Cancer discovery
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The PI3Kδ inhibitor idelalisib was effective in heavily pretreated patients with mantle cell lymphoma.
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Vemurafenib, a RAF inhibitor, extends survival in patients with BRAF(V600)-mutant melanoma but activates extracellular signal-regulated kinase (ERK) signaling in RAS-mutant cells. In a patient with a BRAF(V600K)-mutant melanoma responding to vemurafenib, we observed accelerated progression of a previously unrecognized NRAS-mutant leukemia. ⋯ Antimelanoma and antileukemia responses have been maintained for nearly 20 months, as documented by serial measurements of tumor-derived DNA in plasma in addition to conventional radiographic and clinical assessments of response. These data support testing of intermittent ERK pathway inhibition in the therapy for both RAS-mutant leukemia and BRAF-mutant melanoma.