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

Medical Oncological Treatment for Patients with Gastrointestinal Stromal Tumour (GIST) - a Systematic Review

BACKGROUND

Chemotherapy is ineffective in treating patients with Gastrointestinal Stromal Tumour (GIST). However, several types of tyrosine kinase inhibitors have been investigated since the approval of imatinib in 2001. The purpose of this report was to systematically review studies on the efficacy of neoadjuvant, adjuvant, and lifelong medical oncological treatment of GIST.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed throughout the review process. The protocol was submitted to the International prospective register of systematic reviews database (ID 251724). A systematic literature search was performed, including phase II- and III studies of biological treatment, reporting on treatment effect in patients with GIST.

RESULTS

Of 308 identified publications, 42 studies were included in this review.

CONCLUSION

This review gives an overview of the existing evidence for approved lines of oncological treatments and potential alternatives for patients with GIST in the neoadjuvant-, adjuvant- and life-long setting.

BRD9 inhibition promotes PUMA-dependent apoptosis and augments the effect of imatinib in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are primarily characterized by activating mutations of tyrosine kinase or platelet-derived growth factor receptor alpha. Although the revolutionary therapeutic outcomes of imatinib are well known, the long-term benefits of imatinib are still unclear. The effects of BRD9, a recently identified subunit of noncanonical BAF complex (ncBAF) chromatin remodeling complexes, in GISTs are not clear. In the current study, we evaluated the functional role of BRD9 in GIST progression. Our findings demonstrated that the expression of BRD9 was upregulated in GIST tissues. The downregulation or inhibition of BRD9 could significantly reduce cellular proliferation, and facilitates apoptosis in GISTs. BRD9 inhibition could promote PUMA-dependent apoptosis in GISTs and enhance imatinib activity in vitro and in vivo. BRD9 inhibition synergizes with imatinib in GISTs by inducing PUMA upregulation. Mechanism study revealed that BRD9 inhibition promotes PUMA induction via the TUFT1/AKT/GSK-3β/p65 axis. Furthermore, imatinib also upregulates PUMA by targeting AKT/GSK-3β/p65 axis. In conclusion, our results indicated that BRD9 plays a key role in the progression of GISTs. Inhibition of BRD9 is a novel therapeutic strategy in GISTs treated alone or in combination with imatinib.

Coordinated targeting of CK2 and KIT in gastrointestinal stromal tumours

Background

Most gastrointestinal stromal tumours (GIST) are driven by activating oncogenic mutations of KIT/PDGFRA, which provide a compelling therapeutic target. Our previous studies showed that CDC37, regulated by casein kinase 2 (CK2), is a crucial HSP90 cofactor for KIT oncogenic function and a promising and more selective therapeutic target in GIST.

Methods

Biologic mechanisms of CK2-mediated CDC37 regulation were assessed in GISTs by immunoblotting, immunoprecipitations, knockdown and inactivation assays. The effects of a combination of KIT and CK2 inhibition were assessed by immunoblotting, cell viability, colony growth, cell cycle analysis, apoptosis, migration and invasiveness.

Results

CK2 overexpression was demonstrated by immunoblotting in GIST cell lines and patient biopsies. Treatment with a specific CK2 inhibitor, CX4945, leads to CDC37 dephosphorylation and inhibits KIT signalling in imatinib-sensitive and in imatinib-resistant GIST cell lines. Immunoprecipitation demonstrated that CK2 inhibition blocks KIT:HSP90:CDC37 interaction in GIST cells. Coordinated inhibition of CK2 and KIT by CX4945 (or CK2 shRNA) and imatinib, respectively, leads to increased apoptosis, anti-proliferative effects and cell cycle arrest and decreased p-AKT and p-S6 expression, migration and invasiveness in all GIST cell lines compared with either intervention alone, indicating additive effects of inhibiting these two important regulators of GIST biology.

Conclusion

Our findings suggest that combinatorial inhibition of CK2 and KIT warrants evaluation as a novel therapeutic strategy in GIST, especially in imatinib-resistant GIST.

