A Study to Evaluate Adze1.C in Participants With Metastatic Melanoma

Inclusion Criteria: * Male or female participants aged 18 years or older at Screening. * Histologically confirmed unresectable Stage IIIB to IV metastatic melanoma. * Refractory to, or unsuitable for, standard treatment options as determined by the investigator. * Not a suitable candidate for curative resection. * Presence of measurable disease per iRECIST (excluding irradiated lesions unless progression post-radiation is documented). * Presence of at least one injectable melanoma lesion and/or tumor-involved lymph node suitable for intratumoral administration. * ECOG performance status of 0 or 1 at Screening. * Stable visceral metastases and stable CNS metastases may be eligible if protocol-defined eligibility requirements are met. * Willing and able to provide written informed consent and comply with study procedures. Exclusion Criteria: * Uncontrolled intercurrent illness, including but not limited to: * Active systemic infection or fever ≥ 38°C within 5 days prior to Screening * Symptomatic congestive heart failure * NYHA Class III or IV heart failure * Unstable angina or arrhythmia * Leptomeningeal disease, active uncontrolled or symptomatic brain metastases, CNS haemorrhage, uncontrolled peri-tumoural oedema, or conditions associated with high risk of CNS inflammation * Psychiatric illness or social conditions that limit compliance * Visceral metastatic disease that is not clinically and radiographically stable or requires urgent medical intervention. * Immunocompromised status or known HIV infection with ongoing antiretroviral therapy. * Active or clinically significant liver disease, including: * Hepatitis B surface antigen (HBsAg) positive * Hepatitis C virus RNA positive * History of organ transplantation. * Prior treatment with adenovirus therapy. * Prior oncolytic virus treatment within 2 months of Screening. * Use of systemic immunosuppressants or other immune-modifying drugs must be discontinued 14 days prior to the first dose. * Use of cidofovir within 14 days of Adze1.C dosing. * Any other condition which, in the investigator's judgment, would make the participant inappropriate for the study.