Head And Neck Cancers Squamous Cell

The goal of this observational study is to learn about the prognostic value of circulation tumor emboli (CTM) in recurrent/metastatic head and neck cancer patients and also the changes of tumor microenvironment by different treatment modalities and drugs. The main questions it aims to answer are: 1. Investigators plan to correlate circulating tumor cells (CTC), circulating tumor emboli (CTM), and the composition of NK cells in CTM with clinical outcomes and establish their association with patient prognosis. 2. Investigators plan to understand the composition of NK cells and the immune cell components within CTM, and correlate these findings with treatment efficacy. Patients with recurrent/metastatic head and neck cancer will be included after informed consent and investigators will collect blood samples for analysis from them under the treatment provided by their primary care physicians.

The goal of this clinical trial is to assess the safety and tolerability of a virus replicon particle (VRP) encapsulated saRNA encoding IL-12 when injected into in head and neck cancer patients. The main questions being addressed are: The safety and tolerability of intratumoral (IT) injections of VRP-encapsulated saRNA encoding IL-12 (VLPONC-01) The tumor response to IT injections of VLPONC-01 The tumor response due to the combination of IT injections of VLPONC-01 and system IV administration of neoadjuvant pembrolizumab (anti-PD-1) treatment Researchers will compare neoadjuvant pembrolizumab alone to the combination therapy to see if the combination enhances tumor responses.