Sensitivity and Resistance of MET Exon 14 Mutations in Lung Cancer to Eight MET Tyrosine Kinase Inhibitors In Vitro.

BACKGROUND: MNNG HOS transforming gene (MET) exon 14 mutations in lung cancer, including exon 14 skipping and point mutations, have been attracting the attention of thoracic oncologists as new therapeutic targets. Tumors with these mutations almost always acquire resistance, which also occurs in other oncogene-addicted lung cancers. However, the resistance mechanisms and treatment strategies are not fully understood. METHODS: We generated Ba/F3 cells expressing MET exon 14 mutations by retroviral gene transfer. The sensitivities of these cells to eight MET-tyrosine kinase inhibitors (TKIs) were determined using a colorimetric assay. In addition, using N-ethyl-N-nitrosourea mutagenesis, we generated resistant clones, searched for secondary MET mutations, and then examined the sensitivities of these resistant cells to different TKIs. RESULTS: Ba/F3 cells transfected with MET mutations grew in the absence of interleukin-3, indicating their oncogenic activity. These cells were sensitive to all MET-TKIs except tivantinib. We identified a variety of secondary mutations. D1228 and Y1230 were common sites for resistance mutations for type I TKIs, which bind the active form of MET, whereas L1195 and F1200 were common sites for type II TKIs, which bind the inactive form. In general, resistance mutations against type I were sensitive to type II, and vice versa. CONCLUSIONS: MET-TKIs inhibited the growth of cells with MET exon 14 mutations. We also identified mutation sites specific for TKI types as resistance mechanisms and complementary activities between type I and type II inhibitors against those mutations. These finding should provide relevant clinical implication for treating patients with lung cancer harboring MET exon 14 mutations.

[A case report of the use of laparoscopic surgery to remove an adrenal tumor following resection of sigmoid colon cancer].

A 58-year-old woman underwent sigmoidectomy and partial cystectomy for sigmoid colon cancer following colostomy. The final staging of the tumor was T3, N1, tub2, M0, fStage IIIa. She received 6 courses of CapeOX (oxaliplatin 130mg/m², capecitabine 200mg/m²) as adjuvant chemotherapy, which was discontinued because of severe general fatigue. At the same time, an increase in the levels of serum carcinoembryonic antigen (CEA) was detected and abdominal computed tomography (CT) revealed an expanded adrenal mass. Since whole-body ¹8F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) showed no evidence of multiple organ metastases except for the right adrenal tumor, a solitary adrenal metastasis from sigmoid colon cancer was strongly suspected. Hence, colostomy closure and laparoscopic adrenalectomy were concurrently performed. Histological examination revealed non-functional adrenal adenoma. Therefore, laparoscopic surgery was a reasonable choice even in this complex case.

[A case of advanced hepatocellular carcinoma successfully treated by liver resection after complete response induced by sorafenib administration].

A 50-year-old man presented to our hospital with the chief complaint of right hypochondriac pain and a palpable tumor. Advanced hepatocellular carcinoma (HCC) and chronic hepatitis B infection were diagnosed and treated by twice-repeated transcatheterarterial chemoembolization (TACE) followed by administration of entecavir. Two months after the last TACE, alpha-fetoprotein(AFP)and protein induced by vitamin K absence or antagonistII (PIVKA-II) levels had elevated, and multiple small early enhancing nodules were detected on computed tomography(CT)scan. Based on his age and liver function (Child-Pugh score A5), a full dose of sorafenib (800 mg/day) was administered. The sorafenib dose was decreased after one month to 400mg/day because of hand-foot syndrome. Following sorafenib administration, the lesions shrank markedly, and complete response (CR) according to modified Response Evaluation Criteria In Solid Tumors(mRECIST)was achieved within 4 months. Six months after sorafenib treatment was begun, recurrent HCC was detected in segment 6, near the previously treated lesion. The decreased size of the main tumor and normalization of AFP levels allowed curative surgical resection. The patient was discharged 5 days after surgery and is currently treated with a half dose of sorafenib. Thirteen months after surgery, a small early enhancing lesion is visible on postoperative CT scan, but AFP and PIVKA-II levels are still keeping in a normal range. This case demonstrates that if sorafenib treatment is effective, then subsequent surgical treatment can be reconsidered in patients with advanced HCC responding to this combined therapy.