Inclusion Criteria:

1. Gastric or gastroesophageal junction adenocarcinoma confirmed by cytology or biopsy,
with unresectable or metastatic disease which have progressed to a
cisplatin-fluoropyrimidine based scheme (excluded neoadjuvant treatment administered
with or without concomitant radiotherapy)

2. Older than 18 years at the moment of informed consent form signature

3. Age > 18 years

4. ECOG 0-2

5. Measurable disease by RECIST criteria. Lesions have to be measured by CT-scan or MRI

6. Life expectancy > 12 weeks

7. Adequate medullary reserve and hepatic and renal function, defined according to the
following parameters:

1. Hemoglobin ≥ 9g/dl

2. Neutrophils ≥ 1,5 x 10^9/L

3. Platelets ≥100 x 10^9/L

4. Total bilirubin ≤ 1,5 times the upper limit of normal (ULN)

5. ALT (GTP) and AST (GOT) ≤ 2,5 times the upper limit of normal (ULN) (≤ 5 times
the ULN in patients with hepatic metastasis)

6. PT-INR-PTT ≤ 1,5 times the ULN. (The patients under anticoagulant treatment with
dicumarin or heparin can be included if there is no previous evidence of
alteration in these parameters)

7. Creatinine clearance > 30ml/min

8. The patients have to be able to understand the meaning of their participation in the
trial and voluntary give their participation consent signing the informed consent
form

Exclusion Criteria:

1. More than one line for the treatment of locally advanced disease

2. Active ischemic cardiopathy. History of cardiac disease defined as follow:

1. Congestive cardiac failure > class 2 from the NYHA

2. Active coronary disease. The recruitment of patients with solved myocardial
infarction is allowed, if diagnosed at least 6 months before the trial start

3. Cardiac arrhythmia requiring treatment with antiarrhythmic drugs. (The treatment
with beta-adrenergic antagonists or digoxin is allowed)

4. Non-controlled arterial hypertension

3. Non-controlled intercurrent illness

4. Symptomatic sensitive peripheral neuropathy

5. Another malignant disease diagnosed in the past 5 years, except in situ cervix
carcinoma adequately treated, non-melanoma skin carcinoma, superficial bladder tumor
(Ta, Tis and T1), or any tumor treated in a curative way until 3 years prior to the
recruitment

6. Pregnant or breastfeeding women. Women will have to undergo a pregnancy test within 7
days prior to the recruitment. Both men and women recruited in the trial will have to
use appropriate barrier contraceptive methods during their sexual relations during
the trial period and at least until two weeks after its completion. Men participating
in this trial will have to continue using this contraceptive methods at least until 3
months after the treatment completion

7. Chronic diseases: AIDS, Hepatitis B and/or Hepatitis C

8. Clinically active severe infection (Grade 2 NCI-CTC version 3.0)

9. Cerebral metastasis or meningeal tumor

10. Patients requiring chronic corticosteroid treatment or high doses of corticosteroids
or any other immunosuppressive treatment

11. Patients having undergone a major surgery within the 4 weeks prior to the trial start

12. Patients having completed a chemotherapy or radiotherapy treatment within the 4 weeks
prior to the clinical trial start (except palliative radiotherapy, within the 2-weeks
prior to the clinical trial start)

13. Previous treatment using a RAS pathway inhibitor

14. Any medical or severe psychiatric condition or drug consumption involving a serious
risk for the patient if taking part in the clinical trial or that can prevent the
signature of the informed consent form

15. Patients unable to swallow medication