Inclusion Criteria:

1. Patients with wild-type KRAS status of metastatic colorectal cancer treatment with
panitumumab according to label

2. treatment with pre-emptive study medication shall begin the day before treatment
start with panitumumab

3. Willingness to cope with biweekly quality of life questionnaires

4. Written Informed consent

5. Aged at least 18 years

6. ECOG Performance Status 0-2

7. Life expectancy of at least 12 weeks

8. Adequate haematological, hepatic, renal and metabolic function parameters:

- Leukocytes > 3000/mm³

- ANC ≥ 1500/mm³

- Platelets ≥ 100,000/mm³

- Haemoglobin > 9 g/dl

- Serum creatinine ≤ 1.5 x ULN

- Bilirubin ≤ 1.5 x ULN

- GOT-GPT ≤ 2.5 x ULN (in case of liver metastases GOT / GPT ≤ 5 x ULN)

- AP ≤ 5 x ULN

- Magnesium, Calcium and potassium within normal ranges (may be substituted before
study entry)

Exclusion criteria:

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

2. 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).

3. Serious concurrent diseases

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

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

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

7. History of HIV infection.

8. Other previous 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

9. Known allergic reactions on panitumumab, doxycycline or erythromycin

10. Previous treatment with anti-cancer agents directed against EGFR (e.g. cetuximab,
panitumumab, erlotinib, gefitinib, lapatinib)

11. Skin rash existing before or due to other reasons than panitumumab treatment

12. Other dermatologic disease that may interfere with correct grading of panitumumab
induced skin rash

13. Parallel treatment with anti-tumor agents other than panitumumab