Blood test could guide treatment order in metastatic melanoma

A blood sample is offering a possible new way to choose the order of treatments for people whose melanoma has spread. Researchers from Karolinska Institutet analyzed 81 patients with metastatic melanoma and a BRAF mutation in the international SECOMBIT trial, which compared three treatment sequences involving immunotherapy and targeted drugs.

The marker is called TKa, short for thymidine kinase activity. It provides information about how quickly tumor cells grow and divide. Before treatment began, patients with high TKa levels had shorter survival and saw their disease progress sooner than patients with low levels. After five years, around 71% of patients with low TKa levels were still alive, compared with approximately 37% of those with high levels.

The result also points toward a more tailored treatment sequence. Patients with high TKa levels appeared to benefit from a short initial period of targeted therapy before immunotherapy. For patients with low TKa levels, starting with immunotherapy produced better outcomes. Around half of patients with metastatic melanoma carry a BRAF mutation, and both treatment approaches are available to them.

And so, concretely? A TKa test could one day help doctors decide which therapy to start first and track whether treatment is working, since the researchers found that levels often increased when the disease worsened. The study, led by Hildur Helgadottir with Mattias Bergqvist at Biovica, is the first clinical trial to evaluate TKa in metastatic melanoma, but Helgadottir says further studies are needed before the method can be used in routine care.