A Clinical Trial Assessing BT-001 Alone and in Combination With Pembrolizumab in Metastatic or Advanced Solid Tumors

This study will include 3 parts: * Phase I, Part A: Repeated intra-tumoral (IT) administrations of BT-001 as a single agent, in patients with metastatic/advanced solid tumors; dose-escalation will be employed. * Phase I, Part B: Repeated IT administrations of BT-001 in combination with intravenous (IV) infusions of pembrolizumab in patients with metastatic/advanced soft tissue sarcoma (STS), Merkel cell carcinoma (MCC), melanoma, triple negative breast cancer (TNBC) or non-small cell lung cancer (NSCLC).. * Phase IIa: Repeated IT administrations of BT-001 in combination with IV infusions of pembrolizumab in several cohorts of patients with defined metastatic or advanced solid tumor conditions.