Inclusion criteria:
* Female or male patients, 18-65 years of age, with newly diagnosed, histologically confirmed p16- and HPV16-positive oropharyngeal squamous cell carcinoma with locoregional advanced disease including the following stages:
* T2N2-3, M0
* T3N0-3, M0
* T4N0-3, M0
* Primary tumour accessible for biopsy and intratumoural administration
* No evidence of distant metastatic disease (HPV16-positive secondary tumours are permissible)
* Karnofsky 100 - 70 (ECOG 0 or 1)
* Life expectancy of at least 6 months
* Normal screening ECG or screening ECG with no clinically significant findings requiring immediate treatment, as judged by the investigator
* Women of childbearing potential: Negative serum pregnancy test at screening
* Agree to use a reliable form of contraception until the end of the study treatment period.
* Provides written informed consent
Exclusion criteria:
* Distant metastases
* Secondary, not HPV16-associated, malignancy
* History of malignancy other than the target malignancy to be investigated in this trial unless a complete remission was achieved at least 2 years prior to study entry AND no additional therapy is required during the study period
* Clinically significant out of range haematological, renal or hepatic laboratory tests which cannot be explained by the underlying disease
* Any vaccination within 1 week before day 0
* Active significant viral infections including influenza, CMV, and EBV within 4 weeks before receiving study treatment
* Co-infection with hepatitis B, hepatitis C, or HIV or having other immune deficient states
* Influenza-like illness (ILI) within 4 weeks before day 0
* Known hypersensitivity to Tamiflu or any of its components
* Pregnancy, breastfeeding
* Serious, concomitant disorder, including active systemic infection requiring treatment
* Proven or suspected systemic lupus erythematosus, thyroiditis, inflammatory bowel disease including Crohn's disease or multiple sclerosis
* Immunosuppression including any concurrent condition requiring the continued use of systemic steroids, or the use of immunosuppressive agents, disease modifying doses of anti-rheumatic drugs (e.g., azathioprine, cyclophosphamide, cyclosporine, methotrexate), and biologic disease modifying drugs such as TNF-α inhibitors (e.g. infliximab, adalimumab or etanercept). Corticosteroids must be discontinued \> 4 weeks prior to day 0 of study medication administration. Eye drops or ear drops containing corticosteroids are permissible.
* Prior major surgery within 4 weeks before day 0
* Any current significant cardiac, hepatic or renal disease or history of clinically significant, medically unstable disease (e.g. chronic renal failure; angina, myocardial ischemia or infarction, congestive heart failure, cardiomyopathy, or clinically significant arrhythmias)
* Participation in another experimental protocol/use of investigational drug within two months before day 0
* Any condition that, in the judgment of the investigator, might prevent safe participation in the study or interfere with study objectives
* Unability to comply with the protocol requirements
