Surprising finding in rare form of melanoma get patients closer to personalised medicine
11 January 2018
Researchers at Melanoma Institute Australia have demonstrated that immunotherapy is highly effective in treating a rare form of melanoma – a result that is surprising due to the nature of the tumour.
Desmoplastic melanoma accounts for less than 4% of melanomas in Australia and is typically found on chronically sun-damaged skin of older individuals. The tumour is characterised by dense fibrous connective tissue – a characteristic that was thought to physically limit immune cells effectively penetrating the tumour to destroy it.
However, the study – published today in the prestigious journal Nature – has revealed that desmoplastic melanomas are actually highly responsive to single agent anti-PD-1 therapy (pembrolizumab or nivolumab).
The study showed that 70% of patients with advanced desmoplastic melanoma responded to the immunotherapy – a response rate that is significantly higher than any other subtype of melanoma (typically 33–40%). One-third of patients had a complete response to treatment and their tumours did not progress at all (median follow up of 22 months).
This finding is likely to have implications for how we treat desmoplastic melanoma in the future. By gaining a deeper understanding of which subtypes of melanoma are more responsive to treatment, we can get one step closer to more effective and personalised medicine.
The study also found a higher percentage of PD-L1 positive cells in the desmoplastic melanoma tumours compared with non-desmoplastic melanomas, which helps explain why so many patients respond to this type of therapy.
A genetic analysis was also conducted and found many genes were mutated in a pattern that corresponds to damage by ultraviolet (UV) light. Whole-exome sequencing also revealed gene mutations that are also characteristic of NF1 subtype melanoma.