Neoadjuvant, adjuvant and palliative treatment of gastrointestinal stromal tumours (GIST) with imatinib: a centre-based study of 17 patients

Liver resection for metastatic GIST tumor improves survival in the era of tyrosine kinase inhibitors: a systematic review and meta-analysis

INTRODUCTION

Survival for gastrointestinal stromal tumor (GIST) has been increasing over the years after the introduction of tyrosine kinase inhibitors. However, the role of metastasectomy for GIST is still controversial. Patients are currently treated with imatinib or sunitinib in case of imatinib failures as optimal medical therapy for metastatic GIST.

METHODS

The Pubmed, EMBASE, and Cochrane Library were systematically searched. Overall survival following liver resection ± tyrosine kinase inhibitor treatment for metastatic GIST was compared to treatment with tyrosine kinase inhibitors alone.

RESULTS

Eleven studies including both randomized control trials and retrospective cohort studies were included in the final analysis with a total of 988 patients. Seven studies encompassed data on 556 patients with isolated liver metastases (219 surgery ± drug groups and 337 drug-only groups) were included. Overall survival was significantly improved in patients undergoing liver resection ± drug therapy in comparison to drug therapy alone. [HR (95%CI) = 2.10 (1.58, 2.79); p<0.00001]. Subgroup analysis showed that patients also had improved progression free survival based on 4 studies. [HR (95%CI) = 1.92 (1.43, 2.56); p<0.00001]. In case of concurrent liver and peritoneal metastases, patients showed improved overall survival with aggressive surgical approaches based on 10 studies. [HR (95%CI) = 1.90 (1.56, 2.31); p<0.00001].

CONCLUSION

This meta-analysis found that liver resection for patients with metastatic GIST regardless of peritoneal metastases improved progression free and overall survival in conjunction with tyrosine kinase inhibitors as compared with medical therapy alone. Furthermore, liver resections did not have any immediate detrimental impact on survival in the group of patients selected.

Dataset for reporting of gastrointestinal stromal tumours: recommendations from the International Collaboration on Cancer Reporting (ICCR)

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract and are among the most frequent sarcomas. Accurate diagnosis, classification, and reporting are critical for prognostication and patient management, including selection of appropriate targeted therapy. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of GIST. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major international pathology and cancer organizations. An international expert panel consisting of pathologists, a surgical oncologist, and a medical oncologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were subspecialized soft tissue tumour experts and affiliated with tertiary referral centres. Commentary was provided for each data item to explain its clinical relevance and the rationale for selection as a core or noncore element. Following international public consultation, the datasets, which include synoptic reporting guides, were finalized and ratified, and published on the ICCR website. These first international datasets for GIST are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will ultimately help to improve the management of patients with GIST. All the ICCR datasets, including these on GIST, are freely available worldwide on the ICCR website (www.iccr-cancer.org/datasets).

A literature review and database of how the primary KIT/PDGFRA variant of a gastrointestinal stromal tumour predicts for sensitivity to imatinib

It is well recognized that the primary KIT or PDGFRA variant of a gastrointestinal stromal tumour (GIST) can predict sensitivity to imatinib. However, these data are currently spread across a wide range of publications and have not been collated as one reference. A broad-ranging literature search was therefore performed to assemble such a database which should help optimize imatinib-based management of GIST patients henceforth. Having excluded wild type GISTs and results for imatinib used as adjuvant therapy, 79 publications (dated August 2001 to March 2022) underwent data extraction. These data on imatinib sensitivity were either derived from in vitro studies, predicted by in silico analysis or based on in vivo clinical patient response. Data interpretation carried some caveats: there was a potential for replication of patient-derived data between older and new publications; only predicted protein sequences were presented; the criteria used to record clinical response were not uniform across all publications; and imatinib dosage could vary between different clinical publications. However, these data showed broad agreement of imatinib sensitivity amongst similar subtypes of KIT or PDGFRA variant. There was also agreement between in vivo versus in vitro/in silico derived sensitivity data for most variants when both data types were available.

Unresectable GIST liver metastases and liver transplantation: A review and theoretical basis for a new indication

BACKGROUND

Liver metastases from gastrointestinal stromal tumors (GIST) can be found synchronously to a primary tumor and in the medium/long term after resection of a high-risk GIST. In these cases, treatment with tyrosine kinase inhibitors like imatinib has provided good results, but drug resistance is common after two years of treatment. Liver resection of potentially resectable metastases can improve the results of medical treatment. In cases of unresectability, the role of liver transplantation (LT) has not been well-studied.

MATERIALS AND METHODS

A review of the literature was undertaken from January 1995 to December 2020 following the PRISMA and AMSTAR guidelines.

RESULTS

Fifteen cases were identified. In eight cases, the LT was carried out before 2002. Mutational status was only studied in seven cases. LT was performed in 12 cases with a deceased donor and in three cases with a living donor. After a mean follow-up of 52.4 months, overall survival was 86.6% with disease-free survival of 53.3% CONCLUSION: LT in the management of unresectable GIST metastases has rarely been performed. Although its application has a solid theoretical basis, its use understood as a radical extension of a standard resection can only be recommended within prospective studies by groups with considerable experience in both GIST and transplantation care.

Tumor necrosis is significantly associated with reduced recurrence-free survival after curative resection of gastrointestinal stromal tumors

BACKGROUND OBJECTIVES

The impact of tumor necrosis as a prognostic factor in gastrointestinal stromal tumor (GISTs) is still debated. The objective was to determine whether tumor necrosis is an independent risk factor for survival in patients with GISTs.

METHODS

Patients undergoing surgery for primary GIST from March 2003 to October 2018 at two sarcoma referral centers were retrospectively identified. Patients who received neoadjuvant imatinib were excluded. Multivariable Cox regression models were produced, to assess whether tumor necrosis was an independent predictor of either overall or recurrence-free survival.

RESULTS

Forty-one out of 195 (21.0%) patients had tumor necrosis. Tumor necrosis was associated with a significantly higher modified National Institute of Health risk score, with 29 out of 41 (70.7%) patients with necrosis classified as high risk, compared to 52 out of 153 (34.0%) without (p < .001). Tumor necrosis was found to be independently predictive of recurrence-free survival (hazard ratio: 5.26, 95% CI: 2.62-10.56, p < .001) on multivariable analysis. At 5 years, 44.3% of patients with necrosis had either died or developed recurrence, compared to 9.9% of those without.

CONCLUSION

Tumor necrosis is an independent predictor of recurrence-free survival in patients with operable GISTs. It should be routinely reported by pathologists, and used by clinicians when counseling patients and deciding on adjuvant therapy.

