PTC596 in Patients With Advanced Solid Tumors

This is a Phase 1, open-label, first-in-human, safety and pharmacokinetic (PK) study of
PTC596 in patients with advanced cancer. A variation of the traditional 3+3 dose escalation
design will be employed.

PTC596 will be administered orally on a twice a week (biw) schedule. Each 4-week period of
drug administration will be considered one cycle. The objective of the study will be to
determine the recommended Phase 2 dose (RP2D) and to determine preliminary proof of mechanism
of action.

Collectively, data from the Good Laboratory Practice (GLP) and non-GLP studies indicate that
40 mg/kg biw is approximately the severely toxic dose in 10% of animals (STD 10). Therefore,
the starting dose in this study will be calculated as one-tenth of the human equivalent dose
(HED) of 40 mg/kg biw in rats, which is 0.65 mg/kg biw.

In this study, escalating dose levels will be evaluated to determine the RP2D. Three patients
will be enrolled at the starting dose level (0.65 mg/kg biw); if 1 of the 3 patients
experiences a dose-limiting toxicity (DLT), an additional 3 patients will be enrolled at the
same dose level. Thus, 3 to 6 patients will receive the starting dose level of 0.65 mg/kg.
Dose escalation will continue until the occurrence of DLT in ≥2/6 patients at a given dose
level. Dose escalation will occur in approximately 100% increments until Grade ≥2,
first-cycle toxicity is seen in at least 2 patients across all dose levels, after which dose
escalation will occur in smaller (50% or 33%) increments.

Inclusion Criteria:

- Patients must have histologically or cytologically confirmed solid malignancy that is
metastatic or unresectable, for which standard curative measures do not exist, that
has progressed on at least one line of standard therapy or for which no standard
therapies exists

- Discontinuation of all other therapies (including other investigational drugs,
radiotherapy, or chemotherapy) for the treatment of cancer ≥4 weeks (≥6 weeks if
nitrosoureas, ≥12 weeks if radiotherapy) before initiation of study treatment

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

- Life expectancy of at least 3 months

- A measured or estimated creatinine clearance (CrCl) ≥60 mL/min/1.73 m2

Exclusion Criteria:

- Prior bone marrow/hematopoietic stem cell transplantation

- History of solid organ, bone marrow, or progenitor cell transplantation

- History of major surgical procedure within 28 days prior to start of study treatment

- Evidence of ongoing systemic bacterial, fungal, or viral infection. Known human
immunodeficiency virus (HIV) infection or acquired-immunodeficiency syndrome
(AIDS)-related illness

- Any of the following in the past 6 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,
other arterial thromboembolic event, or pulmonary embolism