Financial Implications of Avapritinib for Treatment of Unresectable Gastrointestinal Stromal Tumors in Patients With a PDGFRA Exon 18 Variant or After 3 Previous Therapies in a Hypothetical US Health Plan.

Importance: With the approval of avapritinib for adults with unresectable or metastatic gastrointestinal stromal tumors (GISTs) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 variant, including PDGFRA D842V variants, and National Comprehensive Cancer Network guideline recommendations as an option for patients with GIST after third-line treatment, it is important to estimate the potential financial implications of avapritinib on a payer's budget. Objective: To estimate the budget impact associated with the introduction of avapritinib to a formulary for metastatic or unresectable GISTs in patients with a PDGFRA exon 18 variant or after 3 or more previous treatments from the perspective of a US health plan. Design, Setting, and Participants: For this economic evaluation, a 3-year budget impact model was developed in March 2020, incorporating costs for drug acquisition, testing, monitoring, adverse events, and postprogression treatment. The model assumed that avapritinib introduction would be associated with increased PDGFRA testing rates from the current 49% to 69%. The health plan population was assumed to be mixed 69% commercial, 22% Medicare, and 9% Medicaid. Base case assumptions included a GIST incidence rate of 9.6 diagnoses per million people, a metastatic PDGFRA exon 18 mutation rate of 1.9%, and progression rate from first-line to fourth-line treatment of 17%. Exposures: The model compared scenarios with and without avapritinib in a formulary. Main Outcomes and Measures: Annual, total, and per member per month (PMPM) budget impact. Results: In a hypothetical 1-million member plan, fewer than 0.1 new patients with a PDGFRA exon 18 variant per year and 1.2 patients receiving fourth-line therapy per year were eligible for treatment. With avapritinib available, the total increase in costs in year 3 for all eligible adult patients with a PDGFRA exon 18 variant was $46 875, or $0.004 PMPM. For patients undergoing fourth-line treatment, the total increase in costs in year 3 was $69 182, or $0.006 PMPM. The combined total budget impact in year 3 was $115 604, or $0.010 PMPM, including an offset of $3607 in postprogression costs avoided or delayed. The higher rates of molecular testing resulted in a minimal incremental testing cost of $453 in year 3. Conclusions and Relevance: These results suggest that adoption of avapritinib as a treatment option would have a minimal budget impact to a hypothetical US health plan. This would be primarily attributable to the small eligible patient population and cost offsets from reduced or delayed postprogression costs.

Phase I Study of Rapid Alternation of Sunitinib and Regorafenib for the Treatment of Tyrosine Kinase Inhibitor Refractory Gastrointestinal Stromal Tumors.

PURPOSE: Polyclonal emergence of KIT secondary mutations is a main mechanism of imatinib progression in gastrointestinal stromal tumor (GIST). Approved KIT inhibitors sunitinib and regorafenib have complementary activity against KIT resistance mutations. Preclinical evidence suggests that rapid alternation of sunitinib and regorafenib broadens the spectrum of imatinib-resistant subclones targeted. PATIENTS AND METHODS: Phase Ib study investigating continuous treatment with cycles of sunitinib (3 days) followed by regorafenib (4 days) in patients with tyrosine kinase inhibitor (TKI)-refractory GIST. A 3+3 dosing schema was utilized to determine the recommended phase II dose (RP2D). Plasma samples were analyzed for pharmacokinetics and circulating tumor DNA (ctDNA) studies using targeted error correction sequencing (TEC-seq) and droplet digital PCR (ddPCR). RESULTS: Of the 14 patients enrolled, 2 experienced dose-limiting toxicities at dose level 2 (asymptomatic grade 3 hypophosphatemia). Sunitinib 37.5 mg/day and regorafenib 120 mg/day was the RP2D. Treatment was well-tolerated and no unexpected toxicities resulted from the combination. Stable disease was the best response in 4 patients, and median progression-free survival was 1.9 months. Combined assessment of ctDNA with TEC-seq and ddPCR detected plasma mutations in 11 of 12 patients (92%). ctDNA studies showed that KIT secondary mutations remain the main mechanism of resistance in TKI-refractory GIST, revealing effective suppression of KIT-mutant subpopulations in patients benefiting from the combination. CONCLUSIONS: Sunitinib and regorafenib combination is feasible and tolerable. Rapid alternation of TKIs with complementary activity might be effective when combining drugs with favorable pharmacokinetics, potentially allowing active doses while minimizing adverse events. Serial monitoring with ctDNA may guide treatment in patients with GIST.

