Chemotherapy for advanced gastric cancer: future perspective in Japan

Differences in clinical outcomes between advanced gastric cancer (AGC) in Asia and that in other regions have been discussed for a long time, although no major significant differences in molecular profiles have been reported. The anti-human epidermal growth factor receptor 2 antibody trastuzumab and the anti-vascular endothelial growth factor receptor 2 monoclonal antibody ramucirumab were both approved as a treatment for AGC on the basis of global phase 3 trials including Japan. In recent years, others new agents for treatment of AGC have been investigated in global or Asian studies. Randomized phase 2 trials in Japan showed a higher response rate to S-1 plus leucovorin and oxaliplatin than to standard S-1 plus cisplatin, which is the rationale for an ongoing phase 3 trial in Asia (SOLAR trial). A recent global phase 1 trial of the anti-programmed cell death 1 monoclonal antibody pembrolizumab showed similar efficacy results in Asian patients and non-Asian patients, which led to large global phase 2 and phase 3 studies. Although the perspective of treatment of AGC in the near future depends on the results of ongoing large clinical trials, individualized choice of treatment based on more detailed molecular information will become important.

Gastric cancer: somatic genetics as a guide to therapy

Gastric cancer is the leading cause of cancer-related mortality across the world, with poor prognosis and a median overall survival of ≤12 months for advanced stage gastric cancer. Environmental, genetic and other predisposing factors contribute to the development of gastric cancer and a predominant factor was found to be infection of Helicobacter pylori Advances in understanding the deranged signalling pathways that are critical for normal cellular homeostasis helped in the development of novel drugs that target specific proteins and pathways to curtail the growth of gastric cancer. Genetic studies revealed several single nucleotide polymorphisms, chromosomal aberrations and epigenetic alterations that likely play a major role in elevating the susceptibility to develop gastric cancer. Methylation pattern of specific genes may likely prove to be a valid biomarker for early detection of gastric cancer, but much progress is needed to establish specific markers. Important developments have been made in targeting human epidermal growth factor receptor-2 and vascular endothelial growth factor receptor 2 for treating advanced gastro-oesophageal junction cancer, using specific monoclonal antibodies. Lack of efficacy with regard to targeting other signalling pathways including mesenchymal-epithelial transition/hepatocyte growth factor and mammalian target of rapamycin is probably due to suboptimal patient selection for these clinical trials, which is probably due to the lack of appropriate biomarkers, to decide on responsive patient population. Besides the development of antagonists for the cell growth-related signalling pathways, advances are also being made to tackle gastric cancer by immunotherapies, targeting immune check-points, which may hold promise for better treatment options in future.

Phase II Trial of Sorafenib in Patients with Chemotherapy Refractory Metastatic Esophageal and Gastroesophageal (GE) Junction Cancer

PURPOSE

Vascular endothelial growth factor receptor (VEGFR2) directed therapies result in a modest survival benefit for patients with advanced esophageal and gastroesophageal (GE) junction cancer. Platelet-derived growth factor receptor (PDGFR) may contribute to escape from VEGFR2 inhibition. We evaluated the efficacy of sorafenib, a broad spectrum tyrosine kinase inhibitor targeting VEGFR2 and PDGFR as well as RET and RAF1, in patients with metastatic chemotherapy refractory esophageal and GE junction cancer.

PATIENTS AND METHODS

This phase II trial of sorafenib 400 mg twice daily enrolled chemotherapy refractory patients with metastatic esophageal and GE junction cancer with primary endpoint of progression-free survival (PFS) rate at two months. Secondary endpoints included overall survival, objective response rate and toxicity.

RESULTS

Among 34 patients, 8 week Kaplan-Meier estimated PFS was 61% (90%CI 45 to 73%). Median PFS is 3.6 months (95% CI 1.8 to 3.9 months), with median overall survival OS 9.7 months (95% CI 5.9 to 11.6 months). Grade 3 toxicities were uncommon and included hand foot skin reaction, rash, dehydration and fatigue. One patient (3%) with ongoing complete response and remains on trial for over 5 years. Whole exome sequencing of this tumor revealed mutations in many cancer-associated genes including ARID1A, PIK3CA, and TP53, and focal amplifications of HMGA2 and MET.

CONCLUSION

Sorafenib therapy results in disease stabilization and encouraging PFS in patients with refractory esophageal and GE junction cancer.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00917462.