Gastrointestinal stromal tumors: chemotherapy and imatinib

F-FDG PET Imaging in the Evaluation of Treatment Response to New Chemotherapies beyond Imatinib for Patients with Gastrointestinal Stromal Tumors

Aim. (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) is a powerful tool for staging and defining "good responders" to chemotherapy in tumor setting. Gastrointestinal stromal tumors (GISTs) are sarcoma involving gastrointestinal tract and may require a chemotherapy including imatinib, a tyrosine kinase inhibitor agent. Some GIST patients become refractory to imatinib; therefore, other tyrosine kinase inhibitors or concomitant chemotherapy may be considered for treatment. The aim of this paper is to assess if (18)F-FDG PET imaging is a useful tool to evaluate treatment response to new chemotherapies beyond imatinib for GIST patients. Methods. We performed a review of the literature about the role of (18)F-FDG PET in the evaluation of treatment response to new chemotherapies beyond imatinib for GIST patients. Results and Conclusions. (18)F-FDG PET seems to be able to assess therapy response earlier than computed tomography (CT) imaging in imatinib refractory GIST patients treated with other agents. However, a dual modality PET-CT imaging is recommendable to achieve a better detection of all lesions.

Elevated expression of c-kit in small venous malformations of blue rubber bleb nevus syndrome

The blue rubber bleb nevus syndrome (BRBNS, syn. bean syndrome) is a rare disease characterized by multiple cutaneous and gastrointestinal venous malformations associated with severe bleeding. However, the underlying molecular mechanisms are unknown and no targeted therapeutic approach exists to date. Here we report the case of a 19-year-old male patient with severe BRBNS in whom we analyzed the expression of tyrosine kinases frequently involved in tumor development by immunohistochemistry (vascular endothelial growth factor receptor-2, stem cell growth factor receptor (c-kit), platelet-derived growth factor receptor-β, and stem cell tyrosine kinase-1). A prominent expression of c-kit was detectable in smaller blood vessels, which also showed a moderate expression of the proliferation marker MIB1. Surprisingly, other growth factor receptors stained negatively. We therefore conclude that pharmacological inhibition of the c-kit signaling pathway in cavernous hemangiomas by selective kinase inhibitors may offer options in the treatment of BRBNS patients.

Epidermal growth factor receptor blockade in combination with conventional chemotherapy inhibits soft tissue sarcoma cell growth in vitro and in vivo

PURPOSE

The epidermal growth factor receptor (EGFR) is highly expressed in many human soft tissue sarcomas (STS). However, EGFR blockade has not apparently been used for human STS therapy; therefore, we examined the in vitro and in vivo effects and the underlying mechanisms before considering EGFR blockade as a therapy for STS patients.

EXPERIMENTAL DESIGN

Human STS tissues and cell lines were used to study EGFR expression and activation. Western blot analysis was used to evaluate effects of EGFR activation on downstream signaling. Cell culture assays were used to assess the effect of EGF stimulation as well as EGFR blockade (using an EGFR tyrosine kinase inhibitor, Iressa; AstraZeneca) on STS cell growth, apoptosis, and chemosensitivity. An in vivo study (HT1080 human fibrosarcoma cell line in nude/nude mice: Iressa, doxorubicin, Iressa + doxorubicin, vehicle) was used to examine tumor growth; pEGFR, proliferating cell nuclear antigen, and terminal deoxyribonucleotide transferase-mediated nick-end labeling staining helped assess the effect of therapy in vivo on STS EGFR activation, proliferation, and apoptosis.

RESULTS

EGFR was expressed and activated in STS cell lines and tumors, probably due to ligand binding rather than EGFR mutation. Stimulation caused activation of AKT and mitogen-activated protein kinase pathways. EGFR blockade inhibited these effects and also caused increased apoptosis, a p53-independent G(0)-G(1) cell cycle arrest, and decreased cyclin D1 expression. In vivo, Iressa + doxorubicin had markedly synergistic anti-STS effects.

CONCLUSION

EGFR blockade combined with conventional chemotherapy results in anti-human STS activity in vitro and in vivo, suggesting the possibility that combining these synergistic treatments will improve anti-STS therapy.

Tumores gástricos estromales. Diagnóstico, pronóstico y tratamiento quirúrgico actual. Seguimiento de 18 pacientes tratados

INTRODUCTION

Gastrointestinal stromal tumors (GIST) are the most frequent mesenchymal tumors of the digestive tract and their growth is directed through the signaling of the KIT or PDFGRA genes. The objective of the present study was to describe a series of cases of GIST tumors located in the stomach.

PATIENTS AND METHODS

We performed a retrospective, descriptive study of 18 patients diagnosed with gastric GIST and treated by means of gastric resection between July 1996 and June 2004. There were 12 women and six men, with a mean age of 63 years (range 33-84). In all patients, diagnosis was performed with immunohistochemical markers, such as CD34 and CD117. Investigations included endoscopy, abdominal ultrasonography, abdominal computerized axial tomography and fine-needle aspiration biopsy.

RESULTS

The main symptoms were digestive hemorrhage with severe anemia in 10 patients and abdominal pain in seven. In two patients, the tumors were incidental findings during laparotomy. Four patients underwent emergency surgery and the remainder underwent elective surgery. In all patients, gastric resection of variable extension was performed, according to tumoral location. Multicentric tumors were found in two patients. All patients were CD117- and CD34-positive. There were few postoperative complications. One patient died from acute myocardial infarction (5.6%). The mean follow-up was 47.5 months (range, 12-106). One patent died due to spread of a pancreatic neoplasm and the remaining patients are alive and without tumoral recurrence (94.1%).

CONCLUSIONS

Initial symptoms consist of upper gastrointestinal hemorrhage and abdominal pain. Gastroscopy and imaging techniques lead to a suspected diagnosis, which can be confirmed by immunohistochemical studies, in which the "gold standard" is positivity for CD117; CD34 (+), vimentin (+), actin (-) and protein S-100 (-) are also used. Treatment consists of tumoral resection with negative margins.