Predictive factors for toxicity and survival of second-line sunitinib in advanced gastrointestinal stromal tumours (GIST).

Introduction: Sunitinib is a standard second-line treatment in advanced gastrointestinal stromal tumours (GIST). We aimed to search for predictive factors for grade 3 and 4 toxicity, progression-free survival (PFS) and overall survival (OS) in a GIST reference center patient population, outside clinical trials.Methods: A retrospective analysis was performed of patients treated in two European Comprehensive Cancer Centers between January 2005 and December 2015. Demographic and clinical features, tumour characteristics and biological parameters were investigated. Logistic regression models were used to find factors associated with grade 3 and 4 toxicity. To identify predictive factors for PFS and OS, variables that were statistically significant in univariate analysis were used in the multivariate Cox proportional hazards model.Results: Ninety-one patients were included in this analysis. Age >60 years (HR 5.0, p = .006) and body weight ≤70 kg (HR 4.7, p = .009) were predictive factors for grade 3 and 4 toxicity. When divided into two categories, non-haematological grade 3 and 4 toxicity was predicted by age >60 years (HR 3.8, p = .012) and body weight ≤70 kg (HR 3.3, p = .025) whereas haematological toxicity had no significantly associated predictive factors. The median PFS and OS with sunitinib were 8.8 months and 27.5 months, respectively. The use of imatinib less than six months compared to 6-12 months (HR 0.2, p = .013) and to >12 months (HR 0.3, p = .016) and liver and/or peritoneal metastases (HR 0.1, p < .001, HR 0.2, p = .003 and HR 0.2, p = .004) compared to locally advanced disease only were predictive for longer PFS. High neutrophil (HR 3.1, p = 0.04) and platelet count (HR 2.4, p = .046) predicted a shorter OS. Flexible sunitinib dosing was associated with superior OS (p = .021).Conclusion: In advanced GIST patients treated with sunitinib, older and low-weight patients are at risk for grade 3 and 4 toxicity. Clinical (prior imatinib use and metastases), biological (neutrophil and platelet count) and treatment characteristics independently predict PFS and OS.

Real-World Evidence of Patient Outcome Following Treatment of Advanced Gastrointestinal Stromal Tumor (GIST) with Imatinib, Sunitinib, and Sorafenib in Publicly Funded Health Care in Poland.

BACKGROUND This study aimed to undertake an analysis of ten years of real-world evidence (RWE) on overall survival (OS) following treatment of advanced gastrointestinal stromal tumor (GIST) with imatinib, sunitinib, and sorafenib using data from the Polish National Health Fund. MATERIAL AND METHODS Data from the Polish National Health Fund, the sole Polish public payer, identified 1,641 patients with advanced GIST who were treated with imatinib (n=1047), sunitinib (n=457), and sorafenib (n=137). The differences in overall survival (OS) were analyzed. RESULTS For patients with advanced GIST, the median follow-up time for patients treated with imatinib was 71 months (95% CI, 64.8-79.2), the median OS was 56.9 months (95% CI, 50.4-61.2), with survival at 12 months (89.5%), 24 months (77.9%), 36 months (66.9%), and 60 months (48.4%). The median follow-up time for patients treated with sunitinib was 41.4 months (95% CI, 34.6-49.3), the median OS was 22.8 months (95% CI, 19.2-26.8), with survival at 12 months (68.2%), 24 months (47.1%), and 36 months (31%). The median follow-up time for patients treated with sorafenib was 17.4 months (95% CI, 14.6-22.9), the median OS was 16.9 months (95% CI, 13.7-24.3), with survival at 12 months (61.9%), at 24 months (36.2%), and at 36 months (16.8%). CONCLUSIONS Real-world data collected in a ten-year period confirmed the effectiveness of the use of imatinib, sunitinib, or sorafenib for the treatment of advanced GIST and was comparable with the findings from clinical trials.

Discovery of Conformational Control Inhibitors Switching off the Activated c-KIT and Targeting a Broad Range of Clinically Relevant c-KIT Mutants.

Drug resistance due to acquired mutations that constitutively activate c-KIT is a significant challenge in the treatment of patients with gastrointestinal stromal tumors (GISTs). Herein, we identified 1-(5-ethyl-isoxazol-3-yl)-3-(4-{2-[6-(4-ethylpiperazin-1-yl)pyrimidin-4-ylamino]-thiazol-5-yl}phenyl)urea (10a) as a potent inhibitor against unactivated and activated c-KIT. The binding of 10a induced rearrangements of the DFG motif, αC-helix, juxtamembrane domain, and the activation loop to switch the activated c-KIT back to its structurally inactive state. To the best of our knowledge, it is the first structural evidence demonstrating how a compound can inhibit the activated c-KIT by switching back to its inactive state through a sequence of conformational changes. Moreover, 10a can effectively inhibit various c-KIT mutants and the proliferation of several GIST cell lines. The distinct binding features and superior inhibitory potency of 10a, together with its excellent efficacy in the xenograft model, establish 10a as worthy of further clinical evaluation in the advanced GISTs.

