Inclusion Criteria:
* Ability to understand and voluntarily sign an informed consent form (ICF) prior to any study related procedures.
* Age ≥ 18 years at the time of signing the ICF.
* Histologically or cytologically confirmed diagnosis of advanced solid tumors, with the following additional requirements:
Dose-escalation phase: Patients with advanced solid tumors harboring a RET gene alteration who have failed standard therapy or are intolerant to standard therapy.
Dose-expansion phase:
Cohort 1: Locally advanced or metastatic NSCLC with RET gene fusion who have progressed after at least one prior line of therapy, which must include a RET inhibitor.
Cohort 2: Treatment-naïve patients with locally advanced or metastatic NSCLC harboring a RET gene fusion.
Cohort 3: Other advanced solid tumors harboring RET gene alterations.
* At least one measurable target lesion according to RECIST version 1.1.
* Documentation of a RET fusion or other activating RET gene alteration (based on a local or central laboratory report).
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, with no deterioration within the 2 weeks prior to the first dose of study drug.
* Life expectancy of at least 3 months.
Exclusion Criteria:
* Presence of other known oncogenic driver mutations.
* Prior anti-tumor therapy within specified washout periods prior to first dose (e.g., small molecules, biologics, radiotherapy, major surgery), or failure to recover from clinically significant toxicities.
* Clinically significant uncontrolled or active conditions, including but not limited to:
Inadequate bone marrow, hepatic, or renal function. Significant cardiovascular disease (e.g., uncontrolled hypertension, prolonged QTc, poor ejection fraction, recent thromboembolic events).
Active or uncontrolled infections, bleeding diathesis, or significant pleural/abdominal/pericardial effusion requiring intervention.
Central nervous system metastases unless stable and asymptomatic off steroids.
* Conditions affecting oral drug absorption or gastrointestinal function.
* History of severe allergic reactions to similar agents.
* Pregnant or lactating women, or patients with serious concurrent medical or psychiatric conditions that would compromise safety or study compliance.
