The purpose of this study is to determine the maximum tolerated dose of KBP-5209 as a single agent when given orally to adult patients with advanced solid tumors that have progressed despite standard therapy, or where there is no standard therapy.

This is a Phase 1, open-label, multicenter study of KBP-5209 administered orally once daily (QD) in 28-day treatment cycles to adult patients with advanced solid tumors which have progressed despite standard therapy or for which no standard therapy exists. This study is designed to determine the MTD or RP2D and to characterize the safety, tolerability, and PK profile of KBP-5209.

Inclusion Criteria:

• Age 18 years or older;
• Patients with histologically or cytologically confirmed, advanced solid tumors which have progressed despite standard therapy or for whom no standard therapy exists.
• Patients must have at least one measurable or non-measurable lesion (dose escalation only) as defined by RECIST v1.1
• Eastern Cooperative Oncology Group performance score 0 to 2;

Exclusion Criteria:

• Patients with symptomatic CNS metastases;
• Patients who have a known history of hepatitis C or chronic active hepatitis B or a known diagnosis of HIV
• Any significant ophthalmologic abnormality
• Patients who have any severe and/or uncontrolled medical conditions
• Significant gastrointestinal abnormalities,
• Patients who have impaired cardiac function or clinically significant cardiac diseases,
• Chemotherapy, biologic therapy, immunotherapy, radiotherapy or investigational agents within 5 half-lives or within 4 weeks (whichever is longer) prior to administration of the first dose of study drug on Day 1 or have not recovered from the side effects of such therapy;
• Treatment with third generation EGFR inhibitors
• Major surgery/surgical therapy for any cause within 4 weeks of Screening;