The purpose of this study is to test a study drug called patritumab. Patritumab may work when combined with other medications that are approved in the UK for treating Squamous Cell Carcinoma of the Head and Neck (SCCHN), called cetuximab, cisplatin or carboplatin. It is hoped that patritumab may have some benefit in treating patients with cancer. This study will help identify how much patritumab can be given in combination with cetuximab, and cisplatin or carboplatin. This study will show how safe and how well tolerated patritumab is when these medications are given together.

The trial will be performed in two "phases" (Periods):

Period 1: Initial phase in which the recommended phase 2 dose (RP2D) is determined

Period 2: Extension phase in which participants who are deriving benefit (stable disease or better) will have the opportunity to continue treatment at the discretion of the Investigator

Inclusion Criteria:

• Histologically or cytologically confirmed recurrent disease or metastatic SCCHN originating from the oral cavity, oropharynx, hypopharynx, and larynx
• Has documented disease recurrence following prior treatment
• Has Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
• Has adequate hematological function, per protocol
• Has adequate renal function, per protocol
• Has adequate hepatic function, per protocol
• Has prothrombin time (PT) or partial thromboplastin time (PTT) within 1.5 x upper limit of normal (ULN)
• Has a negative serum pregnancy test performed within 14 days prior to enrollment (where required by local regulations, test may be required within 72 hours prior to enrollment), if a woman of child-bearing potential
• Agrees to use double-barrier contraceptive measures, oral contraception, or avoidance of intercourse during the study and for 90 days after last study dose received, if of child-bearing potential
• Is willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures

Exclusion Criteria:

• Has left ventricular ejection fraction (LVEF) < 50%
• Has received prior epidermal growth factor receptor (EGFR) targeted regimen
• Has received prior anti-HER2, anti-HER3, or anti-HER4 therapy
• Has received prior treatment for recurrent/metastatic disease
• Has history of other malignancies, except adequately treated non-melanoma skin cancer, curatively treated in-situ disease, or other solid tumors curatively treated with no evidence of disease for ≥ 5 years
• Has known history of and active brain metastases
• Has uncontrolled hypertension (systolic > 160 mm Hg or diastolic > 100 mm Hg)
• Has clinically significant electrocardiogram (ECG) changes
• Has had myocardial infarction within 1 year before enrollment, symptomatic congestive heart failure (New York Heart Association >Class II), unstable angina, or unstable cardiac arrhythmia requiring medication
• Had platinum-containing drug therapy/chemotherapy with radiotherapy < 6 months before study drug treatment
• Had therapeutic or palliative radiation therapy or major surgery within 4 weeks before study drug treatment.
• Participated in clinical drug trials within 4 weeks before study drug treatment or is currently participating in other investigational procedures
• Has uncontrolled infection requiring intravenous (IV) antibiotics, antivirals, or antifungals, known human immunodeficiency virus (HIV) infection, active hepatitis B or C infection, or is undergoing medical treatment for infection
• Has uncontrolled type 1 or 2 diabetes mellitus
• Has known hypersensitivity or allergic reaction against any of the components of the trial treatment
• Is pregnant, breastfeeding, or unwilling/unable to use acceptable contraception
• Has psychological, social, familial, or geographical factors that would interfere with study participation or follow up