TUFM-knockdown inhibits the migration and proliferation of gastrointestinal stromal tumor cells

Gastrointestinal stromal tumors (GISTs) are the most common pathologic type of mesenchymal tumor in the digestive tract. Patients with GIST face the risk of metastasis, postoperative recurrence and imatinib mesylate (IM) resistance. Mitochondrial Tu translation elongation factor (TUFM) is highly expressed in GISTs, and is associated with oncogenesis, progression and prognosis. There is evidence that TUFM is involved in tumor invasion and metastasis. However, the effect of TUFM on GIST-T1 cells and the IM-resistant GIST-IR cell line remains unclear. The present study aimed to evaluate the effects of TUFM on the proliferation, migration and apoptosis of GIST cells in vitro. TUFM short hairpin (sh)RNA expression plasmids were transfected into GIST-T1 and GIST-IR cells by electroporation. The expression levels of enhanced green fluorescent protein were observed by fluorescence microscopy to evaluate the electroporation efficiency. The expression levels of TUFM were detected by western blot analysis and reverse transcription-quantitative PCR. Cell proliferation was assessed by counting cells and using a Cell Counting Kit-8 assay. Cell migration was analyzed using wound healing and Transwell migration assays. Cell cycle distribution and late apoptosis were assessed by flow cytometry. TUFM shRNA expression plasmids were successfully transfected into the GIST cell line by electroporation. The transfection efficiency was >75%, and the TUFM gene silencing efficiency was 73.2±1.4%. TUFM-knockdown decreased the proliferation and migration capacity of GIST-T1 and GIST-IR cells. The proportion of cells in the pre-G1 stage was increased without change in the proportions of cells in the G₁, S and G₂/M stages after TUFM silencing in GIST-T1 and GIST-IR cells. TUFM may be related to GIST infiltration and metastatic recurrence, suggesting that TUFM may be an effective target for preventing the progression and metastasis of GISTs.

Characterization of an Unusual Mesenchymal Tumor in the Proventriculus of a Free-ranging Red-tailed Hawk (Buteo jamaicensis)

An adult, female red-tailed hawk (Buteo jamaicensis) was presented for examination after being found unable to fly on a private citizen's property. Further diagnostic testing revealed a vascular, soft tissue mass arising from the serosal surface of the proximal proventriculus. Postmortem histological and immunohistochemical examination of the mass revealed an unusual mesenchymal tumor with features consistent with a leiomyoma or low-grade gastrointestinal stromal tumor.

Enormous gastrointestinal stromal tumor arising from the stomach causing weight loss and anemia in an elderly female: Case report

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Gastrointestinal stromal tumors are the most common mesenchymal tumors of gastrointestinal tract.

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Surgical excision with normal safety margins is the main form of treatment.

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Preoperative imatinib therapy is used in unresectable or recurrent tumors.

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Huge tumors may not respond to medical therapy.

Introduction

Gastrointestinal stromal tumors are the most common mesenchymal tumors of gastrointestinal tract originating from the interstitial cell of Cajal. The presentation is variable depending on the size and site. CT scan is the most widely used imaging. The primary treatment is surgical resection. Imatinib may be used in unresectable tumors or preoperatively.

Case presentation

A 65-year-old lady had weight loss and repeated vomiting for one year. Examination showed a non-tender mass in the left hypochonrdium arising below the costal margin extending to 15 cm toward the left iliac fossa. It was firm with smooth surface. CT-scan examination showed a 45 cm × 21 cm mass arising between the spleen and the left kidney and displacing the kidney toward the midline. Gastroscopy and biopsy showed gastrointestinal stromal tumor. During surgery an enormous gastric tumor attached to the spleen. Total gastrectomy en-block with splenectomy and reconstruction done through roux-en-y esophago-jejunostomy and jejunojejunostomy.

Conclusion

GISTs most commonly affect the stomach, most tumors are treated by primary surgical excision with normal safety margins, advanced disease may need imatinib before surgery which helps in decreasing the size of the tumor and makes surgery easier.

Gastrointestinal stromal tumours: advances in surgical and pharmacological management options

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasm of the gastrointestinal tract. The stomach is most commonly affected. Advances in immunopathology have identified a mutation in the c-KIT proto-oncogene, leading to the development of the tyrosine-kinase inhibitor Imatinib as targeted therapy for advanced disease. Surgery, however, remains the only curative treatment of resectable primary GIST. This review article aims at reviewing the management of primary GISTs, investigating recurrences, exploring the role of surgery in metastatic disease and looking into combined surgery and molecular therapy for GISTs.

Combined Therapy of Gastrointestinal Stromal Tumors

Radical surgery is the mainstay of therapy for primary resectable, localized gastrointestinal stromal tumors (GIST). Nevertheless, approximately 40% to 50% of patients with potentially curative resections develop recurrent or metastatic disease. The introduction of imatinib mesylate has revolutionized the therapy of advanced (inoperable and/or metastatic) GIST and has become the standard of care in treatment of patients with advanced GIST. This article discusses the proper selection of candidates for adjuvant and neoadjuvant treatment in locally advanced GIST, exploring the available evidence behind the combination of preoperative imatinib and surgery.

Asian Consensus Guidelines for the Diagnosis and Management of Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors originating in the gastrointestinal tract. With the introduction of molecular-targeted therapy for GISTs which has yielded remarkable outcomes, these tumors have become a model of multidisciplinary oncological treatment. Although Western clinical guidelines are available for GISTs, such as those published by the National Comprehensive Cancer Network (NCCN) and the European Society of Medical Oncology (ESMO), the clinical situations in Asian countries are different from those in Western countries in terms of diagnostic methods, surgical approach, and availability of new targeted agents. Accordingly, we have reviewed current versions of several GIST guidelines published by Asian countries (Japan, Korea, China, and Taiwan) and the NCCN and ESMO and discussed the areas of dissensus. We here present the first version of the Asian GIST consensus guidelines that were prepared through a series of meetings involving multidisciplinary experts in the four countries. These guidelines provide an optimal approach to the diagnosis and management of GIST patients in Asian countries.

Surgical management of advanced gastrointestinal stromal tumors: an international multi-institutional analysis of 158 patients

BACKGROUND

Patients with advanced gastrointestinal stromal tumors (GIST) are at high risk for recurrence after surgery. The aim of this study was to characterize outcomes of advanced GIST treated with surgery from a large multi-institutional database in the tyrosine kinase inhibitor (TKI) era.

STUDY DESIGN

Patients who underwent surgery for an advanced GIST from 1998 through 2012 were identified. Demographic, clinicopathologic, perioperative, and survival data were collected and analyzed.

