The purpose of this trial is to determine the safety of hMN14 at different dose levels in the treatment of either colorectal or breast cancer.

Disease Characteristics:

• Histologic or cytologic diagnosis or either, colonic, rectal, or breast carcinoma
• Measurable lesion diagnosed by CT scan
• Recurrent/metastatic disease considered surgically unresectable.

Prior/Concurrent Therapy:

• Chemotherapy: Patients who either have failed at least one regimen of standard systemic therapy, or are clinically asymptomatic and are not presently being considered for chemotherapy (Enrollment must occur at least 4 weeks beyond last treatment)
• Other: Prior treatment with investigational agents is excluded unless follow-up is completed and patient is off study

Patient Characteristics/Inclusion Criteria:

• Performance Status: Patients with a Karnofsky performance status > 70% (or equivalent, ECOG 0-1) and expected survival of at least 3 months.
• Hematopoietic: WBC >/= 3000 mm3, neutrophils >/= 1500 mm3, platelets >/= 75,000, CEA < 300 ng/mL
• Hepatic: Serum bilirubin </= 2.0 mg/dL, ALT < 2.5 x IULN
• Cardiovascular: Patients with LVEF >/= 40% by required MUGA/2D-ECHO study.
• Pulmonary: Patients with FEV1 >/= 60% by required Pulmonary Function Tests
• Other: Patients agreeing to use a medically effective method of contraception during and for a period of 3 months after the treatment period. A pregnancy test will be preformed on each premenopausal female of childbearing potential immediately prior to entry into the study. Patients able to understand and give written informed consent. Patients with a significant concurrent medical condition that could affect the patient's ability to tolerate or complete the study.