PD-1 Inhibitor and Anlotinib Combined With Multimodal Radiotherapy in Recurrent or Metastatic Anaplastic Thyroid Cancer

Inclusion Criteria:

1. Age 18 years or above.
2. Patients with pathologically confirmed Undifferentiated thyroid carcinoma and meet the following conditions:

   1. Were diagnosed with distant metastasis;
   2. Were intolerant to or failed first-line treatment.
3. Eastern Cooperative Oncology Group (ECOG) performance status 0-2.
4. Expected life is greater than or equal to 12 weeks.
5. There is at least one measurable lesion according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
6. Adequate organ and bone marrow function:

   1. Absolute neutrophil count ≥ 1.5 × 10\^9/L, hemoglobin ≥ 80 g/L, platelets ≥ 80 × 10\^9/L;
   2. ALT, AST and ALP \< 2.5× upper limit of normal (ULN), total bilirubin ≤ 2×ULN; albumin≥ 2.8 g/dL；
   3. Creatinine clearance ≥ 60 ml/min;
   4. INR≤ 1.5, APTT≤ 1.5×ULN.
7. Written informed consent.

Exclusion Criteria:

1. Existing tumor-related hemorrhage。
2. History of other malignancies (except for the history of malignant tumors that have been cured and have not recurred within 5 years, such as skin basal cell carcinoma, skin squamous cell carcinoma, superficial bladder cancer, in situ cervical cancer, and gastrointestinal mucosal cancer, etc.）
3. Have an active autoimmune disease requiring systemic treatment or a documented history of clinically severe autoimmune disease.
4. Any history of allergic disease, severe hypersensitivity reaction to drugs, or allergy to the study drug components.
5. Any prior therapy with:

   1. Toxicity from prior antitumor therapy has not recovered to ≤ CTCAE Version 5.0 Grade 1 or the level specified by the inclusion/exclusion criteria.
   2. Antitumor vaccine;
   3. Any active vaccine against infectious disease within 4 weeks prior to the first dose or planned during the study period;
   4. Major surgery or serious trauma within 4 weeks before the first dose;
6. With serious medical diseases, such as grade II and above cardiac dysfunction (NYHA criteria), ischemic heart disease, supraventricular or ventricular arrhythmia, poorly controlled diabetes mellitus, poorly controlled hypertension, echocardiographic ejection fraction \< 50%, etc.
7. With interstitial pneumonitis, non-infectious pneumonitis, active pulmonary tuberculosis, or a history of pulmonary tuberculosis infection that was not controlled by treatment.
8. With hyperthyroidism, or organic thyroid disease.
9. With active infection, or unexplained fever during the screening period or 48 hours before the first dose.
10. With active hepatitis B or C, or known history of positive HIV test, or acquired immunodeficiency syndrome.
11. History of a clear neurological or psychiatric disorder.
12. History of drug abuse or alcohol abuse.
13. Women who are pregnant or breastfeeding, or have a reproductive plan from the screening period to 3 months after the end of the study, or have sex without contraceptive measures, or are unwilling to take appropriate contraceptive measures.
14. Received any investigational drug within 4 weeks prior to the first dose, or concurrently enrolled in another clinical trial.
15. Any other factors that are not suitable for inclusion in this study judged by investigators.