• Plasma pharmacokinetics of daily oral administration of XL765 in two treatment schedules [ Time Frame: Assessed at periodic visits ] [ Designated as safety issue: No ]
• Pharmacodynamic effects of XL765 on tumor tissue when administered at the MTD in two treatment schedules [ Time Frame: Assessed during periodic vixits after MTD is determined ] [ Designated as safety issue: No ]

• Plasma pharmacokinetics of daily oral administration of XL765 in subjects with solid tumors
• Pharmacodynamic effects of XL765 on tumor tissue when administered at the maximum tolerated dose

The purpose of this study is to determine the safety and tolerability of XL765. XL765 is a new chemical entity that inhibits the kinases PI3K and mTOR. In preclinical studies, inactivation of PI3K has been shown to inhibit growth and induce apoptosis (programmed cell death) in tumor cells, whereas inactivation of mTOR has been shown to inhibit the growth of tumor cells.

• Experimental: Twice daily (bid) dosing
• Experimental: Once daily (qd) dosing

Inclusion Criteria:

• Histologically confirmed advanced solid tumor that is not responding to standard therapies
• ECOG performance status of 0 - 2.
• Adequate organ and bone marrow function as defined by hematological and serum chemistry limits
• At least 18 years old.
• Both men and women must practice adequate contraception
• Informed consent

Exclusion Criteria:

• Restriction of some therapies/medications within specific timeframes prior to enrollment and during the study including chemotherapy, radiotherapy, cytokines, hormones, nitrosoureas or mitomycin C, and small-molecule kinase inhibitors
• Not recovered from the toxic effects of prior therapy
• Diagnosis of diabetes
• Pregnant or breast feeding
• Uncontrolled intercurrent illness
• Congestive heart failure, unstable angina, or a myocardial infarction within 3 months of entering the study.
• HIV positive
• Diagnosis of another malignancy may exclude subject from study