HER2 Transmembrane Domain (TMD) Mutations (V659/G660) That Stabilize Homo- and Heterodimerization Are Rare Oncogenic Drivers in Lung Adenocarcinoma That Respond to Afatinib.

INTRODUCTION: Erb-b2 receptor tyrosine kinase (HER2) transmembrane domain (TMD) mutations (HER2V659E, HER2G660D) have previously been identified in lung adenocarcinomas, but their frequency and clinical significance is unknown. METHODS: We prospectively analyzed 8551 consecutive lung adenocarcinomas using hybrid capture-based comprehensive genomic profiling (CGP) at the request of the individual treating physicians for the purpose of making therapy decisions. RESULTS: We identified 15 cases (0.18%) of HER2 TMD mutations (HER2V659E/D, HER2G660D) through CGP of 8551 lung adenocarcinomas. HER2 TMD mutations were mutually exclusive from HER2 kinase domain mutations and other oncogenic drivers in lung adenocarcinoma. Only two cases with HER2 TMD mutations (13%) had concurrent Erb-b2 receptor tyrosine kinase 2 gene (HER2) amplification. Structural analysis of HER2 TMD association revealed that mutations at positions V659 and G660 to the highly polar residues glutamic acid, aspartic acid, or arginine should stabilize homodimerization and heterodimerization of HER2 in the active conformation. Treatment with afatinib, a pan-HER inhibitor, resulted in durable clinical response in three of four patients with lung adenocarcinoma, with two harboring HER2V659E and one with double HER2V659E/G660R mutations. HER2 TMD mutations (V659 and G660) are found in other non-NSCLC malignancies, and analogous TMD mutations are also found in EGFR, HER3, and HER4. CONCLUSION: HER2 TMD mutations represent rare but distinct targetable driver mutations in lung adenocarcinoma. CGP capable of detecting diverse HER2 alterations, including HER2 TMD mutations, should be broadly adopted to identify all patients who may benefit from HER2-targeted therapies.

A Case of Tumor Lysis Syndrome in a Patient with Pancreatic Adenocarcinoma Treated with Low-Dose Gemcitabine.

BACKGROUND: Tumor lysis syndrome (TLS) is a common adverse consequence of treatment of high-grade hematologic malignancies that has been known to occur rarely in some solid tumors, including small cell lung cancer, breast cancer, colorectal cancer, neuroblastoma, ovarian cancer, and hepatocellular carcinoma. CASE REPORT: We present a case of TLS in a patient with pancreatic adenocarcinoma treated with one small dose of gemcitabine. To our knowledge, this phenomenon has only been described once prior in the medical literature and never with a reduced dose of chemotherapy. CONCLUSION: This case reveals the need for heightened awareness of TLS in patients with solid tumors, especially in patients with pancreatic adenocarcinoma.