RESULTS

There were 87 patients with locally advanced GIST and 71 patients with recurrent/metastatic GIST. The vast majority (95%) of patients with locally advanced GIST required a multivisceral resection; most patients (87%) underwent a microscopically complete (R0) resection. Although 82% of patients had high-risk tumors according to modified NIH criteria or had recurrent/metastatic disease, only 56% of patients received adjuvant TKI therapy. Among patients with locally advanced GIST, 3-year recurrence-free survival and overall survival rates were 65% and 87%, respectively. In contrast, 3-year recurrence-free survival and overall survival rates among patients with recurrent/metastatic GIST were 49% and 82%, respectively. On multivariate analysis, predictors of worse outcomes included high mitotic rate and male sex for patients with locally advanced GIST, and age and lack of adjuvant TKI therapy were associated with adverse outcomes among patients with recurrent/metastatic GIST (all p < 0.05).

CONCLUSIONS

Resection of advanced GIST can be safely accomplished with high rates of R0 resection. Among patients with advanced GIST, TKI therapy was underused. Barriers to the use of TKI therapy in this population should be explored.

Is there a role of surgery in patients with recurrent or metastatic gastrointestinal stromal tumours responding to imatinib: a prospective randomised trial in China

OBJECTIVES

For advanced gastrointestinal stromal tumour (GIST) patients who are responding to imatinib mesylate, the role of surgery has not been formally demonstrated. This multicenter randomised controlled trial was designed to assess whether surgery to treat residual disease for patients with recurrent/metastatic GISTs responding to imatinib mesylate (IM) improved progression free survival (PFS) compared with IM treatment alone.

METHODS

Between 3 and 12months after starting IM for recurrent/metastatic GISTs, eligible patients were randomised to two arms: Arm A (surgery for residual disease) and Arm B (IM treatment alone). In Arm A (19pts), surgery was performed to remove residual macroscopic lesions as completely as possible, and IM treatment continued after surgery. In Arm B (22pts), IM was given alone at a dose of 400mg per day until disease progression. The primary end-point was PFS measured from the date IM started. This study was registered in the ChiCTR registry with the ID number ChiCTR-TRC-00000244.

RESULTS

This randomised trial was closed early due to poor accrual. Only 41 patients were enrolled as opposed to 210 patients planned. 2-year PFS was 88.4% in the surgery arm and 57.7% in the IM-alone arm (P=0.089). Median overall survival (mOS) was not reached in the surgery arm and 49months in patients with IM-alone arm (P=0.024).

CONCLUSIONS

While no significant differences were observed in the two arms, this study suggests that surgical removal of the metastatic lesion may improve the outcome of advanced GIST patients and should stimulate additional research on this topic.

Rare cystic liver lesions: A diagnostic and managing challenge

Cystic formations within the liver are a frequent finding among populations. Besides the common cystic lesions, like simple liver cysts, rare cystic liver lesions like cystadenocarcinoma should also be considered in the differential diagnosis. Thorough knowledge of each entity’s nature and course are key elements to successful treatment. Detailed search in PubMed, Cochrane Database, and international published literature regarding rare cystic liver lesions was carried out. In our research are included not only primary rare lesions like cystadenoma, hydatid cyst, and polycystic liver disease, but also secondary ones like metastasis from gastrointestinal stromal tumors lesions. Up-to date knowledge regarding diagnosis and management of rare cystic liver lesions is provided. A diagnostic and therapeutic algorithm is also proposed. The need for a multidisciplinary approach by a team including radiologists and surgeons familiar with liver cystic entities, diagnostic tools, and treatment modalities is stressed. Patients with cystic liver lesions must be carefully evaluated by a multidisciplinary team, in order to receive the most appropriate treatment, since many cystic liver lesions have a malignant potential and evolution.

Neoadjuvant imatinib in locally advanced gastrointestinal stromal tumors (GIST): the EORTC STBSG experience

BACKGROUND

Preoperative imatinib therapy of locally advanced GIST may facilitate resection and decrease morbidity of the procedure.

METHODS

We have pooled databases from 10 EORTC STBSG sarcoma centers and analyzed disease-free survival (DFS) and disease-specific survival (DSS) in 161 patients with locally advanced, nonmetastatic GISTs who received neoadjuvant imatinib. OS was calculated from start of imatinib therapy for locally advanced disease until death or last follow-up (FU) after resection of the GIST. DFS was calculated from date of resection to date of disease recurrence or last FU. Median FU time was 46 months.

RESULTS

The primary tumor was located in the stomach (55%), followed by rectum (20%), duodenum (10%), ileum/jejunum/other (11%), and esophagus (3%). The tumor resection after preoperative imatinib (median time on therapy, 40 weeks) was R0 in 83%. Only two patients have demonstrated disease progression during neoadjuvant therapy. Five-year DSS/DFS rates were 95/65%, respectively, median OS was 104 months, and median DFS was not reached. There were 56% of patients who continued imatinib after resection. Thirty-seven GIST recurrences were diagnosed (only 5 local relapses). The most common mutations affected exon 11 KIT (65%). Poorer DFS was related to primary tumor location in small bowel and lack of postoperative therapy with imatinib.

CONCLUSIONS

Our analysis comprising the largest group of GIST patients treated with neoadjuvant imatinib in routine practice indicates excellent long-term results of combined therapy in locally advanced GISTs.

Gastrointestinal stromal tumors (GISTs) express somatostatin receptors and bind radiolabeled somatostatin analogs

BACKGROUND

Gastrointestinal stromal tumors (GISTs) can be effectively treated with tyrosine kinase inhibitors (TKIs). However, some patients with GIST develop drug resistance, and alternative treatment strategies are therefore needed. The aim of this study was to analyze the expression of somatostatin receptors (SSTR) in GIST as a target for peptide receptor-mediated radiotherapy (PRRT).

MATERIAL AND METHODS

Expression profiling of SSTR1-5 was performed on biopsies from 34 GISTs (16 gastric tumors, 15 small intestinal tumors, and three rectal tumors). SSTR scintigraphy ((111)In-octreotide) and measurement of (111)In activity in tumor specimens was performed in seven patients. Uptake and internalization of (177)Lu- octreotate was studied in primary cell cultures from two patients.

RESULTS

Quantitative PCR analysis showed expression of SSTR1 and SSTR2 in the majority of tumors, while SSTR3-5 were expressed at low levels. Immunohistochemical analysis confirmed the presence of SSTR1 and SSTR2 proteins in all GISTs, and SSTR3-5 in a subset of tumors. Diagnostic imaging by SSTR scintigraphy, using (111)In-octreotide, demonstrated tumor uptake of (111)In in three of six GIST patients. Measurement of (111)In activity in excised tumor specimens from five patients gave tumor-to-blood (T/B) activity ratios of between eight and 96. Tumor cells in primary culture (gastric and small intestinal GIST) specifically bound and internalized (177)Lu when incubated with the therapeutic compound (177)Lu-octreotate for 4-48 hours (p < 0.05).

