Targeted therapies in gastric cancer and future perspectives

Advanced gastric cancer(AGC) is associated with a high mortality rate and, despite multiple new chemotherapy options, the survival rates of patients with AGC remains poor. After the discovery of targeted therapies, research has focused on the new treatment options for AGC. In the last two decades, many targeted molecules were developed against AGC. Currently, two targeted therapy molecules have been approved for patients with AGC. In 2010, trastuzumab was the first molecule shown to improve survival in patients with HER2-positive AGC as part of a first-line combination regimen. In 2014, ramucirumab was the second targeted molecule to improve survival rates and was suggested as treatment for patients with AGC who had progressed after firstline platinum plus fluoropyrimidine with or without anthracycline chemotherapy. Ramucirumab was the first targeted therapy acting as a single agent in patients with advanced gastroesophageal cancers. Although these two molecules were introduced into clinical use, many other promising molecules have been tested in phase Ⅰ-Ⅱ trials. It is obvious that in the near future many different targeted therapies will be in use for treatment of AGC. In this review, the current status of targeted therapies in the treatment of AGC and gastroesophageal junction tumors, including HER(2-3) inhibitors, epidermal growth factor receptor inhibitors, tyrosine kinase inhibitors, antiangiogenic agents, c-MET inhibitors, mammalian target of rapamycin inhibitors, agents against other molecular pathways fibroblast growth factor, Claudins, insulin-like growth factor, heat shock proteins, and immunotherapy, will be discussed.

Hepatitis C virus reactivation in cancer patients in the era of targeted therapies

The purpose of this review is to summarize the evidence of hepatitis C reactivation in cancer patients in the era of targeted therapies. Targeted therapies are novel therapeutics frequently used in cancer patients. During treatment with targeted therapies, viral replication is one of the major problems that can occur. The PubMed database, ASCO, and ASCO Gastrointestinal Cancer Symposium abstracts were searched up until September 15, 2013 using the following search keywords: “targeted therapies, rituximab, alemtuzumab, brentuximab, hepatitis, hepatitis C reactivation, tyrosine kinase inhibitors, imatinib, mammalian target of rapamycin (mTOR) inhibitors, everolimus, anti-HER therapies, trastuzumab, pertuzumab, lapatinib, anti-epidermal growth factor receptor therapies, cetuximab, panitumumab, and ipilimumab”. Papers considered relevant for the aim of this review were selected by the authors. The data about rituximab-induced hepatic flare in hepatitis C virus (HCV) positive patients is controversial. However, there is the possibility of life-threatening hepatic flare that can develop after HCV ribonucleic acid (HCV-RNA) viral load increases. Routine follow-up of liver function tests should be advised. Especially in high-risk patients, such as those with baseline chronic active hepatitis and cirrhosis, and where there are plans to administer rituximab concomitantly with corticosteroids, it is advised to have close follow-up of HCV viral load. The data is insufficient to make accurate statements about the association of alemtuzumab therapy and HCV reactivation. However, alemtuzumab may cause deep immunosuppression. Due to this, it is better to follow up with liver function tests and HCV RNA levels during alemtuzumab therapy. Brentuximab has effects on antibody dependent cellular toxicity and may decrease humoral immunity. Thus, we believe that during brentuximab treatment of HCV infected patients, clinicians may encounter hepatitis C reactivation. There have been no reported cases of hepatitis C reactivation with imatinib therapy. However, there are many reports of hepatitis B reactivation with imatinib treatment. Based on the evidence of hepatitis B reactivation with imatinib and the effects of imatinib on immune system functions, we suggest that imatinib therapy might be a risk factor for HCV reactivation. Anti-human epidermal growth factor receptor 2 therapies are not associated with hepatic flare in HCV infected patients. Post-transplant studies reported that mTOR was safely administered to patients with active hepatitis C without causing hepatic flare. Cetuximab and panitumumab have not been associated with HCV reactivation. Two cases of HCV infected melanoma were safely treated with ipilimumab without any HCV reactivation or hepatic flare. Targeted therapies are a new and emerging area of oncology treatment modalities. While treating HCV infected cancer patients, clinicians should be mindful of the immunosuppressive properties of targeted therapies. Further randomized trials are needed to establish algorithms for this issue.

Is exon mutation analysis needed for adjuvant treatment of gastrointestinal stromal tumor?

Gastrointestinal stromal tumors(GISTs) are the most common soft tissue sarcoma of the gastrointestinal tract,resulting from an activating mutation of stem cell factor receptor(KIT),and an activating mutation of the homologous platelet-derived growth factor receptor alpha(PDGFRA) kinase.Most GISTs(90%-95%) are KIT-positive.About 5% of GISTs are truly negative for KIT expression.GISTs have been documented to resistant conventional chemotherapeutics.Due to the KIT activation that occurs in the majority of the cases,KIT inhibition is the primary treatment approach in the adjuvant treatment of metastatic GISTs.Imatinib mesylate is an oral agent that is a selective protein tyrosine kinase inhibitor of the KIT protein tyrosine kinase,and it has demonstrated clinical benefit and objective tumor responses in most GIST patients in phase Ⅱ and Ⅲ trials.The presence and the type of KIT or PDGFRA mutation are predictive of response to imatinib therapy in patients with advanced and metastatic disease.Molecular analysis in phaseⅠ-Ⅱ trials revealed significant differences in objective response,progression-free survival,and overall survival between GISTs with different kinase mutations.The aim of this letter is to touch on the need for exon mutation analysis for adjuvant treatment with imatinib in GIST patients.

Cytomegalovirus gastritis after rituximab treatment in a nonHodgkln's lymphoma patient

Rituximab is a chimeric monoclonal antibody against CD20 antigen expressed on most B cells and is used for the treatment of malignant lymphomas expressing the CD20 antigen. It temporarily eliminates normal B-lymphocytes without a substantial decrease in serum immunoglobulin levels. Recently, several serious viral infections have been reported in association with rituximab use. Cytomegalovirus （CMV） is one of the agents that may be a cause of morbidity and mortality in immunocompromised individuals. In the face of exogenous or endogenous causes of immunosuppression, cytomegalovirus can result in retinitis, colitis, pneumonitis, or encephalitis. Presented here is a case of a patient with non-Hodgkin＇s lymphoma （NHL） who developed gastritis and enterocolitis due to CMV infection after treatment with rituximab.