Medical imaging-based companion diagnostics for solid tumors

Heterogeneity within the solid tumor microenvironment contributes to a poor prognosis and limited therapeutic responses.Companion diagnostics(CDx),a clinical technique that gives doctors vital biomarker information to enhance patient outcomes through matching specific treatments to patients,is becoming more and more important.However,most current US Food and Drug Administration(FDA)-approved CDx tests have difficulty dynamically reflecting variations in biomarkers in the solid tumor microenvironment because they are used in vitro and ex vivo.Consequently,new medical imaging-based CDx tests have been widely used to detect interpatient and intrapatient tumor heterogeneity to assess the intratumoral distribution of specific biomarkers and microenvironment variables.They provide patient stratification for targeted therapies and the differentiation of patient populations that benefit from alternative treatments.This review provides an overview of the recent advances in medical imaging-based CDx for solid tumors and summarizes the various tumor microenvironment biomarkers utilized in imaging-based CDx.We believe that this review offers additional details and directions for promoting medical imaging-based CDx development.

Role of human epidermal growth factor receptor 2 in gastric cancer:Biological and pharmacological aspects

Amplification of the human epidermal growth factor receptor 2 (HER2) gene and overexpression of the HER2 protein is found in 15%-20% of patients with gastric and gastroesophageal junction cancer. The degree of HER2 overexpression and amplification varies with the location of the carcinoma, with higher expression in the gastroesophageal and proximal parts compared to the distal parts of the stomach. Further, HER2 overexpression and amplification also seems to be related to the Lauren histological classification, with higher levels found in the intestinal phenotype compared to the diffuse and mixed types. The prognostic properties of HER2 overexpression and amplification are still under debate, but a large number of studies seem to indicate that HER2 is a negative prognostic factor. The usefulness of HER2 targeted therapy in gastric cancer was demonstrated in the ToGA trial, where HER2-positive patients with advanced gastric and gastroesophageal junction adenocarcinoma were randomized to receive 5-FU/capecitabine and cisplatin, either alone or in combination with trastuzumab. A statically significant gain in overall survival was seen in patients who received the combined treatment of trastuzumab and chemotherapy. Patients with a strong overexpression of the HER2 protein (IHC3+) specifically benefited from the treatment, with a median overall survival of 17.9 mo. As a consequence of the positive results of the ToGA trial, patients with advanced gastric or gastroesophageal junction adenocarcinoma are now routinely tested for HER2. The ToGA trial must be characterized as a landmark in the treatment of gastric cancer and it has paved the way for a number of new HER2 targeted compounds such as pertuzumab, ado-trastuzumab emtansine, lapatinib, afatinib, and dacomitinib, which are currently undergoing phase II and III clinical testing. Overall, this review will discuss the current status of HER2 in gastric and gastroesophageal junction cancer and the future direction in relation to HER2 target therapy.