Long-term efficacy of imatinib mesylate in patients with advanced Tenosynovial Giant Cell Tumor

Tenosynovial giant cell tumors (TGCT), are rare colony stimulating factor-1(CSF-1)-driven proliferative disorders affecting joints. Diffuse-type TGCT often causes significant morbidity due to local recurrences necessitating multiple surgeries. Imatinib mesylate (IM) blocks the CSF-1 receptor. This study investigated the long term effects of IM in TGCT. We conducted an international multi-institutional retrospective study to assess the activity of IM: data was collected anonymously from individual patients with locally advanced, recurrent or metastatic TGCT. Sixty-two patients from 12 institutions across Europe, Australia and the United States were identified. Four patients with metastatic TGCT progressed rapidly on IM and were excluded for further analyses. Seventeen of 58 evaluable patients achieved complete response (CR) or partial response (PR). One- and five-year progression-free survival rates were 71% and 48%, respectively. Thirty-eight (66%) patients discontinued IM after a median of 7 (range 1–80) months. Reported adverse events in 45 (78%) patients were among other edema (48%) and fatigue (50%), mostly grade 1–2 (89%). Five patients experienced grade 3–4 toxicities. This study confirms, with additional follow-up, the efficacy of IM in TGCT. In responding cases we confirmed prolonged IM activity on TGCT symptoms even after discontinuation, but with high rates of treatment interruption and additional treatments.

Cyclin D1 is a mediator of gastrointestinal stromal tumor KIT-independence

Oncogenic KIT or PDGFRA tyrosine kinase mutations are compelling therapeutic targets in most gastrointestinal stromal tumors (GISTs), and the KIT inhibitor, imatinib, is therefore standard of care for patients with metastatic GIST. However, some GISTs lose expression of KIT oncoproteins, and therefore become KIT-independent and are consequently resistant to KIT-inhibitor drugs. We identified distinctive biologic features in KIT-independent, imatinib-resistant GISTs as a step towards identifying drug targets in these poorly understood tumors. We developed isogenic GIST lines in which the parental forms were KIT oncoprotein-dependent, whereas sublines had loss of KIT oncoprotein expression, accompanied by markedly downregulated expression of the GIST biomarker, protein kinase C-theta (PRKCQ). Biologic mechanisms unique to KIT-independent GISTs were identified by transcriptome sequencing, qRT-PCR, immunoblotting, protein interaction studies, knockdown and expression assays, and dual-luciferase assays. Transcriptome sequencing showed that cyclin D1 expression was extremely low in two of three parental KIT-dependent GIST lines, whereas cyclin D1 expression was high in each of the KIT-independent GIST sublines. Cyclin D1 inhibition in KIT-independent GISTs had anti-proliferative and pro-apoptotic effects, associated with Rb activation and p27 upregulation. PRKCQ, but not KIT, was a negative regulator of cyclin D1 expression, whereas JUN and Hippo pathway effectors YAP and TAZ were positive regulators of cyclin D1 expression. PRKCQ, JUN, and the Hippo pathway coordinately regulate GIST cyclin D1 expression. These findings highlight the roles of PRKCQ, JUN, Hippo, and cyclin D1 as oncogenic mediators in GISTs that have converted, during TKI-therapy, to a KIT-independent state. Inhibitors of these pathways could be effective therapeutically for these now untreatable tumors.

Evidence mapping based on systematic reviews of therapeutic interventions for gastrointestinal stromal tumors (GIST)

Background

Gastrointestinal Stromal Tumours (GISTs) are the most common mesenchymal tumours. Currently, different pharmacological and surgical options are used to treat localised and metastatic GISTs, although this research field is broad and the body of evidence is scattered and expanding. Our objectives are to identify, describe and organise the current available evidence for GIST through an evidence mapping approach.

Methods

We followed the methodology of Global Evidence Mapping (GEM). We searched Pubmed, EMBASE, The Cochrane Library and Epistemonikos in order to identify systematic reviews (SRs) with or without meta-analyses published between 1990 and March 2016. Two authors assessed eligibility and extracted data. Methodological quality of the included systematic reviews was assessed using AMSTAR. We organised the results according to identified PICO questions and presented the evidence map in tables and a bubble plot.

Results

A total of 17 SRs met eligibility criteria. These reviews included 66 individual studies, of which three quarters were either observational or uncontrolled clinical trials. Overall, the quality of the included SRs was moderate or high. In total, we extracted 14 PICO questions from them and the corresponding results mostly favoured the intervention arm.

Conclusions

The most common type of study used to evaluate therapeutic interventions in GIST sarcomas has been non-experimental studies. However, the majority of the interventions are reported as beneficial or probably beneficial by the respective authors of SRs. The evidence mapping is a useful and reliable methodology to identify and present the existing evidence about therapeutic interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-017-0402-9) contains supplementary material, which is available to authorized users.

