• Histological or cytological proof of CRC with at least confirmed peritoneal metastases (presence of additional extraperitoneal metastases is allowed);

• Disease progression or relapse upon treatment for advanced CRC with fluoropyrimidine containing chemotherapy as single agent or in combination with other anti-cancer drugs, with no treatment options at time of inclusion (combinations with oxaliplatin, irinotecan, bevacizumab and cetuximab/panitumumab are allowed);

• Age ≥ 18 years;

• Able and willing to give written informed consent and informed consent form must have been signed before start of the trial;

• WHO performance status of ≤1;

• Able and willing to undergo blood sampling for PK analysis;

• Able and willing to undergo tumor biopsy before start, during treatment and at the end of treatment;

• Life expectancy \> 3 months allowing adequate follow up of toxicity and anti-tumor activity;

• Evaluable disease according to RECIST 1.1 criteria (measurable disease for the phase II part; evaluable disease is sufficient for the phase I part);

⁃ Minimal acceptable safety laboratory values

∙ ANC of ≥1.5 x 109/L

‣ Platelet count of ≥100 x 109/L

‣ Hepatic function as defined by serum bilirubin ≤ 1.5 x ULN, ALAT and ASAT ≤ 3.0 x ULN, or ALAT and ASAT \< 5 x ULN in patients with liver metastases

‣ Renal function as defined by serum creatinine ≤ 1.5 x ULN

‣ Creatinine clearance ≥ 50 ml/min (by Cockcroft-Gault formula or MDRD);

⁃ Negative pregnancy test (urine or serum) for female patients with childbearing potential.

⁃ Able and willing to swallow tablets.