CONCLUSION

Peptide receptor-mediated radiotherapy via SSTR may provide a novel treatment strategy in carefully selected GIST patients with TKI-resistant tumors.

Fool's gold, lost treasures, and the randomized clinical trial

Background

Randomized controlled trials with a survival endpoint are the gold standard for clinical research, but have failed to achieve cures for most advanced malignancies. The high costs of randomized clinical trials slow progress (thereby causing avoidable loss of life) and increase health care costs.

Discussion

A malignancy may be caused by several different mutations. Therapies effective vs one mutation may be discarded due to lack of statistical significance across the entire population. Conversely, expensive large randomized trials may have sufficient statistical power to demonstrate benefit despite the therapy only working in subgroups. Non-cost-effective therapy is then applied to all patients (including subgroups it cannot help). Randomized trials comparing therapies with different mechanisms of action are misleading since they may conclude the therapies are “equivalent” despite benefitting different subpopulations, or may erroneously conclude that one therapy is superior simply because it targets a larger subpopulation. Furthermore, minor variances in patient selection may determine study outcome, a therapy may be discarded as ineffective despite substantial benefit in one subpopulation if harmful in another, randomized trials may more effectively detect therapies with minor benefit in most patients vs marked benefit in subpopulations, and randomized trials in unselected patients may erroneously conclude that “shot-gun” combinations are superior to single agents when sequential administration of personalized single agents might work better and spare patients treatment with drugs that cannot help them. We must identify predictive biomarkers early by comparing responding to progressing patients in phase I-II trials. Enriching randomized trials for biomarker-positive patients can markedly reduce required patient numbers and costs despite expensive screening for biomarker-positive patients. Available data support approval of new drugs without randomized trials if they yield single-agent sustained responses in patients refractory to standard therapies. Conversely, new approaches are needed to guide development of drug combinations since both standard phase II approaches and phase II-III randomized trials have a high risk of misleading.

Summary

Traditional randomized clinical trials approaches are often inefficient, wasteful, and unreliable. New clinical research paradigms are needed. The primary outcome of clinical research should be “Who (if anyone) benefits?” rather than “Does the overall group benefit?”

Gastrointestinal stromal tumor--background, pathology, treatment

Gastrointestinal stromal tumor (GIST) represents the most common mesechymal tumor of the gastrointestinal tract. Discovery of the relationship between unregulated KIT kinase and GIST transformation has led to diagnostic and therapeutic targeting. Imatinib is the recommended first-line treatment of metastatic GIST. In addition, the combination of surgery and imatinib for primary GIST is indicated in the adjuvant setting of high-risk patients and there may be benefit for this combination in the neoadjuvant setting. The success of molecular targeted therapy in GIST represents an important and exciting advance in solid tumor oncology.

Treatment response monitoring in patients with gastrointestinal stromal tumor using diffusion-weighted imaging: preliminary results in comparison with positron emission tomography/computed tomography

We compared the parameters derived from diffusion-weighted imaging (DWI) and positron emission tomography/computed tomography (PET/CT) for treatment response evaluation and response prediction in patients with gastrointestinal stromal tumor (GIST). Seven patients with histologically proven metastatic disease were enrolled. DWI and PET/CT data were collected from all patients at diagnosis and from six at follow-up. All 37 lesions were identifiable in DWI with a sensitivity of 100%. To achieve higher accuracy, we used the apparent diffusion coefficient (ADC) of liver and background noise as thresholds for the measurement of the ADCs of lesions. Significant inverse correlations were found between ADC(mean_thr) (ADC(mean) with thresholds) and SUV(mean) (mean standardized uptake value) (R(2)=0.523, p<0.001 at diagnosis, and R(2)=0.916, p<0.001 at follow-up), between ADC(mean_thr) and SUV(max) (maximum SUV) (R(2)=0.529, p<0.001 at diagnosis, and R(2)=0.761, p<0.001 at follow-up), between ΔADC(mean_thr) (percentage change in ADC(mean_thr) ) and ΔSUV(mean) (percentage change in SUV(mean) ) (R(2)=0.384, p<0.001), and between ΔADC(mean_thr) and ΔSUV(max) (percentage change in SUV(max) ) (R(2)=0.500, p<0.001). In lesion-based analysis, pre-treatment ADC(mean_thr) outperformed SUV(mean) and SUV(max) in treatment response prediction, with an area under the receiver operating characteristic curve of 0.706. These results show that DWI can provide a quantitative assessment comparable with PET/CT in GIST lesion characterization, treatment response evaluation and response prediction.

KIT (CD117) expression in a subset of non-small cell lung carcinoma (NSCLC) patients

We have previously described the expression of CD44, CD90, CD117 and CD133 in NSCLC tumors, adjacent normal lung, and malignant pleural effusions (MPE). Here we describe the unique subset of tumors expressing CD117 (KIT), a potential therapeutic target. Tumor and adjacent tissue were collected from 58 patients. Six MPE were obtained before therapy. Tissue was paraffin embedded for immunofluorescent microscopy, disaggregated and stained for flow cytometry or cryopreserved for later culture. The effect of imatinib on CD117(high)/KIT+ tumors was determined on first passage cells; absolute cell counts and flow cytometry were readouts for drug sensitivity of cell subsets. Primary tumors divided into KIT(neg) and KIT+ by immunofluorescence. By more sensitive flow cytometric analysis, CD117+ cytokeratin+ cells were detected in all tissues (1.1% of cytokeratin+ cells in normal lung, 1.29% in KIT "negative" tumors, 40.7% in KIT+ tumors, and 0.4% in MPE). In KIT+/CD117(high), but not KIT+/CD117(low) tumors, CD117 was overexpressed 3.1-fold compared to normal lung. Primary cultures of CD117(high) tumors were sensitive to imatinib (5 µM) in short term culture. We conclude that NSCLC tumors divide into CD117(low) and CD117(high). Overexpression of CD117 in CD117(high) NSCLC supports exploring KIT as a therapeutic target in this subset of patients.

Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

Despite their rarity in incidence and prevalence, gastrointestinal stromal tumors (GISTs) have emerged as a distinct and noteworthy pathogenetic entity. The clinical management of GISTs has rapidly evolved due to the recent elucidation of their oncogenic signal transduction pathway and the introduction of molecular-targeted therapies. Successful management of GISTs requires a multidisciplinary approach firmly based on an accurate histopathologic diagnosis. In 2007, the Korean GIST study group published the first guideline for optimal diagnosis and treatment of GISTs in Korea. The second version of the guideline was published in 2010. Herein, we provide the results of relevant clinical studies for the purpose of further revision to the guideline. We expect this new guideline will enhance the accuracy of diagnosis, as performed by members of the Korean associate of physicians involved in GIST patient care, thus improving the efficacy of treatment.

Updates on the management of gastrointestinal stromal tumors

Despite being the most common sarcoma of the gastrointestinal tract, gastrointestinal stromal tumor (GIST) has been widely recognized as a unique entity for just over a decade. The advent of tyrosine kinase inhibitors has revolutionized the diagnosis and treatment of GIST. Although surgery remains the only chance for cure, multimodal treatment that includes molecular therapy continues to develop. Optimal management of GIST requires careful radiographic, pathologic, medical, and surgical care, emphasizing the need for a multidisciplinary approach. This review highlights recent developments in the management of GIST.

Small intestine gastrointestinal stromal tumors

PURPOSE OF REVIEW

To review the contemporary management of gastrointestinal stromal tumor (GIST), including endoscopy, surgery, and systemic therapy, highlighting the aspects unique to small intestinal tumors.

RECENT FINDINGS

Tumor size, mitotic count, and site of origin are the three key prognostic factors, with mitotic count being the single strongest predictor of recurrence. Tumors arising in the small bowel have worse prognosis than those of comparable size and mitotic count arising in other organs. Endoscopy and endoscopic ultrasound-guided, fine-needle aspiration are key components in the diagnosis of GIST. The role of endoscopy in surveillance and resection remain investigational. Surgery, either open or laparoscopic, remains the only curative option, but recurrence rates are high. Adjuvant therapy with imatinib mesylate improves recurrence-free survival rates and may improve overall survival (OS) with longer duration of treatment. Neoadjuvant imatinib may play an important role in the management of patients with locally advanced disease. For patients with advanced disease, first-line imatinib and second-line sunitinib malate have improved progression-free and OS rates. Systemic treatment should be continued life-long or until treatment failure.

SUMMARY

Advances in the last decade have dramatically changed the management and prognosis of patients with primary and advanced GIST.

Adjuvant and neoadjuvant imatinib therapy: current role in the management of gastrointestinal stromal tumors

Although surgery remains the mainstay for the treatment of primary gastrointestinal stromal tumors (GIST), a significant number of patients experience disease recurrence within 5 years of surgery. The emergence of imatinib therapy for the treatment of patients with advanced GIST has offered unprecedented improvements in clinical outcomes for these patients. Prospective clinical trials have supported the efficacy and safety of imatinib before and after surgical resection of GIST. The American College of Surgeons Oncology Group Z9001 pivotal trial revealed that 1 year of adjuvant imatinib therapy provides significantly superior recurrence-free survival in patients with GIST after surgical resection, when compared to placebo. Additional trials and case studies have also begun to define the potential clinical benefit of imatinib in the neoadjuvant setting. Optimized risk stratification paradigms will be required to ensure the appropriate selection of patients to undergo treatment with imatinib in these settings. Risk stratification schemes are evolving that potentially will include mutation status and tumor rupture, and predictive nomograms have recently been proposed. The recent European Society of Medical Oncology and National Comprehensive Cancer Network guidelines mention use of adjuvant imatinib for ≥ 1 year in patients with KIT(+) , resectable GIST at high risk of recurrence. Moreover, the guidelines support the use of neoadjuvant imatinib in cases of limited disease if it would facilitate less extensive surgery and organ sparing. This article reviews pivotal efficacy and safety data for adjuvant imatinib and explores the potential clinical benefit of neoadjuvant imatinib in patients with GIST.

Efficacy of imatinib mesylate neoadjuvant treatment for a locally advanced rectal gastrointestinal stromal tumor

Surgery is the standard treatment for a primary gastrointestinal stromal tumor (GIST); however, surgical resection is often not curative, particularly for large GISTs. In the past decade, with imatinib mesylate (IM), management strategies for GISTs have evolved significantly, and now IM is the standard care for patients with locally advanced, recurrent or metastatic GISTs. Adjuvant therapy with imatinib was recently approved for use, and preoperative imatinib is an emerging treatment option for patients who require cytoreductive therapy. IM neoadjuvant therapy for primary GISTs has been reported, but there is no consensus on the dose of the drug, the duration of treatment and the optimal time of surgery. These are critical because drug resistance or tumor progression can develop with a prolonged treatment. This report describes two cases of large rectal malignant GISTs, for which a abdominoperineal resection was initially anticipated. The two patients received IM preoperative treatment; we followed-up with CT or magnetic resonance imaging to access the response. After 9 months of treatment, a multi-disciplinary consensus that maximal benefit from imatinib had been achieved was reached. We determined the best time for surgical intervention and successfully performed sphincter-preserving surgery before resistance to imatinib or tumor progression occurred. We believe that a multidisciplinary team approach, considerating the optimal duration of therapy and the timing of surgery, is required to optimize treatment outcome.

Gastrointestinal stromal tumours--an update for histopathologists

This review aims to summarize recent knowledge gained about gastrointestinal stromal tumour (GIST) of particular relevance to histopathologists. KIT and PDGFRA mutation analyses can be useful for confirming a diagnosis of GIST, but there are some diagnostic limitations to these analyses, and so immunohistochemical markers currently remain crucial to the diagnostic process. Of these markers, CD117 and Discovered on GIST 1 (DOG1) are currently the most sensitive and specific markers of GIST, and recent data appear to disprove the fear that antigen retrieval causes false-positive CD117 immunostaining. The accurate prognostication of GIST has been greatly helped by the National Institutes of Health (NIH) and Armed Forces Institute of Pathology (AFIP) classification systems, although both systems still have limitations, and the behaviours of certain GIST subgroups are less well predicted by both systems. KIT and PDGFRA mutation analyses can help to predict the response of GISTs to receptor tyrosine kinase inhibitors, and both GISTs that respond and those that show resistance to these inhibitors may show characteristic pathological changes. Some GIST subgroups (e.g. Carney syndrome and paediatric GISTs) have had recently described clinicopathological and/or molecular characteristics which may help with the diagnosis and/or treatment of these specific neoplasms.