LAPAROSCOPIC RESECTION OF GASTROINTESTINAL STROMAL TUMORS (GIST)

BACKGROUND

Gastrointestinal mesenchymal or stromal tumors (GIST) are lesions originated on digestive tract walls, which are treated by surgical resection. Several laparoscopic techniques, from gastrectomies to segmental resections, have been used successfully.

AIM

Describe a single center experience on laparoscopic GIST resection.

METHOD

Charts of 15 operated patients were retrospectively reviewed. Thirteen had gastric lesions, of which ten were sub epithelial, ranging from 2-8 cm; and three were pure exofitic growing lesions. The remaining two patients had small bowel lesions. Surgical laparoscopic treatment consisted of two distal gastrectomies, 11 wedge gastric resections and two segmental enterectomies. Mechanical suture was used in the majority of patients except on six, which underwent resection and closure using manual absorbable sutures. There were no conversions to open technique.

RESULTS

Mean operative time was 1h 29 min±92 (40-420 min). Average lenght of hospital stay was three days (2-6 days). There were no leaks, postoperative bleeding or need for reintervention. Mean postoperative follow-up was 38±17 months (6-60 months). Three patients underwent adjuvant Imatinib treatment, one for recurrence five months postoperatively and two for tumors with moderate risk for recurrence .

CONCLUSION

Laparoscopic GIST resection, not only for small lesions but also for tumors above 5 cm, is safe and acceptable technique.

Neoplastic Diseases of the Small Bowel

The incidence of small bowel tumors is increasing over time. Until recently, their diagnosis was delayed and it was often reached only at the time of surgery. New diagnostic tools, such as capsule endoscopy, device-assisted enteroscopy, and dedicated small bowel cross-sectional imaging techniques, have been introduced recently in clinical practice. The combination of these tools allows medical practitioners to detect small bowel tumors at an early stage and to reach a definite diagnosis before surgery, thus enabling minimally invasive treatments.

Predictive features of CT for risk stratifications in patients with primary gastrointestinal stromal tumour

PURPOSE

To determine the predictive CT imaging features for risk stratifications in patients with primary gastrointestinal stromal tumours (GISTs).

MATERIALS AND METHODS

One hundred and twenty-nine patients with histologically confirmed primary GISTs (diameter >2 cm) were enrolled. CT imaging features were reviewed. Tumour risk stratifications were determined according to the 2008 NIH criteria where GISTs were classified into four categories according to the tumour size, location, mitosis count, and tumour rupture. The association between risk stratifications and CT features was analyzed using univariate analysis, followed by multinomial logistic regression and receiver operating characteristic (ROC) curve analysis.

RESULTS

CT imaging features including tumour margin, size, shape, tumour growth pattern, direct organ invasion, necrosis, enlarged vessels feeding or draining the mass (EVFDM), lymphadenopathy, and contrast enhancement pattern were associated with the risk stratifications, as determined by univariate analysis (P < 0.05). Only lesion size, growth pattern and EVFDM remained independent risk factors in multinomial logistic regression analysis (OR = 3.480-100.384). ROC curve analysis showed that the area under curve of the obtained multinomial logistic regression model was 0.806 (95 % CI: 0.727-0.885).

CONCLUSION

CT features including lesion size, tumour growth pattern, and EVFDM were predictors of the risk stratifications for GIST.

KEY POINTS

• CT features were of predictive value for risk stratification of GISTs. • Tumour size, growth patterns, and EVFDM were risk predictors of GISTs. • Large size, mixed growth pattern, or EVFDM indicated high risk GIST.

Treatment patterns, prescribing decision drivers, and predictors of complete response following disease recurrence in gastrointestinal stromal tumor patients-a chart extract-based approach

PURPOSE

The aim of this study was to investigate tumor characteristics, treatment patterns, and outcomes in recurrent KIT + GIST patients treated in a community practice setting.

METHODS

An online tool was used to retrieve data on 410 patients treated with adjuvant imatinib mesylate (IM) for primary resectable KIT + GIST, who discontinued, had a recurrence, and then restarted IM or initiated sunitinib. Tumor characteristics at recurrence, treatment patterns, and factors associated with post-recurrence complete response (CR) achievement were analyzed.

