Strategic Business Decision

The purpose of this study is to evaluate the safety and preliminary antitumor activity of INCB059872 in participants with Ewing sarcoma who are refractory or relapsed from prior standard therapy and not eligible for further standard systemic therapy.

Inclusion Criteria:

• Histologically or cytologically confirmed diagnosis of Ewing sarcoma and have progressed on or after standard therapies.
• Must not be a candidate for potentially curative therapy or standard-of-care approved therapy.
• Measurable disease by computed tomography or magnetic resonance imaging based on RECIST 1.1 as determined by site radiology.
• Eastern Cooperative Oncology Group performance status 0 to 2.
• Willingness to avoid pregnancy or fathering children.

Exclusion Criteria:

• Receipt of anticancer medications, anticancer therapies, or investigational drugs within protocol-defined intervals before the first administration of study drug.
• Must have recovered (≤ Grade 2 or at pretreatment baseline) from adverse events (AEs) from previously administered therapies except for stable chronic toxicities (≤ Grade 2) not expected to resolve.
• Untreated brain or central nervous system (CNS) metastases or brain/CNS metastases that have progressed.
• Prior radiotherapy within 2 weeks of study treatment. A 1-week washout period is permitted for palliative radiation to non-CNS disease with medical monitor approval.
• Laboratory values outside the protocol-defined range at screening.
• History or evidence of bleeding disorder or active clinically significant bleeding requiring medical intervention.