Phase 1 Open Label Trial of MST-0312 Alone and in Combination in Subjects With Solid Malignancies

Inclusion Criteria: * Male and female subjects of any ethnic origin, aged 18 years and over. * Must have given written informed consent and must be able to understand the full nature and purpose of the trial, including possible risks and adverse effects. * Subject must have a solid malignancy (non-small cell lung cancer (NSCLC), melanoma, bladder cancer, colorectal cancer (CRC) and triple negative breast cancer (TNBC)). * An ECOG performance status of 0 or 1 with no deterioration over the previous two weeks. * Willing to permit access to stored historical tumour tissue and prior tumour radiological assessments, cancer treatment history, including response to treatment, and tumour biomarker data, where available. * Willing and able to comply with all scheduled visits, treatment plans, laboratory tests, and other trial procedures. Exclusion Criteria: * Any unresolved toxicity (except alopecia) from prior therapy of ≥2 CTCAE Grade. * Active or documented history of autoimmune disease requiring interventional therapy. * Active infection requiring systemic antibiotic, antifungal, or antiviral medication within 14 days prior to first dose of IMP. * Male or female subjects of childbearing potential unwilling to comply with contraception requirements.