Inclusion Criteria:

- Histologically confirmed diagnosis of locally advanced rectal cancer (stage II or
III) localised 0 - 12 cm ab ano as measured by rigid rectoscopy (i.e. lower and
middle third of the rectum)

- Staging requirements: trans-rectal endoscopic ultrasound (EUS) and magnetic resonance
imaging (MRI)

- Sufficient representative sample material for KRAS analysis

- Wild-type KRAS (determined by an accredited local laboratory, if not available by
pathology of Mannheim university)

- Informed consent of the patient

- Aged at least 18 years

- WHO Performance Status 0-2

- Life expectancy of al least 12 weeks

- Adequate haematological, hepatic, renal and metabolic function parameters:

- Leukocytes > 3000/mm³

- ANC ≥ 1500/mm³

- Platelets ≥ 100,000/mm³

- Hb > 9 g/dl

- Creatinine clearance ≥ 50 ml/min and serum creatinine ≤ 1.5 x upper limit of
normal

- Bilirubin ≤ 1.5 x upper limit of normal

- GOT-GPT ≤ 2.5 x upper limit of normal

- AP ≤ 5 x upper limit of normal

- Magnesium ≥ lower limit of normal

- Calcium ≥ lower limit of normal

Exclusion Criteria:

- Lower border of the tumor localised more than 12 cm ab ano as measured by rigid
rectoscopy

- Distant metastases (to be excluded by CT scan of the thorax and abdomen)

- cT4 tumor (as determined by MRI and/or endorectal ultrasound)

- Risk of tumor involvement of the circumferential resection margin, according to the
MRI assessment

- Sphincter sparing is the major reason for choosing the neoadjuvant treatment approach

- Prior antineoplastic therapy for rectal cancer

- Prior radiotherapy of the pelvic region

- Major surgery within the last 4 weeks prior to inclusion

- Subject pregnant or breast feeding, or planning to become pregnant within 6 months
after the end of treatment

- Subject (male or female) is not willing to use highly effective methods of
contraception (per institutional standard) during treatment and for 6 months (male or
female) after the end of treatment (adequate: oral contraceptives, intrauterine
device or barrier method in conjunction with spermicidal jelly)

- Serious concurrent diseases

- On-treatment participation in a clinical study in the period 30 days prior to
inclusion

- Clinically significant cardiovascular disease in (incl. myocardial infarction,
unstable angina, symptomatic congestive heart failure, serious uncontrolled cardiac
arrhythmia) ≤ 1 year before enrolment

- History of interstitial lung disease, e.g. pneumonitis or pulmonary fibrosis or
evidence of interstitial lung disease on baseline chest CT scan

- History of HIV infection

- Prior or concurrent malignancy (≤ 5 years prior to enrolment in study) except
non-melanoma skin cancer or cervical carcinoma FIGO stage 0-1 if the patient is
continuously disease-free

- Known allergic reactions on study medication