Interventional Study of INCB 99280 With Ipilimumab in Participants With Select Solid Tumors

Inclusion Criteria:

• Prior systemic therapy, diagnoses and disease setting as follows:

• For Part 1 (dose escalation), and no history of treatment with anti-CTLA-4 oranti-PD-(L)1 therapy and one of the following,

• Unresectable or metastatic cutaneous melanoma, or

• Unresectable of metastatic Child-Pugh Class A NDD not eligible forsurgical and/or locoregional therapy, or

• Intermediate or poor-risk advanced clear cell RCC, or

• MSI-H or dMMR metastatic CRC and able to provide fresh or archival tumortissue for central confirmation of MSI-H or dMMR.

• For Part 2 (dose expansion), IO treatment -naïve, e.g., no prior receipt of ananti PD-1, anti-PD-L1 or PD-L1, anti-CTLA-4, GITR, LAG3, TIM3, OX-40, IL-2, 4-1BB or other immune modulator, and have not received prior systemic therapyand one of the following,

• Unresectable or metastatic Child-Pugh Class A HCC not eligible forsurgical and/or locoregional therapy, or

• Intermediate - or poor-risk advanced clear cell RCC.

• ECOG performance score of 0 or 1.

• Life expectancy > 3 months, in the opinion of the investigator.

• Histologically confirmed solid tumors with measurable disease per RECIST v1.1.

• Exception: HCC may be diagnoses based on cross-sectional multiphasicimagining using the AASLD criteria.

• Willingness to avoid pregnancy or fathering children.

Exclusion Criteria:

• Known history of an additional malignancy.

• Central nervous system (CNS) metastases requiring treatment and/or leptomeningealdisease.

• Toxicity from prior therapy that has not recovered.

• Received thoracic radiation within 6 months of the first dose of study treatment.

• Participation in another interventional clinical study while receiving INCB099280.

• Impaired cardiac function of clinically significant cardiac disease.

• History of evidence of interstitial lung disease including non-infectionspneumonitis.

• Presence of gastrointestinal condition that may affect drug absorption

• Any autoimmune disease requiring systemic treatment in the past 5 years.

• Diagnosis of immunodeficiency or receiving chronic systemic steroid therapy at adaily dose exceeding 10 mg of prednisone or equivalent

• Active infection requiring systemic therapy.

• History of organ transplantation, including allogeneic stem cell transplantation.

• Receipt of system antibiotics within 28 days of first dose of study treatment.

• Probiotic usage is prohibited during the screening and throughout the studytreatment period.

• Received a live vaccine within 28 days of planned start of study drug.

• Laboratory values outside the Protocol-defined ranges.

Other protocol-defined Inclusion/Exclusion Criteria may apply.