RESULTS

About 72.7 % of patients did not have surgery post-recurrence as majority of them had unresectable (45 %), metastatic (40 %), or multifocal tumors (62.4 %). Following recurrence, 76.6 % of patients were re-started on IM and 23.4 % on sunitinib; patients were 7.37 times more likely to re-start IM if initial treatment duration was ≤18 months (p < 0.001). Patients were also more likely to re-start IM if recurrence occurred >12 months post-discontinuation, or they had a recurrence inside the GI system, lower or unknown Fletcher risk score at primary diagnosis, or lower mitotic rate, (odds ratio (OR) = 3.54, p < 0.001; OR = 2.64, p = 0.006; OR = 2.55, p = 0.007; and OR = 2.45, p = 0.002, respectively). About 22.4 % achieved CR; patients were more likely to achieve CR if they had unifocal tumor at recurrence, inside the GI system, of ≤2 cm, or had lower mitotic rate (OR = 2.61, p < 0.001; OR = 2.27, p = 0.036; OR = 2.16, p = 0.023, OR = 1.87, p = 0.017, respectively).

CONCLUSIONS

IM treatment duration at primary diagnosis, time to develop recurrence after IM discontinuation, tumor location, and mitotic rate at recurrence were the main prescribing decision drivers. Tumor characteristics were the most important factor in achieving CR following c-KIT inhibitor retreatment.

The economic burden of gastrointestinal stromal tumor (GIST) recurrence in patients who have received adjuvant imatinib therapy

OBJECTIVE

To estimate the economic burden of gastrointestinal stromal tumor (GIST) recurrence in patients who received imatinib adjuvant therapy.

METHODS

Data from the MarketScan and PharmMetrics databases between January 2000 and March 2013 were extracted. Patients who had received at least one diagnosis of GIST, had undergone a primary surgery for GIST, and had received at least one prescription for imatinib were included in the analysis. An algorithm was applied to identify those who had a subsequent GIST recurrence. Patients who experienced a recurrence and those who did not have a recurrence were compared for differences in healthcare utilization measures and healthcare costs within 6 months after the recurrence, while adjusting for potential confounding factors.

RESULTS

A total of 540 patients with primary resectable GIST who received imatinib adjuvant therapy were identified, including 444 (82.2%) patients who did not experience GIST recurrence and 96 (17.8%) patients who did experience recurrence. Patients who experienced GIST recurrence utilized significantly more healthcare resources in all categories than patients who did not have a recurrence, including the number of hospitalizations, days of hospitalization, emergency room visits, outpatient visits, and other medical services (all p-values <0.01). The total healthcare cost was significantly higher for patients with GIST recurrence, with a difference of $4464 per patient per month (p < 0.01). Both the medical and pharmacy costs were significantly higher with adjusted differences of $3488 and $1423 per patient per month, respectively (both p-values <0.01).

CONCLUSIONS

Patients who had GIST recurrence after surgical resection incurred significantly more healthcare resource utilization and greater healthcare costs within 6 months after the recurrence than patients who did not have recurrence. These findings suggest that GIST recurrence is associated with a substantial economic burden.

Preoperative imatinib for patients with primary unresectable or metastatic/recurrent gastrointestinal stromal tumor

OBJECTIVES

Despite its rising popularity, reports on the use of preoperative imatinib mesylate (IM) in patients with advanced gastrointestinal stromal tumor (GIST) are limited. This study aims to explore the clinical efficacy of preoperative IM in patients with primarily unresectable or metastatic/recurrent GIST.

METHODS

Between September 2009 and February 2014, patients with primarily unresectable or metastatic/recurrent GIST treated by a single medical team were recruited and considered for preoperative IM therapy. Re-examination was conducted regularly and abdominal enhanced CT data, blood biochemistry and responses to IM were recorded.

RESULTS

A total of 18 patients were enrolled, including 13 with a primary tumor (7 stomach, 3 small bowel, 2 rectal and 1 pelvic tumor) and 5 with recurrent or metastatic GIST (2 with liver metastasis, 2 with anastomotic recurrence and 1 with pelvic GIST). The median follow-up time was 9.5 months (range of 3-63). The median tumor sizes before and after initiation of IM treatment were 9.1 cm and 6.0 cm (p=0.003) based on the CT findings, respectively. All patients showed a decrease in tumor burden and the median tumor size reduction was 35%. Sixteen of the 18 patients showed a partial response to IM and two possessed stable disease. Nine of the 18 patients (50%) underwent surgical resection of primary or metastatic/recurrent tumors, with a median of 7 months of IM therapy. One case each of multivisceral resection and tumor recurrence were noted.

CONCLUSIONS

IM as a preoperative therapy is feasible and safe for unresectable or metastatic/recurrent GIST that can effectively decrease tumor size, facilitating resection.

