Circulating Tumour DNA Guided Adaptive BRAF and MEK Inhibitor Therapy

The goal of this clinical trial is to investigate adaptive therapy in late-stage cutaneous melanoma. The main question it aims to answer are:

If the patient having breaks in their treatment allows the less resistant cells to continue to grow, this would result in a tumour with a lower proportion of resistant cells, making the tumour less resistant to the treatment, an increasing the time it takes for the disease to progress?

Participants will

* Receive their allocated treatment regimen until their cancer progresses, they or their doctor withdraw them from the study, or until the study ends, whichever happens first. * Attend fortnightly visits to hospital. * Complete EORTC QLQ-C30 and PRO-CTCAE questionnaires, prior to treatment, every 12 weeks and at the point of cancer progression, to assess quality of life.

Researchers will compare the adaptive therapy participant arm with a standard of care arm to answer the research question described above.