Inclusion Criteria:  Provide written informed consent to participate Aged 18 years or over One of eleven histologically or cytologically confirmed metastatic/advanced carcinomas or adenocarcinomas that has progressed after at least one line of systemic therapy and are incurable by local therapy At least one measurable site of disease according to RECIST v1.1 criteria Prior treatment with a PD-1/PD-L1 inhibitor Tumour accessible for biopsy, and patient willing to consent to tumour biopsies Ability to comply with study procedures in the Investigator's opinion ECOG performance status 0 or 1 Predicted life expectancy of ≥6 months Adequate lung reserve Adequate renal function Adequate hepatic function Adequate bone marrow/haematological function Coagulation profile within the normal range Meeting reproductive status requirements  Exclusion Criteria:  Prior or planned allogeneic or autologous bone marrow or tissue/organ transplantation Splenectomy Active infections requiring antibiotics, physician monitoring or recurrent fevers (>38.0˚C) associated with a clinical diagnosis of active infection Known history of hepatitis B (defined as HBsAg reactive) or known active hepatitis C virus (defined as HCV RNA [qualitative] is detected) infection. Known history of HIV infection (no testing for HIV, hepatitis B or hepatitis C is required unless mandated by local health authority). Use of the following antiviral agents: ribavirin, adefovir, lamivudine or cidofovir within 10 days prior to the first dose of study treatment; or pegylated interferon (PEG-IFN) in the 4 weeks before the first dose of study treatment Patients who have active autoimmune disease that has required systemic therapy in the past 2 years, are immunocompromised in the opinion of the Investigator, or are receiving chronic systemic immunosuppressive treatment. Treatment with any live, live-attenuated or COVID-19 vaccine in the 30 days before first dose of study drug Treatment with any other vaccine (including known non live/live-attenuated or non-adenoviral COVID-19 vaccines) in the 7 days before first dose of study drug History of prior Grade 3-4 acute kidney injury or other clinically significant renal impairment History of clinically significant interstitial lung disease or non-infectious pneumonitis/interstitial lung disease that required steroids Lymphangitic carcinomatosis Any of the following in the 3 months before the first dose of study treatment: Grade 3 or 4 gastrointestinal bleeding or risk factors for gastrointestinal bleeding, infectious or inflammatory bowel disease, history or evidence of haemoptysis, significant cardiovascular or cerebrovascular event and any history of bleeding requiring an investigative procedure (e.g. endoscopy), transfusion or hospitalization in the 12 months before the first dose of study treatment Any of the following in the 12 months before the first dose of study treatment: pulmonary embolism, deep vein thrombosis or other uncontrolled thromboembolic event Tumour location/extent considered by the Investigator to present a significant risk of a tumour flare, or necrosis were to occur (e.g. an initial increase in tumour size that may lead to intestinal, airway or ureter obstruction, or penetrating tumour infiltration of major blood vessels, or other hollow organs potentially at risk of perforation)  Use of the following prior therapies/treatments:  Treatment with any other enadenotucirev-based virus (parent virus or transgene-modified variants), or anti-CD40 antibody at any time Radiation therapy to the lung that is >30Gy within 6 months of the first dose of trial treatment Treatment with an investigational or licensed anti-cancer monoclonal antibody (mAb), immune checkpoint inhibitor, immune stimulatory treatment or other biological therapy in the 28 days prior to the first dose of study treatment (Prior anti-PD-1 / PD-L1 therapy is permitted without a 'washout' phase) Treatment with an investigational or licensed chemotherapy, targeted small molecule or other investigational drug in the 14 days or five half-lives (whichever is shorter) before the first dose of study treatment Major surgery in the 28 days before the first dose of study treatment or radiation therapy in the 14 days before the first dose of study treatment Bisphosphonate therapy or treatment with Receptor Activator of Nuclear factor Kappa-Β (RANK)-ligand inhibitors for metastatic bone disease is permitted All toxicities attributed to prior anti-cancer therapy other than alopecia must have resolved to Grade 1 or baseline Discontinuation from prior treatment with an anti-PD-1 or anti-PD-L1/PD-L2 agent or an agent directed to another stimulatory or co-inhibitory T-cell receptor, due to a Grade ≥3 immune-related AE Known allergy or hypersensitivity to NG-350A transgene, pembrolizumab and/or any of its excipients or other monoclonal antibodies Other prior malignancy active within the previous 3 years, except for local or organ confined early stage cancer that has been definitively treated with curative intent, does not require ongoing treatment, has no evidence of residual disease and has a negligible risk of recurrence and is therefore unlikely to interfere with the primary and secondary endpoints of the study, including response rate and safety Known active central nervous system metastases and/or carcinomatous meningitis. History or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the participant's participation for the full duration of the study, or is not in the best interest of the participant to participate, in the opinion of the treating investigator