Systematic review of the side effects associated with tyrosine kinase inhibitors used in the treatment of gastrointestinal stromal tumours on behalf of the EORTC Quality of Life Group

Tyrosine kinase inhibitors (TKIs) have revolutionised the treatment of advanced gastrointestinal stromal tumours (GISTs). Imatinib is approved as first line therapy and sunitinib is used in cases of imatinib resistance or intolerance. Compared with conventional treatments, TKIs are delivered over longer periods of time and are more specific in their targets (i.e., molecularly targeted), thus presenting different side effect profiles. We review the safety profiles of imatinib and sunitinib, documenting a total of 95 side effects including patient based as well as medically defined outcomes. Gastrointestinal complaints, particularly diarrhoea and nausea, oedema, fatigue and haematological disorders, notably anaemia, are amongst the most prevalent side effects. While there is overlap between the side effect profiles of imatinib and sunitinib, important differences emerge in the frequencies of oedema, hypertension, thyroid functioning, muscle and joint pains, as well as skin and oral conditions. Awareness of potential side effects is informative to both clinician and patient in terms of treatment decision making and can have important implications for treatment adherence and clinical outcome.

Optimized dose of imatinib for treatment of gastrointestinal stromal tumors: a meta-analysis

OBJECTIVE

To investigate the efficacy and safety of standard-dose versus high-dose imatinib.

METHODS

After a systematic review of English language articles, five studies including 2008 patients were eligible for the meta-analysis. Data extracted from each study were synthesized into overall odds ratios (OR).

RESULTS

The overall OR for the high dose vs standard dose was 1.19 (95% CI 1.00-1.42) and the Z-score for the overall effect was 1.93 (P = 0.054), suggesting that high-dose imatinib added no survival benefits. The dose-related toxicity was also assessed in the same way. The rates of rash, hemorrhage, nausea, vomiting and taste disturbance increased as dose increased (P < 0.05), whereas the incidence of headache, abdominal pain, edema, fatigue, anemia, infection, muscle cramp and constipation was nearly identical and showed no significant difference.

CONCLUSIONS

Imatinib at a standard dose produces a similar effect to that at a high dose. The severity of the toxicity is associated with the dose of imatinib. However, larger and randomized studies are needed to draw definitive conclusions.

Comparison of the long-term risk of recurrence and other clinical outcomes in GIST patients receiving imatinib as adjuvant therapy--a retrospective chart extract-based approach

PURPOSE

To compare characteristics of patients, the risk of recurrence, and mortality among adult patients with primary resectable gastrointestinal stromal tumor (GIST) receiving short-term (6-12 months) versus long-term (≥ 24 months) imatinib therapy.

METHODS

Detailed information on primary resectable KIT-positive GIST patients initiated on imatinib adjuvant therapy was retrospectively collected for short- and long-term imatinib patients from 318 US oncologists using an online data collection form. Patient characteristics were compared using Wilcoxon and Chi-square tests. Disease recurrence and mortality rates were compared using multivariate Cox proportional hazard models.

RESULTS

Among the 406 short-term and 406 long-term imatinib patients, the median follow-up was 916 and 970 days, respectively. While patients generally had similar demographic characteristics, the short-term group had a higher prevalence of cardiovascular and ischemic heart diseases and patients in the long-term group had a higher pre-surgery risk profile. This finding was consistent with the main reason reported by oncologists for prescribing adjuvant imatinib over longer duration, i.e., patient risk profile. Disease recurrence [5.9 versus 1.2 %, (p < .001)] and mortality rates [7.1 % versus 2.0 %, (p < .001)] were higher in short- versus long-term patients. The adjusted risk of recurrence was 5.30 times (p < .001) higher, and mortality risk was 4.02 times (p < .001) higher in short- versus long-term patients.

CONCLUSIONS

Patient risk profile is an important factor in oncologists' decisions to prescribe adjuvant imatinib. Despite the higher risk profile observed in long-term patients, the long-term use of imatinib was associated with a reduction in long-term risk of disease recurrence and mortality.

Efficacy and safety evaluation of two doses of imatinib for the treatment of advanced gastrointestinal stromal tumors (GISTs)

BACKGROUND AND OBJECTIVE

Imatinib is approved worldwide for use in gastrointestinal stromal tumours (GISTs). To evaluate the efficacy and safety of two dose of imatinib treatment for patients with GISTs, a meta-analysis was performed.

METHODS

Electronic search of the PubMed and EMBASE, which have articles published between 1980 and February 2012, was conducted to select studies for this meta-analysis.

