maximum dose of ibuprofen is 400mg no more than twice per week.
* Uncontrolled intercurrent illness including, but not limited to, ongoing active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.