LTX-315 in Patients With Transdermally Accessible Tumours as Monotherapy or Combination With Ipilimumab or Pembrolizumab

Inclusion Criteria: Arm A: (Recruitment completed) Arm B: * Unresectable metastatic disease (any tumor type) and conventional anti-tumor treatment is not appropriate. * Have at least one available lesion (cutaneous, sub-cutaneous, oral or lymph node) for injection between 1-3 cm longest diameter and one bystander lesion (non-injected). Arm C: * Have unresectable/metastatic diagnosis of malignant melanoma (histologically confirmed). * Have at least one available lesion (cutaneous, sub-cutaneous, oral or lymph node) for injection and biopsy which is between 1 and 3 cm in longest diameter. * Have had previous treatment with an anti-PD-1 antibody (as monotherapy or as part of combination (any combination) as 1st or 2nd line metastatic treatment). Arm D: * Have unresectable/metastatic diagnosis of triple negative breast cancer (histologically confirmed). * Have at least one available lesion (cutaneous, sub-cutaneous or lymph node) for injection and biopsy with a minimum longest diameter of 1 cm. * Have received between one and 4 prior systemic treatments for metastatic triple negative breast cancer. All arms: * Be willing to undergo repeat tumour biopsy and/or tumour resection procedures. * Have an ECOG Performance status (PS): 0 - 1. * Meet the following laboratory requirements: 1. Absolute neutrophil count (ANC) ≥ 1.5 x 109/L 2. Absolute lymphocyte count ≥ 0.8 x 109/L 3. Platelet count ≥ 75 x 109/L 4. Haemoglobin ≥ 9.0 g/dL 5. aPTT/PT within the institution's normal range 6. Total bilirubin level ≤ 1.5 x ULN 7. ASAT and ALAT ≤ 2.5 x ULN (≤5 x ULN if liver metastasis present) 8. Creatinine ≤ 1.5 x ULN 9. Albumin ≥ 30 g/L Exclusion Criteria: Arm A: (Completed) Arm B: * Have a history of systemic auto-immune disease requiring anti-inflammatory or immunosuppressive therapy within the last 3 months. Patients with history of autoimmune thyroiditis are eligible provided the patient requires only thyroid hormone replacement therapy and disease has been stable for ≥ 1 year. Arm C: * Have had prior therapy with ipilimumab or any other anti-CTLA-4 monoclonal antibody. * Have had BRAF/MEK inhibitors administered within 2 weeks prior to the study drug administration. * Have active systemic autoimmune disease; have had prior pneumonitis; have a history of severe hypersensitivity to another monoclonal antibody; are receiving immunosuppressive therapy; have a history of severe immune-related adverse reaction from treatment with a monoclonal antibody, defined as any Grade 4 or 3 toxicity requiring corticosteroid treatment (\> 10 mg/day prednisone or equivalent) for greater than 12 weeks. Arm D: * Have had prior therapy with an anti-PD-1 or anti-PD-L1 monoclonal antibody. * Have received cancer immunotherapy within 2 weeks prior to study drug administration or have not recovered from adverse events (to ≤ CTCAE grade 1) due to such agents. * Have active systemic autoimmune disease; have had prior pneumonitis; have a history of severe hypersensitivity to another monoclonal antibody; are receiving immunosuppressive therapy; and have a history of severe immune-related adverse reactions from treatment with a monoclonal antibody, defined as any Grade 4 or 3 toxicity requiring corticosteroid treatment (\> 10 mg/day prednisone or equivalent) for greater than 12 weeks. All arms: * Have received external radiotherapy or cytotoxic chemotherapy within 4 weeks prior to study drug administration, or have not recovered from adverse events (≤ CTCAE grade 1) due to agents administered more than 4 weeks earlier. Palliative radiotherapy to non-target lesions within 4 weeks prior to study drug administration is allowed. * Are currently taking any agent with a known effect on the immune system. Patients are allowed to be on a stable dose of corticosteroids (up to 10 mg daily prednisolone or equivalent) for at least 2 weeks prior to study drug administration (please see Appendix IV for prohibited medications). * Have any other serious illness or medical condition such as, but not limited to: 1. Uncontrolled infection or infection requiring antibiotics 2. Uncontrolled cardiac failure: Classification III or IV (New York Heart Association) 3. Uncontrolled systemic and gastro-intestinal inflammatory conditions 4. Bone marrow dysplasia * Have a known history of positive tests for HIV/AIDS, or have active hepatitis B or C (based on serology). * Are expected to need any other anti-cancer therapy or immunotherapy to be initiated during the study period. 15\. Have clinically active or unstable CNS metastases as assessed by the treating physician.