Imatinib as adjuvant therapy for gastrointestinal stromal tumors: a systematic review

The high risk of recurrence in resected gastrointestinal stromal tumor (GIST) highlights the need for effective adjuvant treatment. This review evaluates the clinical efficacy and safety of imatinib for adjuvant treatment of localized KIT (CD117)-positive resected GIST. Relevant studies were identified by searching several electronic databases from inception to August 2009. Searches were supplemented by examining bibliographies of included studies, searching conference proceedings and consulting experts. All study types were included. Methodological quality was assessed using published criteria. Sixteen studies met the eligibility criteria, comprising one randomized controlled trial (RCT), three phase II studies, three cohort studies and nine case reports. In the RCT, the estimated 1-year recurrence-free survival was 98% [95% confidence interval (CI), 96-100] in the imatinib group versus 83% (95% CI, 78-88) in the placebo group, corresponding to a 65% reduction in the risk of disease recurrence (hazard ratio, 0.35; 95% CI, 0.22-0.53; p < 0.0001) with an absolute recurrence-free survival difference of 15% at 1 year. Other nonrandomized studies reported similar outcomes demonstrating that imatinib used in the adjuvant setting improved recurrence-free survival. The optimum duration of adjuvant treatment, safety and efficacy is currently under investigation with two ongoing RCTs (EORTC 62024 and SSG XV111) and two nonrandomized studies (NCT00867113 and NCT00171977). This study adds to the evidence (based on one RCT and a number of observational studies) that GIST patients treated with adjuvant imatinib therapy show an improvement in recurrence-free survival compared to placebo or no treatment after resection of KIT-positive localized GIST with tolerable toxicity.

Downsizing treatment with tyrosine kinase inhibitors in patients with advanced gastrointestinal stromal tumors improved resectability

BACKGROUND

Gastrointestinal stromal tumors (GISTs) express the receptor tyrosine kinase KIT. Most GISTs have mutations in the KIT or PDGFRA gene, causing activation of tyrosine kinase. Imatinib, a tyrosine kinase inhibitor (TKI), is the first-line palliative treatment for advanced GISTs. Sunitinib was introduced for patients with mutations not responsive to imatinib. The aim was to compare the survival of patients with high-risk resected GISTs treated with TKI prior to surgery with historical controls and to determine if organ-preserving surgery was facilitated.

METHODS

Ten high-risk GIST-patients had downsizing/adjuvant TKI treatment: nine with imatinib and one with sunitinib. The patients were matched with historical controls (n = 89) treated with surgery alone, from our population-based series (n = 259). Mutational analysis of KIT and PDGFRA was performed in all cases. The progression-free survival was calculated.

RESULTS

The primary tumors decreased in mean diameter from 20.4 cm to 10.5 cm on downsizing imatinib. Four patients with R0 resection and a period of adjuvant imatinib had no recurrences versus 67% in the historical control group. Four patients with residual liver metastases have stable disease on continuous imatinib treatment after surgery. One patient has undergone reoperation with liver resection. The downsizing treatment led to organ-preserving surgery in nine patients and improved preoperative nutritional status in one patient.

CONCLUSIONS

Downsizing TKI is recommended for patients with bulky tumors with invasion of adjacent organs. Sunitinib can be used for patients in case of imatinib resistance (e.g., wild-type GISTs), underlining the importance of mutational analysis for optimal surgical planning.

Gastrointestinal stromal tumors (GISTs): an updated experience

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are relatively common mesenchymal tumors of the digestive tract characterized by c-KIT mutations. This is a comprehensive review of the current data of the literature on the various aspects of the diagnosis and treatment of these tumors.

METHODS

The stomach is the most commonly involved site for these tumors in the digestive tract. Computed tomography and endoscopy can usually establish the diagnosis. The study of certain specific immunohistochemical markers may contribute to better characterization of these tumors.

RESULTS

Surgical resection of GISTs has been the most effective therapy. In addition, targeted therapy with tyrosine kinase inhibitors may reduce the development of recurrence or decrease the disease progression in patients with metastatic disease.

CONCLUSIONS

The introduction of tyrosine kinase inhibitors has resulted in significant improvement in the overall prognosis of these patients. Furthermore, preoperative imatinib can decrease tumor volume and is associated with complete surgical resection in locally advanced primary GISTs.

[Successful resection of locally advanced gastrointestinal stromal tumor of the ampulla of Vater after treatment with imatinib]

Gastrointestinal stromal tumor (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract arising from Cajal's cells, expressing CD 117. The standard treatment for primary GIST is complete surgical resection. Imatinib mesylate, a specific tyrosine kinase inhibitor, is effective against locally advanced and metastatic GIST. There are several reports of the effect of preoperative imatinib in patients with unresectable and locally advanced primary GIST. We report a case of unresectable primary GIST of the ampulla of Vater, which we were able to completely resect after treatment with a dosage of imatinib 400 mg daily for 5 months. Twelve months later, the patient was treated with imatinib and doing well with no evidence of recurrence.

Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

Despite the rarity in incidence and prevalence, gastrointestinal stromal tumor (GIST) has emerged as a distinct pathogenetic entity. And the clinical management of GIST has been evolving very rapidly due to the recent recognition of its oncogenic signal transduction pathway and the introduction of new molecular-targeted therapy. Successful management of GIST requires a multidisciplinary approach firmly based on accurate histopathologic diagnosis. However, there was no standardized guideline for the management of Korean GIST patients. In 2007, the Korean GIST study group (KGSG) published the first guideline for optimal diagnosis and treatment of GIST in Korea. As the second version of the guideline, we herein have updated recent clinical recommendations and reflected changes in diagnosis, surgical and medical treatments for more optimal clinical practice for GIST in Korea. We hope the guideline can be of help in enhancing the quality of diagnosis by members of the Korean associate of physicians involving in GIST patients's care and subsequently in achieving optimal efficacy of treatment.

Neoadjuvant and adjuvant imatinib treatment in gastrointestinal stromal tumor: current status and recent developments

PURPOSE OF REVIEW

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract and is a paradigm of targeted therapy for solid tumors. Elucidation of the biology of GIST enabled use of imatinib, which revolutionized the prognosis of advanced GIST. Whereas surgical resection continues to be the standard of care for primary GIST, judicious and individualized use of adjuvant and neoadjuvant imatinib may enhance the potential for cure in select patients.

RECENT FINDINGS

Prospective trials utilizing adjuvant and neoadjuvant imatinib have established the safety and efficacy of these modalities adjunct to surgical resection. Correlative tissue studies derived from these trials have examined gene expression patterns, metabolic and radiographic response, and apoptosis during the first few days of imatinib therapy. As appropriate use of adjuvant and neoadjuvant imatinib requires proper patient selection, development of a predictive nomogram, and advances in mutational analysis represent progress toward individualized care.