Mutational Testing in Gastrointestinal Stromal Tumor.

Targeted treatment has become a major modality in cancer management. Such cancer drugs are generally designed to treat tumors with certain genetic/genomic makeups. Mutational testing prior to prescribing targeted therapy is crucial in identifying who can receive clinical benefit from specific cancer drugs. Over the last two decades, gastrointestinal stromal tumors (GISTs) have evolved from histogenetically obscure to being identified as distinct gastrointestinal mesenchymal tumors with well-defined clinical and molecular characteristics, for which multiple lines of targeted therapies are available. Although the National Comprehensive Cancer Network (NCCN) strongly recommends mutational testing for optimal management of GIST, many GIST patients still have neither a mutation test performed or any mutation-guided cancer management. Here, we review the mutation-guided landscape of GIST, mutational testing methods, and the recent development of new therapies targeting GIST with specific mutations.

PLX9486 shows anti-tumor efficacy in patient-derived, tyrosine kinase inhibitor-resistant KIT-mutant xenograft models of gastrointestinal stromal tumors.

The purpose of the present study was to investigate the in vitro and in vivo activity of PLX9486, a tyrosine kinase inhibitor (TKI) targeting both primary KIT exon 9 and 11 and secondary exon 17 and 18 mutations in gastrointestinal stromal tumors (GISTs). Imatinib, a potent inhibitor of mutated KIT, has revolutionized the clinical management of advanced, metastatic GIST. However, secondary resistance develops mainly through acquired mutations in KIT exons 13/14 or exons 17/18. Second-line sunitinib potently inhibits KIT exon 13/14 mutants but is ineffective against exon 17 mutations. In our study, PLX9486 demonstrated in vitro nanomolar potency in inhibiting the growth and KIT phosphorylation of engineered BaF3 cells transformed with KIT exon 17 mutations (p.D816V) and with the double KIT exon 11/17 mutations (p.V560G/D816V). The in vivo efficacy of PLX9486 was evaluated using two imatinib-resistant GIST patient-derived xenograft (PDX) models. In UZLX-GIST9 (KIT: p.P577del;W557LfsX5;D820G), PLX9486 100 mg/kg/day resulted in significant inhibition of proliferation. Pharmacodynamic analysis showed a pronounced reduction in mitogen-activated protein kinase (MAPK) activation and other downstream effects of the KIT signaling pathway but no significant effect on KIT Y703 and Y719 phosphorylation. Similarly, in MRL-GIST1 (KIT: p.W557_K558del;Y823D) PLX9486 treatment led to significant tumor regression and strong inhibition of MAPK activation. Interestingly, the inhibitory effect on MAPK activation was evident even after a single dose of PLX9486. In conclusion, PLX9486 showed anti-tumor efficacy in patient-derived imatinib-resistant GIST xenograft models, mainly through inhibition of KIT signaling. These preclinical efficacy data encourage further testing of PLX9486 in the clinical setting.

Adverse reactions of sorafenib, sunitinib, and imatinib in treating digestive system tumors.

BACKGROUND: This study was conducted to assess the adverse reactions caused by multi-target tyrosine kinase inhibitor treatment of gastrointestinal tumors. METHODS: We carried out a retrospective study of drug-related adverse reactions in 115 patients who were treated with sorafenib, sunitinib, and imatinib for primary hepatocellular carcinoma or gastrointestinal stromal tumors from October 2003 to March 2012 at the Peking University International Hospital. RESULTS: The total incidence of adverse reactions of sorafenib, sunitinib, and imatinib in patients with hepatocellular carcinoma and gastrointestinal stromal tumors was > 80%. The main adverse reactions of sorafenib were hypertension in 38 patients (33.3%) and diarrhea in 28 patients (24.4%). Sunitinib was associated with higher incidence and greater grade 3-4 toxicity. The common toxicities were skin color changes in 105 patients (90.9%), hand-foot skin reactions in 65 patients (54.6%), and leukopenia (63.6%), hypertension (22.7%), proteinuria (22.7%), liver function impairment (22.7%), and hypomagnesemia (27.3%). While imatinib was well tolerated, it was associated with the highest number of adverse reactions, including skin color change (55.6%) and edema (38.9%). Hypophosphatemia (4.4%) and hoarseness (2.2%) only occurred in the sorafenib treatment group. CONCLUSIONS: The adverse reactions of multi-target tyrosine kinase inhibitor treatments are generally mild to moderate, and most patients can tolerate these without the need for further intervention. Some serious adverse reactions may be alleviated by discontinuing the drugs or by administering symptomatic treatment.