RESULTS

Five articles with a total number 1861 of advanced GISTs patients were involved in this meta-analysis. There was a slight but significant 2-year PFS advantage with high-dose group (OR=1.25, 95% CIs=1.03-1.52, P=0.03), but not in the 2-year OS (OR=1.02, 95% CIs=0.84-1.24, P=0.87), CR (OR=1.02, 95% CIs=0.66-1.58, P=0.93), and PR (OR=1.13, 95% CIs=0.94-1.36, P=0.20). In safety, the high-dose group increased the incidence of above grade 3 toxicity (OR=2.05, 95% CIs=1.70-2.48, P<0.00001), particular in the blood toxicity, skin disorders, nausea and so on.

CONCLUSIONS

This analysis confirms a slight 2-year PFS advantage of high-dose imatinib, but imatinib dose escalation could not lead to any other major clinical benefits, and brought more toxic effects for patients.

Regulation of cell proliferation through a KIT-mediated mechanism in benign prostatic hyperplasia

BACKGROUND

We investigated the role of the KIT-mediated mechanism in benign prostatic hyperplasia (BPH), and discuss the pathophysiology of BPH and a candidate target of BPH medical therapy.

METHODS

We performed RT-PCR, Western blotting, and immunohistochemistry to examine the expression of KIT in the prostate using a human prostate stromal cell line (PrSC) and human prostate. To investigate the pathophysiological function of KIT, the effects of KIT ligand, stem cell factor (SCF), and imatinib mesylate on cell proliferation were investigated using PrSC. Additionally, we compared the expression level and distribution of KIT in normal prostate and BPH of humans to clarify the contribution of KIT to the pathogenesis of BPH.

RESULTS

KIT was expressed in PrSC and human prostate, indicating that these samples are suitable for examining the function of KIT. Immunohistochemical analysis demonstrated that KIT was localized in interstitial cells (ICs) of the stromal component in human prostate. Administration of imatinib mesylate dose-dependently inhibited cell proliferation of PrSC with downregulation of JAK2 and STAT1, which are the main pathways downstream of SCF/KIT signal. SCF promoted cell proliferation of PrSC with upregulation of JAK2 and STAT1. KIT expression and the number of KIT-positive ICs in BPH were found to be significantly larger than in normal prostate.

CONCLUSIONS

This is the first report to suggest that KIT regulates cell proliferation in the prostate and plays a significant role in the pathophysiology of BPH. Our study may lead to a greater understanding of the mechanism of BPH and provide a therapeutic target.

Endoscopic therapy for gastric stromal tumors originating from the muscularis propria

AIM: To explore endoscopic therapy methods for gastric stromal tumors originating from the muscularis propria.

METHODS: For 69 cases diagnosed as gastric stromal tumors originating from the muscularis propria, three types of endoscopic therapy were selected, based on the size of the tumor. These methods included endoscopic ligation and resection (ELR), endoscopic submucosal excavation (ESE) and endoscopic full-thickness resection (EFR). The wound surface and the perforation of the gastric wall were closed with metal clips. Immunohistostaining for CD34, CD117, Dog-1, S-100 and smooth muscle actin (SMA) was performed on the resected tumors.

RESULTS: A total of 38 cases in which the tumor size was less than 1.2 cm were treated with ELR; three cases were complicated by perforation, and the perforations were closed with metal clips. Additionally, 18 cases in which the tumor size was more than 1.5 cm were treated with ESE, and no perforation occurred. Finally, 13 cases in which the tumor size was more than 2.0 cm were treated with EFR; all of the cases were complicated by artificial perforation, and all of the perforations were closed with metal clips. All of the 69 cases recovered with medical treatment, and none required surgical operation. Immunohistostaining demonstrated that among all of the 69 gastric stromal tumors diagnosed by gastroscopy, 12 cases were gastric leiomyomas (SMA-positive), and the other 57 cases were gastric stromal tumors.

CONCLUSION: Gastric stromal tumors originating from the muscularis propria can be treated successfully with endoscopic techniques, which could replace certain surgical operations and should be considered for further application.

Effectiveness of adjuvant imatinib in patients with gastrointestinal stromal tumor: results of a population-based, matched-cohort study

OBJECTIVE

Data are limited on the use of adjuvant imatinib in patients with gastrointestinal stromal tumor (GIST) outside of clinical trials. This retrospective, population-based, matched-cohort study evaluated adjuvant imatinib treatment patterns, assessed impact on clinical outcomes, and estimated effectiveness based on number needed to treat (NNT).

