The purpose of this study is to evaluate the cardiac safety of TAS-102 in patients with advanced solid tumors.

This is a Phase 1, nonrandomized study to evaluate the cardiac safety of TAS-102 in patients with advanced solid tumors. The study is conducted in 2 phases: the cardiac safety evaluation phase to investigate cardiac repolarization and the cardiac safety profile (Cycle 1) and the extension phase to assess the safety profile and antitumor activity (subsequent cycles).

Inclusion Criteria:

1. Has provided written informed consent
2. Has advanced solid tumors (excluding breast cancer) for which no standard therapy exists
3. Has received no more than 5 prior cancer therapies
4. ECOG performance status of 0 or 1
5. Is able to take medications orally
6. Corrected QT interval using Bazett's correction is no more than 450 msec on resting ECG
7. Has adequate organ function (bone marrow, kidney and liver)
8. Women of childbearing potential must have a negative pregnancy test and must agree to adequate birth control if conception is possible. Males must agree to adequate birth control.

Exclusion Criteria:

1. Has had certain other recent treatment e.g. major surgery, extended field radiation, anticancer therapy, received investigational agent, within the specified time frames prior to study drug administration
2. Certain serious illnesses or medical condition(s)
3. Has a family history of unexplained sudden death or long QT syndrome
4. Has had a documented cardiovascular complication following a fluoropyrimidine-derived treatment
5. Is a patient for whom it is not technically possible to obtain quality ECG tracings
6. Is receiving a concomitant drug that is known to affect QT interval or to be arrhythmogenic
7. Has unresolved toxicity of greater than or equal to CTCAE Grade 2 attributed to any prior therapies
8. Known sensitivity to TAS-102 or its components
9. Is a pregnant or lactating female
10. Refuses to use an adequate means of contraception (including male patients)