• Patients aged 18 years or older at the time of informed consent, who are pathologically (histologically or cytologically) diagnosed with thymic carcinoma for primary or metastatic thymic lesions, are included. They are preferred to be positive for CD5 or c-KIT by immunohistochemical staining. For those with non-squamous epithelial carcinoma negative for p40 or p63, non-primary cases should be excluded based on their clinical and pathological findings. In addition, those with thymoma are excluded.

• Patients with unresectable advanced thymic carcinoma (equivalent to stage IVa or IVb of Masaoka-Koga classification), metastatic or recurrent, who have not been treated with systemic cancer chemotherapy.

• Or, in the case of stage III Masaoka-Koga classification, patients who are judged to be incapable of radical resection (R0 resection is not possible due to the combined resection of invasive lesions in surrounding organs (pericardial sac, lung, great vessels, etc.) or who are not eligible for curative treatment with chemoradiotherapy. A history of adjuvant chemotherapy and radiation therapy is acceptable for perioperative adjuvant therapy prior to the finding of recurrence. If platinum-containing cancer chemotherapy has been administered as adjuvant therapy, it is eligible if there is an interval of at least 24 weeks before registration.

• No symptomatic brain metastases, carcinomatous meningitis, or spinal metastases requiring radiotherapy or surgery

• No prior history of an antiangiogenetic agent targeting VEGFR for thymic carcinoma

• Not receiving radiotherapy within 14 days before registration Male participants

• A male participant must agree to use contraception as detailed in Appendix 3 of this protocol during the treatment period and for at least 135 days after the last dose of study treatment and refrain from donating sperm during this period.

• Female participants:

• A female participant is eligible to participate if she is not pregnant (see Appendix 3), not breastfeeding, and at least one of the following conditions applies:

∙ Not a woman of childbearing potential (WOCBP) as defined in Appendix 3 OR

‣ A WOCBP who agrees to follow the contraceptive guidance in Appendix 3 during the treatment period and for at least 120 days after the last dose of study treatment.

• The participant provides written informed consent for the trial

• Have measurable disease based on RECIST 1.1. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions

⁃ Meet the following criteria for Hepatitis B and C Patients with no history of HBV or HCV infection or who meet the following criteria 10.1 Hepatitis B positive subjects Participants who are HBsAg positive are eligible if they have received HBV antiviral therapy for at least 4 weeks and have an undetectable HBV viral load prior to registration.

⁃ Participants should remain on anti-viral therapy throughout the study intervention and follow local guidelines for HBV anti-viral therapy post-completion of the study intervention.

• 2 Participants with a history of HCV infection Participants are eligible if HCV viral load is undetectable at screening. Participants must have completed curative anti-viral therapy at least 4 weeks prior to registration.

⁃ Have provided archival tumor tissue sample or newly obtained core or excisional biopsy of a tumor lesion not previously irradiated. Formalin-fixed, paraffin-embedded (FFPE) tissue blocks are preferred to slides. Newly obtained biopsies are preferred to archived tissue.

⁃ Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1. Evaluation of ECOG is to be performed within 14 days before registration.

⁃ Have adequate organ function as defined in the following table (Table 8). Specimens must be collected within 14 days prior to registration.

⁃ Have a predicted life expectancy of \>12 weeks