Inclusion Criteria:

1. Patients with histologically or cytologically confirmed metastatic CRC who have failed a first-line chemotherapeutic regimen containing oxaliplatin and 5-fluorouracil (5-FU) with or without bevacizumab, with or without other Investigational Medicinal Products (IMPs)
2. Measurable disease according to Response Criteria In Solid Tumours (RECIST)
3. Performance Status 0 - 2 according to ECOG (Eastern Cooperative Oncology Group) Performance Status
4. Age 18 years or more
5. Life expectancy > 3 months
6. Signed informed consent (IC)
7. Women of child-bearing potential (i.e., women who are pre-menopausal or not surgically sterile) must have a negative serum or urine pregnancy test within 2 weeks prior to CP-4055 treatment. Nursing patients are excluded.
8. Male and female patients must use acceptable contraceptive methods for the duration of time on study, and males also for 3 months after the last CP-4055 dose
9. Adequate haematological and biological functions

Exclusion Criteria:

1. Known brain metastases
2. Radiotherapy to more than 30 % of bone marrow
3. Participation in another therapeutic clinical study within 30 days of enrolment or during this clinical study

4. Concomitant treatment with a non-permitted medication:

   • Alternative drugs
   • High doses of vitamins
5. History of allergic reactions to ara-C or egg
6. Any serious concomitant systemic disorders incompatible with the clinical study (e.g. uncontrolled inter-current illness including ongoing or active infection)
7. Any significant central nervous system or psychiatric disorder(s) that would hamper the patient's compliance
8. Pregnancy, breastfeeding or absence of adequate contraception for both male and female fertile patients
9. Known positive status for HIV and/or hepatitis B or C
10. Drug and/or alcohol abuse
11. Any reason why, in the investigator's opinion, the patient should not participate