Pemigatinib and Immune Checkpoint Inhibitor Treated FGFR1/2/3 Alteration Advanced Solid Tumor

Inclusion Criteria: * Age ≥ 18 years; * Histologically or cytologically confirmed unresectable advanced solid tumors with failure or intolerance to standard treatments; * At least one measurable lesion per RECIST v1.1 criteria; * Gene testing confirms FGFR1/2/3 variants, including but not limited to mutations, fusions/rearrangements in solid tumors; * Patients have not previously used specific small molecule multi-target inhibitors of the FGFR pathway, as assessed by investigators, and have been treated with immune checkpoint inhibitors; * ECOG performance status of 0-1; * Expected survival time \> 3 months; * Laboratory criteria: 1. Absolute neutrophil count (ANC) ≥ 1.5 x 10⁹/L in the past 14 days without granulocyte colony-stimulating factor; 2. Platelets ≥ 100 x 10⁹/L without transfusion in the past 14 days; 3. Hemoglobin \> 9 g/dL in the last 14 days without transfusion or erythropoietin; 4. Total bilirubin ≤ 1.5 x upper limit of normal (ULN), or total bilirubin \> ULN but direct bilirubin ≤ ULN; 5. AST, ALT ≤ 2.5 x ULN (≤ 5 x ULN in patients with liver metastasis); 6. Serum creatinine ≤ 1.5 x ULN and creatinine clearance (Cockcroft-Gault) ≥ 50 ml/min; 7. Good coagulation function, defined as INR or PT ≤ 1.5 x ULN. If on anticoagulant therapy, PT should be within the therapeutic range of anticoagulants; * Female subjects of reproductive age must have a negative urine or serum pregnancy test within 3 days prior to the first dose (Cycle 1, Day 1). If the urine test is inconclusive, a blood test is required. Non-reproductive females are defined as post-menopausal for at least one year or surgically sterile; * Subjects with reproductive potential must use contraception with an annual failure rate of less than 1% during treatment and for 120 days after the last study drug dose (or 180 days after the last chemotherapy dose). Exclusion Criteria: * Diagnosis of other malignancies within 3 years before the first dose, except for certain treated skin carcinomas and in-situ carcinomas; * Previous treatment with selective FGFR inhibitors; * Receipt of other investigational drugs within 21 days or antitumor drugs within 14 days before the first dose; * Unresolved toxicity from prior treatments unless ≤ Grade 1 or related to alopecia or fatigue; * Known symptomatic CNS metastasis or carcinomatous meningitis. Stable patients post-treatment with no evidence of progression may be eligible if steroid-free for at least 14 days; * History of allogeneic organ or hematopoietic stem cell transplantation; * Abnormal laboratory parameters: 1. Serum phosphate \> 1.5 x ULN; 2. Elevated serum calcium or albumin-adjusted calcium outside the reference range; * Known HIV infection or positive HIV test; * Active or poorly controlled serious infection; * Need for drainage treatment for pleural effusion, ascites, or pericardial effusion; * Active hepatitis B or C infection with high viral load, or positive HBsAg or anti-HCV antibodies. Patients on antiviral therapy must meet lower thresholds; * Significant uncontrolled heart disease, including recent MI, severe heart failure, or uncontrolled arrhythmias; * Clinically significant ECG changes or history of significant cardiac issues; Screening QTcF interval \> 480 ms, or JTc interval if applicable, must be ≤ 340 ms; * Uncontrolled hypertension despite treatment; * Hepatic encephalopathy, hepatorenal syndrome, or Child-Pugh grade B or higher cirrhosis; * Major surgery within 4 weeks before the first dose or planned major surgery during the study; * Unresolved complications from prior surgery; * Pregnant or breastfeeding women, or those planning to become pregnant during the study period and for safety follow-up; * Radiotherapy within 4 weeks before the first dose, except for non-CNS palliative radiotherapy with a 2-week washout period; * History of systemic electrolyte imbalance or ectopic soft tissue calcification; * Clinically significant corneal or retinal disease; * Use of potent CYP3A4 inhibitors or inducers within 14 days or 5 half-lives before the first dose;