High Incidence of Naevi-associated BRAF Wild-type Melanoma and Dysplastic Naevi under Treatment with the Class I BRAF Inhibitor Vemurafenib
Daniela Göppner, Jan Müller, Sabine Krüger, Ingolf Franke, Harald Gollnick, Sven R. Quist
There is growing evidence that not only malign keratinocytic but also melanocytic tumours can arise during treatment with vemurafenib. During an on-going early access trial, 13 patients harbouring a BRAF-V600E mutation received vemurafenib (Zelboraf®) 960 mg twice daily to test the safety, tolerability, efficacy and response rate for advanced melanoma. Clinically or dermatoscopically suspicious cutaneous tumours under treatment with vemurafenib were excised. The BRAF-V600E status of confirmed new primary melanoma and dysplastic naevi was tested using a genetic mutation assay and immunohistochemistry. Four of the 13 patients (31%) developed 4 new naevi-associated malignant melanomas and 5 dysplastic naevi between 6 weeks and 6 months after the start of treatment. With the exception of one in situ melanoma, all tumours were BRAF wild-type. Immunohistochemistry revealed increased expression of ERK, pERK and active Rac1-GTP in the naevi-associated melanoma and dysplastic naevi. Careful and continuous skin examination, including dermoscopy, appears to be required during treatment with vemurafenib.