SUMMARY

Imatinib is well tolerated and beneficial as adjuvant and neoadjuvant therapy, but its utility in these settings continues to be refined. The greatest benefit will derive from an individualized approach that considers multiple patient, drug, and tumor characteristics to assess risk and likelihood of benefit for each patient.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Role of surgery combined with kinase inhibition in the management of gastrointestinal stromal tumor (GIST)

BACKGROUND

Surgery is the standard treatment for primary, gastrointestinal stromal tumor (GIST); however, surgical resection often is not curative, particularly in large GIST. Five years after complete removal of their tumor, approximately half of treated patients relapse. Imatinib, an oral tyrosine kinase inhibitor (TKI), is first-line treatment in patients with metastatic or unresectable GIST. It has resulted in durable objective responses or stable disease in 84% of patients and is well tolerated. The efficacy of imatinib in advanced GIST has created interest in a variety of potential multimodal approaches to management that combine surgery with systemic therapy.

RESULTS

Recently, a large, randomized, Phase III, US cooperative group trial that compared adjuvant imatinib, for 1 year after primary complete surgical resection, with placebo in primary GIST, reported a significantly shorter time to relapse for those in the placebo group. This led to the approval of imatinib for this new indication in the US and Europe. Several studies evaluating the efficacy of adjuvant imatinib in patients with primary GIST who are at high risk for postoperative relapse are ongoing; in particular two large European studies are expected to yield preliminary results in the near future. Neoadjuvant therapy with imatinib is also being investigated for its effect on surgical outcomes, with first trial results reported.

CONCLUSION

This article provides an update on the rapidly evolving role of surgery, treatment with TKI therapy, and their combination in the management of GIST as well as further reviews pertinent to current clinical research findings.

NCCN Task Force report: update on the management of patients with gastrointestinal stromal tumors

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

[Aspects of surgical treatment for gastro-intestinal stromal tumors]

Gastro-intestinal stromal tumors (GIST) form the commonest subgroup of soft tissue sarcomas. They arise in the muscular layer of the esophagus, stomach, small intestines and rectum. Characteristic and important for the assessment of the extent of tumors is the peripheral rim vascularization of primary tumors and metastases. Indications for resection are given for tumors larger than 2 cm in size. Locally advanced GISTs can be advantageously treated with imatinib/sunitinib as neoadjuvant and it is often possible to select a low level of resection for this size of tumor and when the rim area is not hypervascularized. Even in the metastasizing stage surgical treatment can be used for elimination of resistant metastases or for removal of residual tumor tissue in an attempt to counteract secondary tumor progression. The effect of this treatment is currently being tested in a randomized phase III study.

Evaluation of sorafenib treatment in metastatic renal cell carcinoma with 2-fluoro-2-deoxyglucose positron emission tomography and computed tomography

OBJECTIVE

New potent tyrosine kinase inhibitors such as sorafenib are the most effective treatment for metastatic renal cell carcinoma (MRCC) today. In this study, we used [18F]-2-fluoro-2-deoxyglucose (FDG) with positron emission tomography (PET) combined with computed tomography (CT) to evaluate early effects of sorafenib in patients with MRCC.

METHODS

Ten patients, eight males and two females, with a mean age of 61 years (49-72 years), with MRCC were enrolled. A total of 52 lesions, two to nine lesions/patient, out of which 39 were soft lesions, were evaluated. The [18F]FDG-PET/CT was performed before treatment and after 1-2 months. A region of interest (ROI) was identified including the lesions where the glucose uptake was measured, calculating the average value within the ROI and using the cerebellum as the reference. The same ROI was measured in the subsequent FDG-PET. The sum of the diameters was measured in CT according to the Response Evaluation Criteria in Solid Tumors (RECIST). Sorafenib was given 400 mg twice daily orally.

RESULTS

After 1-2 months, the mean glucose uptake in all lesions decreased to 75% (32-105%) of initial values of ROI as measured by FDG-PET. The mean glucose uptake in soft lesions decreased to 71% (32-108%) and in skeletal lesions to 82% (53-101%). The sum of the diameters measured by CT decreased to 80% (57-94%) of the initial value in soft lesions according to the RECIST.

CONCLUSION

An early decrease in the mean glucose uptake was found in both soft and skeletal lesions after treatment with sorafenib. FDG-PET thus seems to be advantageous, compared with RECIST evaluation, which is limited to soft lesions.

Successful surgical resection of advanced gastrointestinal stromal tumor post neoadjuvent therapy

We report a case of a 48-year-old Indian male who presented with swelling and firmness in his left upper part of the abdomen of one month duration with anorexia and weight loss. Initial examination revealed an intra abdominal mass of around 16.8x11.0x24.5cm with minimal left sided pleural effusion. A biopsy from the mass confirmed the diagnosis of gastrointestinal stromal tumour (GISTs) as supported by immmunohistochemistry results which showed strong positivity for c-kit while stains for smooth muscle actin, desmin, myoglobin, S100 Protein and cytokerstin remained negative. The patient was not suitable for surgical intervention in view of advanced tumor, and Imatinib Mesylate 400mg daily was started with the aim of making the tumor operable. Such therapy lasted for twenty months and was tolerated well by the patient. It then resulted in gradual tumor regression, following which the patient underwent successful tumor resection. Post surgical resection patient had no radiological evidence of intra abdominal tumor but mild left sided pleural effusion with left lower lobe atelectasis. The patient had uneventful post operative recovery and he is currently on Imatinib mesylate and tolerating treatment well with mild skin rash. The experience with preoperative imatinib on surgical resection rates and post operative outcomes is limited especially with primary locally advanced GISTs. In our case successful surgical resection was possible for a huge locally advanced GIST with unusually prolonged treatment of twenty months with imatinib preoperatively.

Imatinib mesylate neoadjuvant treatment for rectal malignant gastrointestinal stromal tumor

Surgical treatments including radical resection and local excision remain the main treatment for primary rectal gastrointestinal stromal tumors (GISTs). However, since patients with high-grade rectal GISTs have a higher risk of tumor recurrence and a shorter life expectancy, neoadjuvant treatment is necessary. In this case report, the efficacy of imatinib mesylate (IM) as a neoadjuvant therapy was assessed in an old man with malignant rectal GIST. The patient received IM preoperative treatment for a short period of one and a half months; at the end of the IM treatment, computed tomography scanning showed a markedly reduced tumor size and cystic changes of the tissue. At that time, a function sphincter-sparing surgery was performed. The histological examination of the resected specimen detected no tumor cells, but residual blood vessels and scattered inflammatory lymphocytes. After surgery, the patient has been followed up without additional IM treatment and remained disease-free for 57 mo. This case indicates that IM neoadjuvant therapy can dramatically improve the prognosis of rectal malignant GIST.

