A Study of Toripalimab as Consolidation Therapy After Postoperative Chemoradiotherapy in HNSCC

Inclusion Criteria:

* Postoperative with adverse prognostic factors in patients with locally advanced head and neck squamous cell carcinoma.
* Have received postoperative adjuvant radiotherapy (chemo) therapy, and the end of the treatment is not more than 2 months.
* Greater than or equal to 18 and less than 70 years of age at time of study entry.
* ECOG performance status of 0 or 1.
* Measurable disease as per RECIST 1.1.
* Screening labs must meet the following criteria and must be obtained within 14 days prior to registration:

  1. Adequate hepatic and renal function as demonstrated by

     1. Serum creatinine \< 1.5 X ULN or CrCl \> 40mL/min (if using the Cockcroft-Gault formula below):

        * Males: Creatinine CL (mL/min) = (Weight (kg) x (140 - Age))/(72 x serum creatinine (mg/dL)）
        * Females: Creatinine CL (mL/min) = (Weight (kg) x (140 - Age))/(72 x serum creatinine (mg/dL))x 0.85
     2. AST/ALT ≤ 3 x ULN
     3. Total Bilirubin ≤ 1.5 x ULN (except subjects with Gilbert Syndrome, who can have total bilirubin \< 3.0 mg/dL)
  2. Adequate bone marrow function as demonstrated by:

     1. Absolute Neutrophil Count \>1,500/µL
     2. Platelets \> 100 X 103/µL
     3. Hemoglobin \> 9.0 g/dL
* Women of reproductive potential should have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic gonadotropin \[HCG\]) within 7 days of study enrollment.
* Women of reproductive potential must use highly effective contraception methods to avoid pregnancy for 3 months after the last dose of study drugs; "women of reproductive potential" is defined as any female who has experienced menarche and who has not undergone surgical sterilization (hysterectomy or bilateral oophorectomy) or who is not postmenopausal; menopause is defined clinically as 12 months of amenorrhea in a woman over 45 in the absence of other biological or physiological causes; in addition, women under the age of 55 must have a documented serum follicle stimulating hormone (FSH) level less than 40 mIU/mL.
* Men of reproductive potential who are sexually active with women of reproductive potential must use any contraceptive method with a failure rate of less than 1% per year; men who are receiving the study medications will be instructed to adhere to contraception for 3 months after the last dose of study drugs; men who are azoospermic do not require contraception.
* Ability to understand and willingness to sign an IRB approved written informed consent document (or that of legally authorized representative, if applicable).
* Subject is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up.

Exclusion Criteria:

* Is currently participating in or has participated in a study of an investigational agent within 4 weeks of the first dose of treatment or has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier.
* Has had another known invasive malignancy within the previous 5 years （With the exception of basal cell carcinoma of the skin, carcinoma in situ of the cervix, and papillary carcinoma of the thyroid, which has been cured）.
* If subject received major surgery for any other reason, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.
* Active, known or suspected autoimmune disease.
* Has evidence of interstitial lung disease or active, non-infectious pneumonitis.
* Has an active infection requiring systemic therapy.
* Has received prior therapy with an anti-PD-1 antibody .
* A history of allergic reaction attributed to compounds of similar chemical or biologic composition to the treatment or other agents used in the study.
* Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.
* Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the pre-screening or screening visit through 23 weeks after the last dose of trial treatment.
* Has a known history of Human Immunodeficiency Virus (HIV) infection (HIV 1/2 antibodies).
* Has known active Hepatitis B or C.
* Known history of active TB ( bacillus tuberculosis ).