Panitumumab-based Maintenance in Patients With RAS Wild-type, Metastatic Colorectal Cancer (Valentino)

Inclusion Criteria:

1. Written informed consent prior to performance of any study procedure;
2. Age ≥18 years;
3. ECOG Performance Status 0-1;
4. Life expectancy of at least 12 weeks in the opinion of the Investigator;
5. Histologically or cytologically confirmed adenocarcinoma of the colon or rectum, with RAS wild-type status;
6. Metastatic unresectable colorectal cancer not previously treated with standard chemotherapy for advanced or metastatic disease;
7. Measurable or non-measurable metastatic lesion(s), as defined by RECIST version 1.1;
8. Laboratory requirements:

   * Neutrophils \>= 1.5 x 109/L, Platelets \>= 100 x 109/L, and Haemoglobin \>=10g/dL
   * Total bilirubin \<= 1.5 time the upper-normal limits (UNL) of the Institutional normal values; ASAT (SGOT) and/or ALAT (SGPT) \<= 2.5 x UNL, or \<= 5 x UNL in case of liver metastases; alkaline phosphatase \<= 2.5 x UNL, \<= 5 x UNL in case of liver metastases, \<= 10 x UNL in case of bone metastases; LDH \<1500 U/L
   * Creatinine clearance (calculated according to Cockcroft and Gault) \> 60 mL/min or serum creatinine \<=1.5 x upper limit of normal (UNL);
9. Patients must be accessible for treatment and follow up. Patients registered on this trial must be treated and followed at the participating center.
10. Archival tumor tissue is required for exploratory research at enrolment.

Exclusion Criteria:

1. Has a serious illness or medical condition(s) including, but not limited to the following:

   1. Other concurrently active malignancies excluding malignancies that are disease free for more than 5 years or carcinoma-in-situ deemed cured by adequate treatment.
   2. Known brain metastasis or leptomeningeal metastasis.
   3. Active infection (ie, body temperature ≥38°C due to infection).
   4. Ascites, pleural effusion or pericardial fluid requiring drainage in last 4 weeks.
   5. Intestinal obstruction, pulmonary fibrosis or interstitial pneumonitis, renal failure, liver failure, or cerebrovascular disorder.
   6. Uncontrolled diabetes.
   7. Myocardial infarction within the last 12 months, severe/unstable angina, symptomatic congestive heart failure New York Heart Association (NYHA) class III or IV
   8. Gastrointestinal hemorrhage.
   9. Known human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)-related illness, or hepatitis B or C.
   10. Autoimmune disorders or history of organ transplantation that require immunosuppressive therapy.
   11. Psychiatric disease that may increase the risk associated with study participation or study drug administration, or may interfere with the interpretation of study results.
2. Patients who had received adjuvant oxaliplatin-based chemotherapy and had recurrence during treatment or within 12 months from its completion are excluded. Patients who had received adjuvant fluoropyrimidine mono-therapy and had recurrence during treatment or within 6 months from its completion are excluded.
3. Disease that is deemed potentially resectable after conversion chemotherapy is excluded. In particular, patients must be deemed unresectable by a multidisciplinary team, even when foreseeing a response to treatment. In case of liver metastases, the concept of resectability must take into account both the aim of oncological radicality (R0 resection) and remanent liver function considerations.
4. Treatment with any of the following within the specified time frame prior to study drug administration:

   1. Major surgery within prior 4 weeks (the surgical incision should be fully healed prior to study drug administration).
   2. Any anticancer therapy or investigational agent within prior 4 weeks
   3. Extended field radiation within prior 4 weeks or limited field radiation within prior 2 weeks.
5. Has unresolved toxicity of greater than or equal to CTCAE Grade 2 attributed to any prior therapies (excluding anemia, alopecia, skin pigmentation). In particular, patients with platinum induced neurotoxicity greater than or equal CTCAE Grade 2 should be excluded.
6. Is a pregnant or lactating female, or is planning to become pregnant during treatment and within 2 months after the end of treatment with panitumumab. Women of child-bearing potential with either positive or no pregnancy test at baseline. Women of child-bearing potential or sexually active men not willing to use contraception during study and for at least 2 months after end of treatment with panitumumab. Postmenopausal women must have been amenorrheic for at least 12 months to be considered of non-child bearing potential.