RESEARCH DESIGN AND METHODS

GIST-related claims from the PharMetrics claims database were included (2000-2010). A stepwise identification algorithm identified appropriate patients based on GIST-related ICD-9-CM codes, who were classified as 'imatinib (IM) patients' receiving imatinib within 84 days post-surgery and 'non-imatinib (non-IM) patients' undergoing surgery but not receiving imatinib during the study period. The primary composite outcome was based on incidence of a second GIST-related surgery and long-term follow-up in the matched cohorts. IM patients were matched with up to eight non-IM patients on age, gender, ICD-9-CM code, and first surgery date.

RESULTS

A total of 118 IM and 4088 non-IM patients with possible GIST ICD-9s and surgery were included. The median duration between first and second surgeries was significantly longer in IM than non-IM patients (488 vs. 290 days; p = 0.0005). IM patients also had longer median follow-up from initial surgery to composite outcome (433 vs. 320 days; p = 0.002). Adherence to IM, measured by medication possession ratio, was 0.83 and 0.73 during the first and second years of treatment, respectively. IM patients were less likely to have the composite outcome compared with non-IM patients (hazard ratio = 0.501; p = 0.0005). The NNT to prevent one outcome was 4.

CONCLUSIONS

Patients receiving adjuvant imatinib treatment were less likely to have second surgery or be lost to follow-up, and had a longer interval to second surgery. Although treatment with adjuvant imatinib in patients with primary GIST is effective, adherence to imatinib and treatment duration are less than recommended by current treatment guidelines.

Esophageal gastrointestinal stromal tumor: report of 7 patients

Abstract Purpose: To evaluate imaging features of esophageal gastrointestinal stromal tumors (GIST) with clinical and histopathologic correlation and imaging follow-up. Materials and methods: In this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study, 14 patients with pathologically proven esophageal GIST seen from January 2001 to October 2011, 7 patients (4 women; mean age 70 years, range 56–87 years) who had imaging of primary tumor and follow-up imaging at our institution were included. Imaging studies were evaluated by 3 radiologists in consensus. Location, size and imaging features of primary tumor and metastases, if any, were recorded, and correlated with pathologic (histopathologic subtype, presence of necrosis, mitotic rate, immunohistochemical profile) and clinical (treatment-related changes, distant spread and outcome) parameters. Results: Of 7 tumors, 5 were located in the lower esophagus and 2 in mid-esophagus. Four were intraluminal, 2 were exophytic, and 1 was intramural. All 7 patients underwent computed tomography (CT); tumors appeared as well-circumscribed, hypoattenuating masses showing mild enhancement, with mean size of 5.7 × 4.2 cm. Necrosis and calcification were seen in 1 tumor each. Five patients underwent fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT. GISTs were FDG avid with mean standardized uptake value (SUV)_max of 9.5 (4.5–12.3). All tumors were positive for KIT (7/7) and CD34 (6/6). Distant metastases to liver and pleura were seen in 1 patient. On imatinib treatment, the tumors responded with decreased attenuation values and unchanged size on CT, and decreased SUV_max of primary tumor and metastases on FDG-PET/CT. Conclusion: Esophageal GISTs are well-circumscribed, FDG-avid, hypoattenuating masses that can metastasize to liver and pleura, and respond to imatinib treatment with decreased attenuation value on CT and decreased SUV_max on FDG-PET/CT.

Molecular approaches to personalizing management of ovarian cancer

Cytoreductive surgery and empirical combination chemotherapy have improved 5-year survival for ovarian cancer patients, but have not increased the overall rate of cure. Poor outcomes relate, at least in part, to late diagnosis and to the persistence of dormant ovarian cancer cells that have resisted conventional drugs. Increased understanding of the molecular, cellular and clinical biology of ovarian cancer must be translated into personalized therapy with conventional and targeted agents as well as personalized detection of high-grade cancers in early stages. Different strategies will be required to treat low-grade and high-grade serous cancers as well as other histotypes. Activating mutations of Ras and Raf can be targeted in low-grade cancers. Activation of the PI3K pathway-PI3Kness-and inactivation of BRCA function-BRCAness-can be targeted in high-grade lesions. Inhibition of multiple pathways will be required. Sensitivity of primary cancers to paclitaxel and platinum can be modulated by inhibiting kinases and other molecules that regulate the cell cycle. Dormant ovarian cancer cells may depend upon autophagy, cytokines and growth factors for survival. Early detection can utilize two stage strategies where rising serum biomarker levels prompt imaging in a small fraction of women. Screening can be personalized by taking into account each woman's baseline biomarker levels.

