Lacking effect of treatment

This study aims to investigate the efficacy and safety of the combination of pemetrexed and gemcitabine in heavily pre-treated, chemotherapy resistant colorectal cancer patients with KRAS mutations.

Inclusion Criteria:

• Histologically verified adenocarcinoma in colon or rectum
• Age >18
• Metastatic colorectal cancer progressed after chemotherapy regimens containing fluoropyrimidines, oxaliplatin and irinotecan.
• KRAS mutation in primary tumour or metastasis.
• Measurable disease according to RECIST
• ECOG performance status 0, 1 or 2
• Adequate function of liver, kidneys and bone marrow measured by biochemistry (max. 2 weeks before enrolment)
• EDTA clearance: Uncorrected GFR > 45 ml/min.
• Neutrophilocytes ≥1.5 x 10^9/l, leukocytes ≥3.0 x 10^9/l, thrombocytes ≥100x10^9/l
• ALAT ≤ 3 x upper normal value (ULN), bilirubin ≤ 3 x upper normal value, Aptt and INR normal (or 2-3 at AC treatment). (ALAT and basic phosphatase ≤ 5 x upper normal value in case of liver metastases).
• Blood samples and paraffin embedded tissue from primary tumour and/or metastases for translational research.
• Fertile men and women (women <2 year after last menstruation) must use efficient birth control.
• Signed informed consent.

Exclusion Criteria:

• Clinically significant other concurrent disease making the patient unfit for participation in the study according to the investigator.
• Other malignant disease within 5 years prior to study enrolment, except from planocellular and basal cell carcinomas in the skin or carcinoma-in-situ cervix.
• Other experimental treatment within 30 days prior to treatment start.
• Pregnant or breastfeeding women.
• Clinical or radiological signs of CNS metastases.
• Planned radiation of target lesions.
• Concurrent vaccination against yellow fever.