Primary localized rectal/pararectal gastrointestinal stromal tumors: results of surgical and multimodal therapy from the French Sarcoma group.

BACKGROUND: Rectal and pararectal gastrointestinal stromal tumors (GISTs) are rare. The optimal management strategy for primary localized GISTs remains poorly defined. METHODS: We conducted a retrospective analysis of 41 patients with localized rectal or pararectal GISTs treated between 1991 and 2011 in 13 French Sarcoma Group centers. RESULTS: Of 12 patients who received preoperative imatinib therapy for a median duration of 7 (2-12) months, 8 experienced a partial response, 3 had stable disease, and 1 had a complete response. Thirty and 11 patients underwent function-sparing conservative surgery and abdominoperineal resection, respectively. Tumor resections were mostly R0 and R1 in 35 patients. Tumor rupture occurred in 12 patients. Eleven patients received postoperative imatinib with a median follow-up of 59 (2.4-186) months. The median time to disease relapse was 36 (9.8-62) months. The 5-year overall survival rate was 86.5%. Twenty patients developed local recurrence after surgery alone, two developed recurrence after resection combined with preoperative and/or postoperative imatinib, and eight developed metastases. In univariate analysis, the mitotic index (≤5) and tumor size (≤5 cm) were associated with a significantly decreased risk of local relapse. Perioperative imatinib was associated with a significantly reduced risk of overall relapse and local relapse. CONCLUSIONS: Perioperative imatinib therapy was associated with improved disease-free survival. Preoperative imatinib was effective. Tumor shrinkage has a clear benefit for local excision in terms of feasibility and function preservation. Given the complexity of rectal GISTs, referral of patients with this rare disease to expert centers to undergo a multidisciplinary approach is recommended.

Outcome of Patients with Platelet-Derived Growth Factor Receptor Alpha-Mutated Gastrointestinal Stromal Tumors in the Tyrosine Kinase Inhibitor Era.

PURPOSE: Platelet-derived growth factor receptor-alpha (PDGFRA) mutations are found in approximately 5% to 7% of advanced gastrointestinal stromal tumors (GIST). We sought to extensively assess the activity of imatinib in this subgroup. EXPERIMENTAL DESIGN: We conducted an international survey among GIST referral centers to collect clinical data on patients with advanced PDGFRA-mutant GISTs treated with imatinib for advanced disease. RESULTS: Fifty-eight patients were included, 34 were male (59%), and median age at treatment initiation was 61 (range, 19-83) years. The primary tumor was gastric in 40 cases (69%). Thirty-two patients (55%) had PDGFRA-D842V substitutions whereas 17 (29%) had mutations affecting other codons of exon 18, and nine patients (16%) had mutation in other exons. Fifty-seven patients were evaluable for response, two (4%) had a complete response, eight (14%) had a partial response, and 23 (40%) had stable disease. None of 31 evaluable patients with D842V substitution had a response, whereas 21 of 31 (68%) had progression as their best response. Median progression-free survival was 2.8 [95% confidence interval (CI), 2.6-3.2] months for patients with D842V substitution and 28.5 months (95% CI, 5.4-51.6) for patients with other PDGFRA mutations. With 46 months of follow-up, median overall survival was 14.7 months for patients with D842V substitutions and was not reached for patients with non-D842V mutations. CONCLUSIONS: This study is the largest reported to date on patients with advanced PDGFRA-mutant GISTs treated with imatinib. Our data confirm that imatinib has little efficacy in the subgroup of patients with D842V substitution in exon 18, whereas other mutations appear to be sensitive to imatinib. Clin Cancer Res; 18(16); 4458-64. ©2012 AACR.

Cancer testis antigen expression in gastrointestinal stromal tumors: new markers for early recurrence.

Cancer testis antigens (CTAs) are expressed in a variety of malignant tumors but not in any normal adult tissues except germ cells and occasionally placenta. Because of this tumor-associated pattern of expression, CTAs are regarded as potential vaccine targets. The expression of CTAs in gastrointestinal stromal tumors (GIST) has not been analyzed systematically previously. The present study was performed to analyze the expression of CTA in GIST and to determine if CTA expression correlates with prognosis. Thirty-five GIST patients were retrospectively analyzed for their expression of CTAs by immunohistochemistry using the following monoclonal antibodies (mAb/antigen): MA454/MAGE-A1, M3H67/MAGE-A3, 57B/MAGE-A4, CT7-33/MAGE-C1 and E978/NY-ESO-1. Fourteen tumors (40%) expressed 1 or more of the 5 CTAs tested. Fourteen percent (n = 5/35) were positive for MAGE-A1, MAGE-A3 or MAGE-A4, respectively. Twenty-six percent (n = 9/35) stained positive for MAGE-C1 and 20% (n = 7/35) for NY-ESO-1. A highly significant correlation between CTA expression and tumor recurrence risk was observed (71% vs. 29%; p = 0.027). In our study population, the high-risk GIST expressed CTAs more frequently than low-risk GIST (p = 0.012). High-risk GISTs which stained positive for at least 1 CTA, recurred in 100% (n = 25) of the cases. This is the first study analyzing CTA expression in GIST and its prognostic value for recurrence. The CTA staining could add information to the individual patient prognosis and represent an interesting target for future treatment strategies.

