A Phase I/II, Open-label Study to Investigate the Safety, Tolerability, PK, and Preliminary Efficacy of FB849

Inclusion Criteria: * Subject should understand, sign, and date the written ICF prior to screening. * Male or female aged 18 years or older. * Subjects must have at least 1 measurable target lesion according to RECIST version 1.1. * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 * Life expectancy ≥ 3 months in the opinion of the investigator. * Adequate organ function and bone marrow function as indicated by the following screening assessments performed within 14 days prior to the first dose of study treatment Exclusion Criteria: * Known allergy or hypersensitivity to any component of the study treatment. * Has a known additional malignancy that is progressing or has required active treatment. * Has abnormal or inadequately controlled endocrine function. * Inability to take oral medication or significant nausea and vomiting, malabsorption, external biliary shunt, or significant bowel resection that would preclude adequate absorption of oral medication. * Previous anti-cancer therapy, including chemotherapy (chemotherapy with nitrosourea or mitomycin should be at least 6 weeks prior to initiation of study treatment), radiotherapy, molecular targeted therapy, or other investigational drugs received ≤ 4 weeks; endocrine therapy ≤ 2 weeks or ≤ 5-half-lives (whichever is shorter) prior to initiation of study treatment.