Inclusion Criteria:  Be willing and able to provide written informed consent Age ≥ 18 years Histologically- or cytologically-confirmed, relapsed/refractory, and metastatic or locally advanced head and neck, cervical, melanoma or non-small cell lung cancers. Other solid tumor types may be analyzed at the discretion of the Sponsor Able to provide archived tumor tissue or have existing data on TAAs, HPV status or HLA sub-type Willing to provide a saliva sample  Exclusion Criteria:  There are no exclusion criteria for this study.