What you are missing could matter: A rare, complex BRAF mutation affecting codons 599, 600, and 601 uncovered by next generation sequencing

Abstract

Testing for somatic mutations in tumor samples is becoming standard practice in a number of tumor types where targeted therapies are available. Since clinical care is dependent on the identification of the presence or absence of specific mutations, it is important that these mutations be identified consistently and accurately. Here we identify in a patient with metastatic melanoma a novel, complex mutation involving BRAF c.1798A>T (p.T599T), c.1799T>A (p.V600E), and c.1803A>T (p.K601N) that was identified by next generation sequencing but not by standard testing methods. The patient was started on a combination therapy inhibiting both BRAF and MEK, and demonstrated a dramatic clinical response. This case highlights the need for improved methods of mutation testing in tumor samples and exposes a pitfall in allele-specific testing methods that can be overcome using next generation sequencing.