Decitabine Treatment in HPV-Induced Anogenital and Head and Neck Cancer Patients After Radiotherapy or as Novel Late Salvage

Inclusion Criteria: 1\. Patients meeting all of the following criteria will be considered for admission to the trial: Patients with an HPV-induced (will be assumed if both HPV DNA and immunohistochemical overexpression of p16INK4a is detected in tumor tissue) cancer of the * anus * vulva * vagina * uterine * cervix * penis or * oropharynx/oral cavity and * Stratum 1: Patients having received standard, definitive chemoradiotherapy according to current national guidelines with curative intent and being at high risk for disease recurrence (patients are considered at high risk if they display a positive nodal status of their cancer (anogenital HPV-induced tumor) or if the tumor is locally advanced and/or if they display a positive nodal status with extracapsular extension (head and neck HPV-induced tumor). Study therapy (as additional therapy to standard chemoradiation) will start after a time interval of 6-8 weeks after finishing chemoradiotherapy. * Stratum 2: Patients with non-curative and progressive disease having received all standard, national approved systemic therapies (according to current, national guidelines with regard to the specific tumor entity), and/or presently not eligible for a respective therapy, and/or refused respective therapy. Study treatment thereby represents a potential palliative, "last-line" systemic therapy option (late salvage). * Ability of patient to understand character and individual consequences of the clinical trial * Postmenopausal or evidence of non-childbearing status. For women of childbearing potential: negative urine pregnancy test at baseline and highly effective forms of contraception (see 6.5) in place thereafter as well as confirmed negative urine pregnancy test prior to treatment on day 1 of every cycle and at end of treatment period Evidence of childbearing potential is defined as: * Fertile, following menarche and until becoming post-menopausal unless permanently sterile Postmenopausal or evidence of non-childbearing status is defined as: o Amenorrheic for 1 year or more without an alternative medical cause following cessation of exogenous hormonal treatments PLUS Follicle stimulating hormone (FSH) levels in the postmenopausal range in women not using hormonal contraception or hormonal replacement therapy * Surgical sterilisation (bilateral oophorectomy, hysterectomy or bilateral salpingectomy) A man is considered fertile after puberty unless permanently sterile by bilateral orchidectomy. * Female patients of child bearing potential and male patients with partners of child bearing potential, who are sexually active, must agree to the use of highly effective forms of contraception. This should be started from the signing of the informed consent and continue throughout period of taking study treatment and for 6 months (female study participants)/ 3 months (male study participants) after last dose of study drug. * Evidence of a personally signed and dated informed consent document indicating that the patient (or a legally acceptable representative) has been informed of all pertinent aspects of the study (must be given before enrolment in the trial) * Patients who are willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures. Exclusion Criteria: Patients presenting with any of the following criteria will not be included in the trial: * Age \<18 years * Grade 3 neutropenia with Neutrophiles \< 1/nl, thrombocytopenia with thrombocytes \< 50/nl and/ or anemia with Hgb \<8.0 g/dL * Active infections requiring anti-infective treatment * Bleeding disorders (e.g. Hemophilia, von Willebrandt disease, congestive deficiency of any coagulation factor (e.g. factor V, X), Immune thrombocytopenia (ITP) thrombocytopathies (e.g. Bernard-Soulier-syndrome drug induced bleeding disorders * Insulin-dependent and unregulated diabetes * Grade 3/4 renal failure with a GFR \< 60 ml/min * Liver cirrhosis Child C • History of cardiac diseases * Pregnancy and/ or lactation • History of treatment with DNA Methyltransferase Inhibitors (DNMTs) * Participation in other clinical trials involving another investigational agent within 4 weeks prior to first treatment of this study * ECOG performance status \>2 * History of hypersensitivity to the investigational medicinal product or to any drug with similar chemical structure or to any excipient present in the pharmaceutical form of the investigational medicinal product * History of other malignancies (except basal cell carcinoma) in the past 5 years No patient will be allowed to enroll in this trial more than once.