Inclusion Criteria:

          -  Be willing and able to provide written informed consent for the trial.

          -  Males or females aged ≥18 years at screening.

          -  Have an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.

          -  Have histologically- or cytologically-confirmed HNSCC.

          -  Have recurrent disease not amenable to curative treatment with local or systemic
             therapy, or metastatic (disseminated) HNSCC of the oral cavity, oropharynx,
             hypopharynx, or larynx that is considered incurable by local therapies.

          -  Having prior platinum failure.

        Exclusion Criteria:

          -  Subjects with carcinoma of the nasopharynx, squamous cell carcinoma of unknown primary
             origination, squamous cell carcinoma that originates from the skin and salivary gland
             or paranasal sinus, nonsquamous histologies.

          -  Have disease that is suitable for locoregional treatment administered with curative
             intent or refuses curative intent.

          -  Have no more than 15% body weight loss due to the underlying condition in the last 3
             months from signing of informed consent in Part 1 of the study and from randomization
             in to Part 2.

          -  Are currently participating in or have participated in a study of an investigational
             agent or are using an investigational device within 4 weeks prior to the first dose of
             trial treatment.

          -  Were previously treated with 3 or more lines of systemic therapies administered for
             recurrent and/or metastatic disease.