Clinical experience to date with nilotinib in gastrointestinal stromal tumors.

Nilotinib, a novel tyrosine kinase inhibitor (TKI) that inhibits BCR-ABL, the stem cell factor receptor (KIT), and platelet-derived growth factor receptor-alpha (PDGFRα), is approved for the treatment of patients with newly diagnosed Philadelphia chromosome-positive chronic myelogenous leukemia (CML) and those with CML that is imatinib-resistant or -intolerant. Due to its potent inhibition of KIT and PDGFRα--the two tyrosine kinases that are the central oncogenic mechanisms of gastrointestinal stromal tumors (GIST)--nilotinib also has been investigated for potential efficacy and safety in patients with GIST who have progressed on other approved treatments. Initial results have been encouraging, as nilotinib has demonstrated clinical efficacy and safety in a phase I trial as either a single agent or in combination with imatinib, as well as in heavily pretreated patients with GIST in a compassionate use program. In addition, the phase III trial of nilotinib versus best supportive care (with or without a TKI at the investigator's discretion) indicated that nilotinib may have efficacy in some third-line patients. Furthermore, the Evaluating Nilotinib Efficacy and Safety in Clinical Trials (ENEST g1 trial), a phase III randomized, open-label study comparing the safety and efficacy of imatinib versus nilotinib in the first-line treatment of patients with GIST, is currently under way. Other studies with nilotinib either have been initiated or are in development. Based on published and accruing clinical data, nilotinib shows potential as a new drug in the clinician's armamentarium for the management of GIST.

MR features of gastrointestinal stromal tumors.

We report on two patients presenting with gastrointestinal stromal tumors (GIST). The important tumor size and the marked tissular hypersignal seen on T2-weighted magnetic resonance images (MRI) should be considered as magnetic resonance (MR) features strongly indicating diagnosis of GIST.

Rôle du pathologiste dans la prise en charge des tumeurs stromales gastro-intestinales (GIST) [The role of the pathologist in the management of gastrointestinal stromal tumors (GIST)]

Considerable progress was realized these last years in the understanding of the molecular mechanisms and the treatment of the GIST. Their diagnosis remains based on the morphology and immunohistochemistry. The evaluation of GIST prognosis was till know difficult to establish but a new histopronostic classification currently used allows a better therapeutic approach. The search for KIT and PDGFRA mutations is recommended to adapt a targeted therapy by KIT inhibitors. The pathologist plays a crucial role in the management of the GIST because it is on him that is based the diagnosis, the evaluation of the prognosis and the treatment (surgery and kit inhibitors).

Correlations between imatinib pharmacokinetics, pharmacodynamics, adherence, and clinical response in advanced metastatic gastrointestinal stromal tumor (GIST): An emerging role for drug blood level testing?

Imatinib is the standard of care for patients with advanced metastatic gastrointestinal stromal tumors (GIST), and is also approved for adjuvant treatment in patients at substantial risk of relapse. Studies have shown that maximizing benefit from imatinib depends on long-term administration at recommended doses. Pharmacokinetic (PK) and pharmacodynamic factors, adherence, and drug-drug interactions can affect exposure to imatinib and impact clinical outcomes. This article reviews the relevance of these factors to imatinib's clinical activity and response in the context of what has been demonstrated in chronic myelogenous leukemia (CML), and in light of new data correlating imatinib exposure to response in patients with GIST. Because of the wide inter-patient variability in drug exposure with imatinib in both CML and GIST, blood level testing (BLT) may play a role in investigating instances of suboptimal response, unusually severe toxicities, drug-drug interactions, and suspected non-adherence. Published clinical data in CML and in GIST were considered, including data from a PK substudy of the B2222 trial correlating imatinib blood levels with clinical responses in patients with GIST. Imatinib trough plasma levels <1100ng/mL were associated with lower rates of objective response and faster development of progressive disease in patients with GIST. These findings have been supported by other analyses correlating free imatinib (unbound) levels with response. These results suggest a future application for imatinib BLT in predicting and optimizing therapeutic response. Nevertheless, early estimates of threshold imatinib blood levels must be confirmed prospectively in future studies and elaborated for different patient subgroups.

