The aim of the present investigation is to test of the modulation obtained with denosumab as "priming" therapy before the start of chemotherapy and as concurrent therapy in a population of first line NPC recurrent/metastatic patients

Approximately 15-20% of the cancers recognize infectious agents as causal factors. Epstein Barr Virus (EBV) is considered carcinogenic to humans for haematological and solid neoplasms such as nasopharyngeal carcinoma (NPC). Oncogenic mechanisms linking EBV with NPC need to be better delineated. However, the well-defined patterns of EBV cancer cells infection, together with its encoded regulated genes in tumours offers an option for immunological therapeutic strategies.

Distant metastases, especially of the bone, occurs in up to half of patients with NPC. This underlines the importance of improving systemic disease control.

Intravenous bisphosphonates (BP) are effective treatments for skeletal-related events (SRE) in patients with bone metastases. BPs also showed antitumor properties in solid malignancies by inhibiting cancer cell proliferation, inducing apoptosis and affecting bone microenvironment, increasing progression free survival (PFS) and overall survival (OS).

In head and neck squamous cell cancer, RANKL expression has been observed and correlated with tumour differentiation and progression. RANKL expression is also found in tumour-infiltrating Tregs. Once expressed, RANKL regulates epidermal dendritic cells and increases the number of Tregs, thereby suppressing excessive response to environmental stimuli. In NPC, the role of Tregs has been described and implicated in EBV-associated carcinogenesis.

Although no direct evidence of denosumab activity in NPC cells are available, its target's effect on Tregs is at the base of an indirect effect to tackle cancer immune evasion. In this scenario, treatment with RANK and RANKL inhibitors will supposedly act as positive immunoregulator reducing bone events but also improving treatment effects.

RANK expression was confirmed on 17 metastatic relapses of NPC treated at Fondazione IRCCS Istituto Nazionale dei Tumori, Milano.

The recent introduction of denosumab, a new drug active on bone metastases, with a different mechanism of action compared to BPs, changed the scenario. Denosumab is a fully human monoclonal antibody preventing the binding of RANKL to its receptor on osteoclasts' membrane. Denosumab is formulated for SC injection and for oncology indications is administered at a dose of 120 mg Q4W. Denosumab (120 mg SC) is approved worldwide for the prevention of SREs in patients with bone metastases from solid tumors and for the treatment of adults and skeletally mature adolescents with GCTB.

The above premises warrant the investigation of the activity of denosumab - an antibody competing with RANK, enhancing increasing tumour-specific immunity through the blockade of RANKL-regulated Tregs.

Inclusion Criteria:

1. EBV related nasopharyngeal cancer

2. Detectable and quantifiable plasmatic EBV DNA

3. Recurrent and/or metastatic disease not suitable for curative treatment

4. PS < 2

5. Suitable for polychemotherapy

6. Age ≥ 18 years

7. Informed consent signed

8. Subject has adequate organ functions, evidenced by the following:

   1. AST (SGOT), ALT (SGPT) ≤ 2.5 x upper limit of normal range (ULN), or ≤ 5 x ULN range if liver metastasis present
   2. Total bilirubin ≤ 1.5 x ULN
   3. creatinine clearance 24/h > 50 mL/min
   4. Total serum calcium > 8.8 mg/dL
   5. Absolute neutrophil count ≥ 1.5 x 10*9 cells/L
   6. Platelets ≥ 100 x 10*9 cells/L
   7. Haemoglobin ≥ 9 g/dL

9. If of childbearing potential, willingness to use effective contraceptive method (Pearl Index < 1; e.g. oral contraceptive (pill), hormone spiral, hormone implant, transdermal patch, a combination of two barrier methods (condom and diaphragm), sterilisation, sexual abstinence) for the study duration and 5 months post-dosing.

10. Subject understands and voluntarily signs an ICF prior to any study-related assessments/procedures are conducted.

11. Subject is able to adhere to the study visit schedule and other protocol requirements

Exclusion Criteria:

1. Having received 1 or more chemotherapy line for recurrent/metastatic disease

2. Any residual CTCAE grade ≥ 2 toxicity

3. Subject has any other malignancy within 3 years prior to randomization, with the exception of adequately treated in situ carcinoma of the cervix, uteri, or non-melanoma skin cancer (all treatment of which should have been completed 6 months prior to enrolment), in situ squamous cell carcinoma of the breast, or incidental prostate cancer T1a, Gleason < 7, PSA <10 ng/ml.

4. Subject has had radiotherapy ≤ 4 weeks or limited field radiation for palliation ≤ 2 weeks prior to starting IP, and/or from whom ≥ 30% of the bone marrow was irradiated.

5. Having participated in another clinical trial or having received any investigational agent in the preceding 30 days before study entry.

6. Chronic systemic immunosuppressive therapy that cannot be interrupted during treatment study.

7. Subject has significant active cardiac disease within the previous 6 months including unstable angina or angina requiring surgical or medical intervention, significant cardiac arrhythmia, or New York Heart Association (NYHA) class 3 or 4 congestive heart failure.

8. Subject has a known or suspected hypersensitivity to study drugs.

9. Subject is pregnant or breast feeding.

10. Subject is receiving prohibited medication as per section 7.4.2 and suspension of such treatment is considered unsafe.

11. Subject has history of prior or current osteonecrosis of the jaw (ONJ).

12. Subject has history of prior irradiation to the mandible, specified as:

    Dose constraints to the mandible: Dmax = 70 Gy, V50 = 62 Gy and V60 = 20 Gy Mandible should be contoured as whole organ, with alveolar bone, excluding teeth

13. Subject has any other concurrent severe and/or uncontrolled medical condition that would, in the Investigator's judgment, contraindicate subject participation in the clinical study.

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