Inclusion Criteria:

        4.1.1 Age ≥ 18 years of age 4.1.2 ECOG Performance Status ≤ 1 (see section 12.4, Appendix
        D) 4.1.3 Biopsy proven HNSCC of the oropharynx, larynx, hypopharynx, or oral cavity Stage
        III-IVB as defined by American Joint Committee on Cancer (AJCC) T0-T4, N0 - N3, M0 4.1.4
        4.1.4 Must be considered Intermediate or High Risk

        Oropharynx Intermediate risk patients include those who have all of the following:

          -  HPV/p16 (+) disease, a significant tobacco smoking history (>10 pack years) and N2b-N3
             disease OR

          -  HPV (-) disease, ≤ 10 years of smoking and large tumors (T2-T3)

        Oropharynx High risk patients include those who are either:

          -  HPV (-) with >10 years of smoking, OR

          -  HPV (-), ≤ 10 years of smoking and T4 disease Oral Cavity, Larynx, Hypopharynx are
             considered high/intermediate risk (regardless of HPV, p16 or smoking status) 4.1.5
             Pre-treatment swallowing evaluation by speech and swallowing therapist, to included a
             modified barium swallow showing no significant impairment with swallowing oral
             medications.

        4.1.6 Required initial laboratory values:

          -  HgB ≥ 9.0 g/dL

          -  ANC≥1500/mm3

          -  Platelet count ≥ 100,000/mm3

          -  Serum creatinine ≤1.5 mg/dL and/or calculated creatinine clearance ≥50 mL/min(via
             Cockroft and Gault, see section 12.2, Appendix B)

          -  • Bilirubin within normal limits unless patient has Gilbert's disease and then
             bilirubin ≤ 3 x upper limits of normal (ULN)

          -  AST and ALT ≤ 3.0 x ULN 4.1.7 No prior definitive surgery for HNSCC 4.1.8
             Recommendation to undergo concurrent CRT, as determined by the treating physician,
             with a curative goal 4.1.9 Women of childbearing potential (WOCBP) should be willing
             to use 2 methods of birth control or be surgically sterile, or abstain from
             heterosexual activity for the course of the study. WOCBP are those who have not been
             surgically sterilized or have not been free from menses for > 1 year. The two birth
             control methods can be composed of: two barrier methods or a barrier method plus a
             hormonal method to prevent pregnancy. Subjects should start using birth control from
             the screening visit and continue throughout study mandated treatment and for 90 days
             after the final dose of study drug.

        The following are considered adequate barrier methods of contraception: diaphragm, condom
        (by the partner), copper intrauterine device, sponge, or spermicide. Appropriate hormonal
        contraceptives will include any registered and marketed contraceptive agent that contains
        an estrogen and/or a progestational agent (including oral, subcutaneous, intrauterine, or
        intramuscular agents).

        4.1.10 Male subjects should agree to use an adequate method of contraception starting with
        the first dose of study therapy and continuing through the last dose of study therapy and
        for 90 days after the final dose of study drug 4.1.11 Women of childbearing potential
        (WOCBP) must have negative pregnancy test within 72 hours prior to D1 of treatment 4.1.12
        Ability to swallow oral medications 4.1.13 As determined by the enrolling physician or
        protocol designee, ability of the patient to understand and comply with study procedures
        for the entire length of the study 4.1.14 Informed consent reviewed and signed

        Exclusion Criteria:

        4.2.1 Major surgical procedures ≤28 days prior to D1 of AZD1775 or minor surgical
        procedures ≤7 days; no waiting required following port-a-cath placement 4.2.2 Patients who
        have received prior radiation therapy for HNSCC 4.2.3 4.2.3 Myocardial infarction within 6
        months prior to enrollment or has New York Heart Association (NYHA) Class III or IV heart
        failure (see section 12.3, Appendix C), uncontrolled angina, severe uncontrolled
        ventricular arrhythmias, or electrocardiographic evidence of acute ischemia or active
        conduction system abnormalities. Prior to study entry, any ECG abnormality at Screening has
        to be documented by the investigator as not medically relevant.

        • ECG ≤450 msec for males and ≤470 msec for females required on screening ECG 4.2.4 AST or
        ALT ≥3 x ULN (upper limit of normal) and total bilirubin ≥2 x ULN please refer to Appendix
        12.5 'Actions required in cases of combined increase of Aminotransferase and Total
        Bilirubin - Hy's Law', for further instructions 4.2.5 Not deemed a candidate for concurrent
        CRT for medical reasons, such as uncontrolled infection (including HIV), or uncontrolled
        diabetes mellitus which in the opinion of the treating physician, would make this protocol
        unreasonably hazardous for the patient.

        4.2.6 Not willing to avoid grapefruit, grapefruit juices, grapefruit hybrids, Seville
        oranges, pummelos, and exotic citrus fruits from 14 days prior to the dose of study
        medication, throughout the study, and until 2 weeks after the last dose of AZD1775 due to
        potential CYP3A4 interaction with the study medication. Orange juice is allowed.

        4.2.7 Patient has had prescription or non-prescription drugs or other products (ie,
        grapefruit juice) known to be moderate to strong inhibitors or inducers of CYP3A4, which
        cannot be discontinued 14 days before Day 1 of dosing and withheld throughout the study
        until 14 days after the last dose of AZD1775 (see section 12.5 Appendix E).
        Co-administration of aprepitant and fosaprepitant during this study is prohibited.
        Co-treatment with weak inhibitors of CYP3A4 is allowed.

        4.2.8 AZD1775 is an inhibitor of breast cancer resistance protein (BCRP). The use of
        statins including atorvastatin which are substrates for BCRP are therefore prohibited and
        patients should be moved on to non-BCRP alternatives.

        4.2.9 Unable or unwilling to discontinue use of any sensitive CYP3A4 substrates and CYP3A4
        substrates with a narrow therapeutic window (see section 12.5, Appendix E) 4.2.10
        Impairment of gastrointestinal (GI) function or GI disease that may significantly alter the
        absorption of AZD1775 (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea,
        malabsorption syndrome, or small bowel resection) 4.2.11 Receiving or less than 21 days
        since receiving any other concurrent cytotoxic, biologic agent(s) or investigational agent
        4.2.12 Patients with a "currently active" second malignancy other than non-melanoma skin
        cancers, non-invasive bladder cancer, "low risk" adenocarcinoma of the prostate and
        carcinoma in situ of the cervix. Patients are not considered to have a "currently active"
        malignancy if they have completed therapy and are free of disease for ≥ 2 years.

        4.2.13 Pregnant or nursing