Absence of progression as assessed by response evaluation criteria in solid tumors predicts survival in advanced GI stromal tumors treated with imatinib mesylate: the intergroup EORTC-ISG-AGITG phase III trial.

PURPOSE: From February 2001 to February 2002, 946 patients with advanced GI stromal tumors (GISTs) treated with imatinib were included in a controlled EORTC/ISG/AGITG (European Organisation for Research and Treatment of Cancer/Italian Sarcoma Group/Australasian Gastro-Intestinal Trials Group) trial. This analysis investigates whether the response classification assessed by RECIST (Response Evaluation Criteria in Solid Tumors), predicts for time to progression (TTP) and overall survival (OS). PATIENTS AND METHODS: Per protocol, the first three disease assessments were done at 2, 4, and 6 months. For the purpose of the analysis (landmark method), disease response was subclassified in six categories: partial response (PR; > 30% size reduction), minor response (MR; 10% to 30% reduction), no change (NC) as either NC- (0% to 10% reduction) or NC+ (0% to 20% size increase), progressive disease (PD; > 20% increase/new lesions), and subjective PD (clinical progression). RESULTS: A total of 906 patients had measurable disease at entry. At all measurement time points, complete response (CR), PR, and MR resulted in similar TTP and OS; this was also true for NC- and NC+, and for PD and subjective PD. Patients were subsequently classified as responders (CR/PR/MR), NC (NC+/NC-), or PD. This three-class response categorization was found to be highly predictive of further progression or survival for the first two measurement points. After 6 months of imatinib, responders (CR/PR/MR) had the same survival prognosis as patients classified as NC. CONCLUSION: RECIST perfectly enables early discrimination between patients who benefited long term from imatinib and those who did not. After 6 months of imatinib, if the patient is not experiencing PD, the pattern of radiologic response by tumor size criteria has no prognostic value for further outcome. Imatinib needs to be continued as long as there is no progression according to RECIST.

KIT mutations and dose selection for imatinib in patients with advanced gastrointestinal stromal tumours.

A recent randomized EORTC phase III trial, comparing two doses of imatinib in patients with advanced gastrointestinal stromal tumours (GISTs), reported dose dependency for progression-free survival. The current analysis of that study aimed to assess if tumour mutational status correlates with clinical response to imatinib. Pre-treatment samples of GISTs from 377 patients enrolled in phase III study were analyzed for mutations of KIT or PDGFRA by combination of D-HPLC and direct sequencing of tumour genomic DNA. Mutation types were correlated with patients' survival data. The presence of exon 9-activating mutations in KIT was the strongest adverse prognostic factor for response to imatinib, increasing the relative risk of progression by 171% (P&lt;0.0001) and the relative risk of death by 190% (P&lt;0.0001) when compared with KIT exon 11 mutants. Similarly, the relative risk of progression was increased by 108% (P&lt;0.0001) and the relative risk of death by 76% (P=0.028) in patients without detectable KIT or PDGFRA mutations. In patients whose tumours expressed an exon 9 KIT oncoprotein, treatment with the high-dose regimen resulted in a significantly superior progression-free survival (P=0.0013), with a reduction of the relative risk of 61%. We conclude that tumour genotype is of major prognostic significance for progression-free survival and overall survival in patients treated with imatinib for advanced GISTs. Our findings suggest the need for differential treatment of patients with GISTs, with KIT exon 9 mutant patients benefiting the most from the 800 mg daily dose of the drug.

Nilotinib in the treatment of advanced gastrointestinal stromal tumours resistant to both imatinib and sunitinib.

Patients diagnosed with advanced gastrointestinal stromal tumours (GISTs) who are resistant or intolerant to both imatinib and second-line sunitinib have a poor prognosis and few therapeutic options. We evaluated the efficacy of nilotinib, a novel tyrosine kinase inhibitor (TKI) in patients pretreated with imatinib and sunitinib. Fifty-two consecutive patients treated with oral nilotinib, 400mg twice daily, within the nilotinib compassionate use programme in 12 European cancer centres, were included in this retrospective analysis. Median age was 59 years (range 24-80), and all patients had WHO performance score better than 3. All patients had failed both imatinib and sunitinib pretreatment, either due to progressing GIST (96%) or intolerance (4%). Five patients (10%; 95% confidence interval (CI) 2-18) responded to nilotinib and 19 patients (37%; 95% CI 24-50) achieved a disease stabilisation. Nilotinib was generally well tolerated, but six patients (12%) discontinued treatment due to intolerance. Median progression-free survival of nilotinib treatment was 12 weeks (95% CI 9-15; range 0-104) and median overall survival was 34 weeks (95% CI 3-65; range 2-135). Nilotinib is active in GIST resistant to both imatinib and sunitinib. These results warrant further investigation of nilotinib in GIST.