Received chemotherapy, radiotherapy, biologics, endocrine therapy, immunotherapy, or other antitumor treatments within 4 weeks or 5 half-lives (whichever is shorter) before the first dose of the study drug, including: nitrosoureas or mitomycin C within 6 weeks prior; oral fluoropyrimidines or small-molecule targeted agents within 2 weeks or 5 half-lives (whichever is shorter); Chinese herbal medicines with antitumor indications within 2 weeks prior.

Received any non-marketed investigational drugs or therapies within 4 weeks prior to the first dose.

Undergone major organ surgery (excluding needle biopsy or surgery for pathologic fractures), significant trauma, or planned elective surgery during the trial within 4 weeks prior.

Used CYP3A4-sensitive substrates, strong inhibitors/inducers, CYP2C8-sensitive substrates, or P-gp inhibitors (see Appendix 3) within 14 days or 5 half-lives (whichever is shorter) prior.

Previously treated with PRMT5 or MAT2A inhibitors.

QTc interval ≥480 ms (mean of 3 measurements) on screening/baseline 12-lead ECG.

Prior allogeneic hematopoietic stem cell/bone marrow transplantation or solid organ transplantation, or current use of immunosuppressants/anti-rejection drugs.

Known allergy to any active/inactive ingredient of the study drug.

Adverse reactions from prior antitumor therapy not resolved to CTCAE v5.0 Grade ≤1 (except non-risks like alopecia, Grade 2 peripheral neuropathy, or stable hypothyroidism on hormone replacement).

Hepatitis B (HBsAg+ with HBV-DNA ≥2500 copies/mL or 500 IU/mL), HCV (HCV-RNA > lower limit of detection), HIV-positive, or syphilis (both specific/non-specific antibodies positive).

Symptomatic/active CNS metastases, leptomeningeal disease, or spinal cord compression. Asymptomatic CNS metastases may enroll if:

1. Measurable extracranial lesions per RECIST v1.1;
2. No new/progressive CNS lesions for ≥4 weeks with stable neurologic symptoms;
3. No seizures/increased intracranial pressure;
4. No steroids/antiepileptics/dehydrants for ≥2 weeks.

Clinically significant third-space fluid accumulation (e.g., massive ascites/pleural effusion).

Cardiovascular Disease: severe arrhythmias (e.g., ventricular arrhythmias requiring intervention, AV block II-III); ACS, CHF, aortic dissection, stroke, or Grade ≥3 cardiovascular events within 6 months; NYHA Class ≥II or high-risk structural heart disease; uncontrolled hypertension (SBP ≥150 mmHg and/or DBP ≥95 mmHg); QTc prolongation risks (e.g., heart failure, uncorrected hypokalemia, congenital/family history of long QT syndrome, concomitant QT-prolonging drugs).

Systemic treatment for active infection within 4 weeks prior.

Acute esophageal/GI diseases affecting drug absorption (e.g., bowel obstruction, Crohn's disease, ulcerative colitis, short bowel syndrome).

Pulmonary Disease: interstitial lung disease (ILD), pulmonary fibrosis, or drug-induced pneumonitis requiring treatment.

Other Severe Conditions: hepatic, renal, neurologic/psychiatric, endocrine, hematologic, or immune disorders compromising study participation.

Other malignancies within 5 years (except cured malignancies like basal/ squamous cell skin cancer, low-risk prostate cancer, papillary thyroid cancer, or excised in situ cancers).

Known alcohol/drug dependence.

Psychiatric disorders or poor adherence.

Pregnant or breastfeeding women.

Investigator's Discretion: any other clinical/laboratory abnormalities deemed unsuitable for the study.