Frequent Coamplification of Receptor Tyrosine Kinase and Downstream Signaling Genes in Japanese Primary Gastric Cancer and Conversion in Matched Lymph Node Metastasis

Objective: To establish the gene copy number status of receptor tyrosine kinase (RTK) and downstream signaling (DSS) genes genes in primary gastric cancer (primGC) and matched lymph node metastases (LNmet). Background: Evidence suggests that coamplification between RTKs and DSSs and conversion between primGC and LNmet are associated with resistance to targeted therapy. Methods: DNA from 237 Japanese primGC and 103 matched LNmet was analyzed using a newly developed multiplex ligation-dependent probe amplification (MLPA) probemix to investigate RTK (EGFR, HER2, FGFR2, and MET) and DSS (PIK3CA, KRAS, MYC, and CCNE1) gene copy number status. Results were compared between primGC and LNmet and related to clinicopathological data including survival. Results: A total of 150 (63%) primGC had either RTK or DSS amplification. DSS coamplification was more frequent than RTK coamplification in primGC and LNmets. Moreover, 70 (30%) GC showed a disconcordant RTK and/or DSS gene copy number status between primGC and LNmet, most common was negative conversion for DSS genes (n=40 GC). The presence of RTK amplification in primGC was related to poorer survival in univariate analysis (P=0.04). Conclusions: This is the first and most comprehensive study in gastric cancer investigating the concordance between gene copy number status of targetable RTKs and downstream signaling oncogenes in primGC and LNmets. Future studies need to establish whether the relative high frequency of RTK and DSS coamplification and/or the relative high rate of negative conversion in LNmet can potentially explain recent failures of RTK targeted therapy in gastric cancer patients

Narrowing the knowledge gaps for melanoma

Cutaneous melanoma originates from pigment producing melanocytes or their precursors and is considered the deadliest form of skin cancer. For the last 40 years, few treatment options were available for patients with late-stage melanoma. However, remarkable advances in the therapy field were made recently, leading to the approval of two new drugs, the mutant BRAF inhibitor vemurafenib and the immunostimulant ipilimumab. Although these drugs prolong patients' lives, neither drug cures the disease completely, emphasizing the need for improvements of current therapies. Our knowledge about the complex genetic and biological mechanisms leading to melanoma development has increased, but there are still gaps in our understanding of the early events of melanocyte transformation and disease progression. In this review, we present a summary of the main contributing factors leading to melanocyte transformation and discuss recent novel findings and technologies that will help answer some of the key biological melanoma questions and lay the groundwork for novel therapies