Formation of new blood vessels (angiogenesis) is important for tumor growth in advanced cancer. It is known that tumors make a protein called vascular endothelial growth factor (VEGF). VEGF stimulates the formation of blood vessels that supply the tumor with nutrients and oxygen. PTC299 is an oral investigational new drug that has been shown to decrease production of VEGF in animal models of human cancer. In these animal models, oral PTC299 administration decreases VEGF levels in the tumor and in the bloodstream, decreases blood vessel numbers in the tumor, and significantly slows or halts tumor growth. When given in combination with the chemotherapeutic drug, docetaxel, PTC299 increases the antitumor activity over use of docetaxel alone. Safety studies in research animals indicate good tolerability at doses and drug levels that are higher than those planned for the clinical studies. Results from Phase 1a studies in healthy volunteers indicate that PTC299 achieves levels of PTC299 in the bloodstream that are known to be active in animal models of human cancer. This Phase 1b study is designed to test the hypothesis that PTC299 will be tolerable and will show evidence of anti-VEGF and antitumor activity when administered orally to participants with cancer.

The study will be conducted in 3 stages. In Stage 1 of the study, successive groups of 3 to 6 participants will receive progressively higher PTC299 dose levels; in this stage, treatment will be given in repeated 6-week cycles consisting of 4 weeks of oral PTC299 twice per day followed by a 2-week, no-drug period. In Stage 2, additional groups of 3 to 6 participants will be enrolled at tolerable dose levels to receive treatment in repeated 6-week cycles consisting of oral PTC299 administered 2 or 3 times per day continuously (that is, without the 2-week no-drug period as in Stage 1). In Stage 3, additional groups of 3 to 6 participants will be enrolled at tolerable dose levels to receive treatment in repeated 3-week cycles consisting of oral PTC299 administered 2 or 3 times per day continuously in combination with docetaxel (75 milligrams/meter squared [mg/m^2] intravenously [IV] every 3 weeks). All planned dose levels in all stages are expected to achieve circulating blood levels of PTC299 known to be active in animal models of human cancer. Treatment for each participant can continue as long as the therapy appears to be safely offering tumor control to that participant. Up to 76 evaluable participants will be accrued across the 3 stages.

Inclusion Criteria:

1. Age ≥18 years.

2. Body weight 40-100 kg.

3. Capable of swallowing oral medication.

4. The Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

5. Life expectancy >3 months.

6. Histologically or cytologically confirmed diagnosis of a solid tumor. Note: Participants with lymphomas may be enrolled. Participants with leukemia should not be included.

7. Presence of locally advanced or metastatic disease that is not amenable to surgery, radiation therapy, or chemotherapy with curative intent.

8. Cancer progression on or after standard therapy or cancer for which no standard therapy is available.

9. Discontinuation of all anticancer therapies ≥3 weeks before initiation of study treatment. Note: Prior treatment with antiangiogenic therapies (for example, bevacizumab, sunitinib, sorafenib, or investigational antiangiogenic agents) is allowed.

10. Acute toxic effects (as evaluated by CTCAE, Version 3.0) of any prior therapy resolved as shown below:

    • Neuropathy - Grade ≤2 (Stage 1 and 2)
    • Neuropathy - Grade ≤1 (Stage 3)
    • Alopecia - Grade ≤2 (all stages)
    • Fatigue - Grade ≤2 (all stages)
    • All others - Grade ≤1 (all stages)

11. Required baseline laboratory data:

    • Absolute neutrophil count ≥1,500/cubic millimeter (mm^3)
    • Platelets ≥100,000/mm^3
    • Hemoglobin ≥9.0 grams/deciliter (g/dL)
    • Serum total bilirubin <ULN; ≤1.5x ULN is acceptable if there is liver involvement secondary to tumor
    • Serum Alanine transaminase and Aspartate transaminase <ULN; ≤2.5x ULN is acceptable if there is liver involvement secondary to tumor
    • Serum alkaline phosphatase ≤2.5x ULN regardless of liver involvement with tumor
    • Serum albumin ≥3.0 g/dL
    • Serum creatinine ≤2.0 milligrams/liter (mg/L)
    • Urine protein <2+ by dipstick (or spot urinary protein: creatinine ratio <1.0 mg/dL:mg/dL, if quantitative method used)
    • Prothrombin time and Activated partial thromboplastin time ≤ULN
    • Serum beta-human chorionic gonadotropin (HCG) negative

12. Willingness, if not postmenopausal or surgically sterile, to abstain from sexual intercourse or employ an effective method of contraception during the study periods.

13. Willingness and ability to comply with scheduled visits, drug administration plan, study procedures, and study restrictions.

14. Ability to provide written informed consent.

15. Evidence of a personally signed informed consent indicating that the participant is aware of the neoplastic nature of his or her disease and has been informed of the procedures to be followed, the experimental nature of the therapy, alternatives, potential benefits, possible side effects, potential risks and discomforts, and other pertinent aspects of study participation.

16. An interval of >2 weeks from corticosteroid dose stabilization prior to obtaining the baseline MRI scan in participants with CNS malignancy.

Exclusion Criteria:

1. Unstable brain or leptomeningeal disease based on history and physical examination. Note: Enrollment of participants with central nervous system metastases is permitted if such disease is considered stable in the judgment of the investigator. A baseline magnetic resonance imaging (MRI) scan of the brain is required if there is clinical suspicion of central nervous system metastases, hemorrhage, thromboembolism, or increased intracranial pressure.
2. Any of the following in the past 3 months: myocardial infarction, unstable angina, coronary/peripheral artery bypass graft, congestive heart failure (New York Heart Association Class III or IV), cerebrovascular accident, transient ischemic attack, any other arterial thromboembolic event, or pulmonary embolism.
3. Known coagulopathy or bleeding diathesis.
4. Known history of drug-induced liver injury.
5. Resting systolic blood pressure >180 millimeters of mercury (mmHg) or diastolic blood pressure >110 mmHg.
6. Evidence of ongoing systemic bacterial, fungal, or viral infection (including upper respiratory tract infections). Note: Participants with localized fungal infections of skin or nails are eligible.
7. Pregnancy or breast-feeding.
8. Ongoing alcohol or drug addiction.
9. Prior exposure to PTC299.
10. Exposure to another investigational drug within 4 weeks prior to the study treatment.
11. Concurrent participation in another therapeutic treatment trial.
12. History of major surgical procedure within 14 days prior to enrollment in this study.
13. Psychological, social, familial, or geographical factors that would prevent regular follow up.
14. Prior or ongoing clinically significant illness, medical condition, surgical history, physical finding, ECG finding, or laboratory abnormality that, in the investigator's opinion, could affect the safety of the participant; alter the absorption, distribution, metabolism or excretion of the study drug; or impair the assessment of study results.
15. History of severe hypersensitivity reactions to docetaxel or polysorbate 80. Note: This criterion applies to Stage 3 study candidates only.
16. Presence of malignancy that is refractory to docetaxel (that is, best response with prior docetaxel was progressive disease at first assessment). Note: This criterion applies to Stage 3 study candidates only.