Gastrointestinal stromal tumors

INTRODUCTION

The gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the intestinal tract, known to be refractory to conventional chemotherapy or radiation. Its pathogenesis is defined by mutations within the KIT and PDGFRA gene, which constitutively activate KIT and PDGFRA oncoproteins, and serve as crucial diagnostic and therapeutic targets.

DISCUSSION

Besides surgery, therapy with imatinib mesylate, which inhibits KIT kinase activity, represents the other cornerstone for the treatment of GIST. Still, the only curative option for GIST is given after complete surgical removal even in a metastatic setting, but recurrence is common, and the risk can be defined by surgical factors like incomplete resection, intraperitoneal rupture, or bleeding and tumor associated factors like tumor size, mitotic index, or localization.

CONCLUSION

Consequently, adjuvant therapy with imatinib mesylate or other tyrosine kinase inhibitors is recommended for high-risk patients after complete resection. For unresectable and advanced GIST, a partial response or stable disease can be achieved in about 80% of patients with imatinib mesylate.

Complex effects of imatinib on spontaneous and oxytocin-induced contractions in human non-pregnant myometrium

Human myometrium includes two important cell populations involved in its contractility: smooth muscle fibers and interstitial cells. The pacemaking mechanism is not yet identified, but it is possible that myometrial smooth muscle cells contract in response to a signal generated by c-kit positive interstitial cells. The aim of this study was to investigate the effects of imatinib as a c-kit receptor antagonist on the spontaneous or oxytocin (OT) induced contractions of human non-pregnant myometrium in vitro. Myometrial strips were obtained from non-pregnant women (reproductive age) undergoing hysterectomy for benign indications. The strips were suspended in organ baths for recording of isometric tension. Imatinib effects were assessed on spontaneous contraction and after preexposure to OT.Direct exposure of myometrial strips to imatinib inhibits both amplitude and frequency of contractions (80-320 μM) in a dose dependent manner. Amplitude reverted back to 90% of the baseline amplitude by consequent addition of imatinib (until 480 μM). Total inhibition of myometrial contraction was obtained after addition of OT 60 nM. If myometrium was pre-exposed to OT (320 nM), imatinib 80-160 μm increased amplitude, while decreasing frequency. These data provide evidence that telocytes may be involved as modulators of the spontaneous contractions of the non-pregnant human uterus, via a tyrosine-kinase independent signaling pathway.

Cambogin is preferentially cytotoxic to cells expressing PDGFR

Platelet-derived growth factor receptors (PDGFRs) have been implicated in a wide array of human malignancies, including medulloblastoma (MB), the most common brain tumor of childhood. Although significant progress in MB biology and therapeutics has been achieved during the past decades, MB remains a horrible challenge to the physicians and researchers. Therefore, novel inhibitors targeting PDGFR signaling pathway may offer great promise for the treatment of MB. In the present study, we investigated the cytotoxicity and mechanisms of cambogin in Daoy MB cells. Our results show that cambogin triggers significant S phase cell cycle arrest and apoptosis via down regulation of cyclin A and E, and activation of caspases. More importantly, further mechanistic studies demonstrated that cambogin inhibits PDGFR signaling in Daoy and genetically defined mouse embryo fibroblast (MEF) cell lines. These results suggest that cambogin is preferentially cytotoxic to cells expressing PDGFR. Our findings may provide a novel approach by targeting PDGFR signaling against MB.

Epidemiology of cancer of the small intestine

Cancer of the small intestine is very uncommon. There are 4 main histological subtypes: adenocarcinomas, carcinoid tumors, lymphoma and sarcoma. The incidence of small intestine cancer has increased over the past several decades with a four-fold increase for carcinoid tumors, less dramatic rises for adenocarcinoma and lymphoma and stable sarcoma rates. Very little is known about its etiology. An increased risk has been noted for individuals with Crohn’s disease, celiac disease, adenoma, familial adenomatous polyposis and Peutz-Jeghers syndrome. Several behavioral risk factors including consumption of red or smoked meat, saturated fat, obesity and smoking have been suggested. The prognosis for carcinomas of the small intestine cancer is poor (5 years relative survival < 30%), better for lymphomas and sarcomas, and best for carcinoid tumors. There has been no significant change in long-term survival rates for any of the 4 histological subtypes. Currently, with the possible exceptions of obesity and cigarette smoking, there are no established modifiable risk factors which might provide the foundation for a prevention program aimed at reducing the incidence and mortality of cancers of the small intestine. More research with better quality and sufficient statistical power is needed to get better understanding of the etiology and biology of this cancer. In addition, more studies should be done to assess not only exposures of interest, but also host susceptibility.