Laparoscopic resection of sporadic synchronous gastric and jejunal gastrointestinal stromal tumors: report of a case

Multicentricity of gastrointestinal stromal tumors (GISTs) has been described only in patients with neurofibromatosis type 1 (NF1) or within the small intestine, and different pathogenetic mechanisms are involved. We report a case of synchronous sporadic gastric and jejunal GISTs, which were resected laparoscopically in a 67-year-old man. Immunohistochemical analysis revealed that both lesions were KIT (CD117)-positive, but that the gastric lesion was CD34-positive, whereas the jejunal one was Vimentin-, S-100-, and SMA-positive. Molecular analysis of mutations in KIT exons 9, 11, 13, and 17, and in PDGFRA exons 12 and 18 revealed the presence of a gastric sporadic GIST with a KIT mutation of the exon 11 and a jejunal sporadic GIST without KIT or PDGFRA mutations. To our knowledge, this is the first report of laparoscopically resected synchronous sporadic gastric and jejunal GISTs.

Analysis of a case with disappearance of the primary gastrointestinal stromal tumor and progressive liver metastases under long-term treatment with tyrosine kinase inhibitors

The response of gastrointestinal stromal tumors (GISTs) to tyrosine kinase receptor inhibitors (TKR-I) has been a breakthrough for small molecular therapy. We report here on the very different long-term outcome of a synchronous metastatic GIST with complete remission of the primary tumor and progressive liver metastases under TKR-I therapy. In 2003, a 52-year-old patient was diagnosed with gastric GIST and synchronous multiple liver metastases. Therapy with imatinib, 400 mg daily, was started immediately. Fifteen months later, the primary was no longer detectable by endoscopy. In 2006, progression of the liver metastases was observed. Mutation analysis of the initial biopsy specimen from the primary, as well as the biopsy from the three main liver metastases after 3 years of imatinib treatment, revealed the common KIT exon 11 deletion (W557_K558del) in all tumor samples. Two of the metastases had a separate secondary mutation in KIT exon 14 and 17, respectively, while the largest cystic metastatic lesion had no other mutation. Imatinib was then increased to a daily dose of 800 mg, and in April 2007 the treatment was changed to sunitinib. Fifty-two months after initial diagnosis, the patient died of liver failure. At no time point, relapse of the gastric primary tumor was observed. Whilst TKR-Is are commonly very effective in treating GISTs, the present case illustrates their varying effects regarding the clinical behavior and genetic variations within different tumors of the same patient after long-term treatment.

Surgical margin status and prognosis of gastrointestinal stromal tumor

BACKGROUND

Surgery is the best treatment for primary GIST and may be curative, but resection extension/completeness impact on the prognosis remains controversial. The authors aim was to evaluate the clinicopathological (CP) parameters and surgical margins status influence on GIST patients' outcome.

MATERIALS AND METHODS

The study evaluated 113 consecutive patients with sporadic GIST; the influence of CP parameters on recurrence-free survival (RFS) and disease-specific survival (DSS) was determined by univariate analysis (UA) and multivariate analysis (MA).

RESULTS

Of 104 cases, macroscopically complete resection was achieved in 96: R0 surgical margin status in 78 and R1 in 18. Recurrence rates (12.5%) were significantly lower in R0 (9.0%) than in R1 (27.8%). Tumor > 10 cm, mitotic count > 5/50 high power field (HPF), and high-risk GIST predicted poor RFS and DSS (UA). Disease-specific survival was significantly shorter after macroscopic incomplete (R2) resection, for mixed cellular morphology, and in tumors with necrosis (UA). High-risk GIST (p = 0.016) and R2 resection (p = 0.013) predicted poor DSS of patients (MA).

CONCLUSIONS

High risk and positive macroscopic surgical margin status are parameters associated with poor disease-specific survival in GIST patients.

Phase II trial of neoadjuvant/adjuvant imatinib mesylate (IM) for advanced primary and metastatic/recurrent operable gastrointestinal stromal tumor (GIST): early results of RTOG 0132/ACRIN 6665

BACKGROUND

Therapy for gastrointestinal stromal tumors (GIST) has changed significantly with the use of imatinib mesylate (IM). Despite the success of this drug in metastatic GIST, disease progression remains a perplexing clinical issue suggesting the need for multimodality management. There have been no prospective studies either evaluating the neoadjuvant use of IM in primary GIST or as a preoperative cytoreduction agent for metastatic GIST.

METHODS

RTOG 0132/ACRIN 6665 was a prospective phase II study evaluating safety and efficacy of neoadjuvant IM (600 mg/day) for patients with primary GIST or the preop use of IM in patients with operable metastatic GIST. The trial continued postop IM for 2 years.

RESULTS

Sixty-three patients were entered (52 analyzable), 30 patients with primary GIST (Group A) and 22 with recurrent metastatic GIST (Group B). Response (RECIST) in Group A was (7% partial, 83% stable, 10% unknown), in Group B (4.5% partial, 91% stable, 4.5% progression). Two-year progression free survival (Group A 83%, Group B 77%). Estimated overall survival (Group A 93%, Group B 91%). Complications of surgery and IM toxicity were minimal.

CONCLUSION

This trial represents the first prospective report of preop IM in GIST. This approach is feasible, requires multidisciplinary consultations, and is not associated with notable postop complications.

Inhibition of apoptosis by downregulation of hBex1, a novel mechanism, contributes to the chemoresistance of Bcr/Abl+ leukemic cells

Overexpression of multidrug resistance proteins (Mdrs) and enhanced antiapoptotic capability are two of the main mechanisms by which Bcr/Abl(+) chronic myeloid leukemia cells acquire drug resistance; however, it has been shown that Mdr-1 expression provides minimal protection against cell apoptosis induced by chemotherapeutic drugs. The mechanism by which cells acquire an enhanced antiapoptosis capacity in the drug-resistant process needs to be further understood. Here, we identified human brain expressed X-linked 1 (hBex1) as a downstream target of the p75 neurotrophin receptor pathway in imatinib-resistant K562 cells by comparing the gene expression profiles with the parent K562 cells. Silencing hBex1 inhibited imatinib-induced cell apoptosis and overexpression of hBex1-sensitized cells to imatinib-induced apoptosis. Further investigation revealed that hBex1 associates with protocadherin 10 (PCDH10). Silencing of pcdh10 attenuated apoptosis induced by imatinib in hBex1 transfected cells, suggesting that, in addition to Mdr and Bcl-2 family members, reduced expression of hBex1 can also inhibit imatinib-induced apoptosis. These data provide evidence that expression of hBex1 in leukemic cells is a novel mechanism by which chemoresistance is achieved and suggests that hBex1 is a potential molecular target for the development of novel leukemia treatments.