Cytoreductive Surgery for Metastatic Gastrointestinal Stromal Tumors Treated With Tyrosine Kinase Inhibitors: A 2-institutional Analysis.

OBJECTIVE: To refine treatment recommendations for patients with metastatic gastrointestinal stromal tumors (GISTs) treated with tyrosine kinase inhibitors (TKIs) and surgery. BACKGROUND: Early reports suggested that patients with metastatic GIST responding to TKIs treated with surgery may have favorable outcomes. However, identification of prognostic factors was limited by small cohorts. METHODS: Progression-free survival (PFS) and overall survival (OS) from time of surgery and from start of initial TKI was determined. Multivariate analysis was conducted on all patients undergoing GIST metastasectomy between 2001 and 2014 at 2 institutions. RESULTS: We performed 400 operations on 323 patients with metastatic GIST on TKIs. Radiographic response at time of surgery was classified as responsive disease (RD, n = 64, 16%), stable disease (SD, n = 100, 25%), unifocal progressive disease (UPD, n = 132, 33%), and multifocal progressive disease (MPD, n = 104, 26%). For patients on imatinib before surgery, radiographic response was predictive of PFS from time of surgery (RD 36 months, SD 30 months, UPD 11 months, MPD 6 months; P < 0.001) and from imatinib initiation (RD 71 months, SD 51 months, UPD 47 months, MPD 33 months; P < 0.001). Radiographic response was predictive of OS from time of surgery (RD not reached, SD 110 months, UPD 59 months, MPD 24 months; P < 0.001), and from imatinib initiation (RD not reached, SD 144 months, UPD 105 months, MPD 66 months; P = 0.005). Radiographic response was not predictive of PFS/OS for patients on sunitinib. Metastatic mitotic index ≥5/50 HPF, MPD, and R2 resection were prognostic of worse PFS/OS; primary mutation was not. CONCLUSIONS: Surgery in metastatic GIST patients in the absence of MPD on imatinib is associated with outcomes at least comparable with second-line sunitinib and may be considered in select patients.

Can laparoscopic surgery be applied in gastric gastrointestinal stromal tumors located in unfavorable sites?: A study based on the NCCN guidelines.

This article investigated the feasibility of laparoscopic surgery in unfavorable site gastric gastrointestinal stromal tumors (GISTs).We identified 214 patients who underwent primary gastric GIST resection at our institution (January 2006-December 2014) from a prospectively collected database. These patients were divided into a Favorable group (140 cases) and an Unfavorable group (74 cases) according to the 2014 version of the National Comprehensive Cancer Network Clinical Guidelines (NCCN guidelines).The wedge resection rate of the Favorable group was higher than that of the Unfavorable group, and most procedures were performed laparoscopically (P < 0.05). In addition, there were no differences in the other clinicopathological features between these groups (P > 0.05). The postoperative stay of the Unfavorable group was longer than that of the Favorable group (P = 0.02). Laparoscopic surgery in both groups resulted in a shorter operative time, lower blood loss, faster time to first flatus, faster time to first fluid diet, and shorter postoperative stay than open surgery (P < 0.05). Although the difference was not significant (P = 0.09), the postoperative complication incidence of the Favorable group was less than that of the Unfavorable group (10% vs 17.6%). Furthermore, in the Unfavorable group, the incidence of postoperative complications from laparoscopic surgery was significantly lower than that of open surgery (P = 0.001). There were no differences in the 5-year overall survival (OS) and recurrence-free survival (RFS) of these groups (P > 0.05). Furthermore, in the Unfavorable group, the 5-year OS and RFS were similar for both laparoscopic and open procedures. Multivariate Cox regression analysis showed that imatinib (IM) treatment was an independent risk factor for poor prognosis.Laparoscopic operation for gastric GISTs located in unfavorable sites can yield similar long-term outcomes compared with an open operation. However, laparoscopic surgery has the obvious advantage of being minimally invasive, and the incidence of postoperative complications was low. Laparoscopic surgery is thus an option for the treatment of localized gastric GISTs.

Laparoscopic Versus Open Resection for Gastrointestinal Stromal Tumors (GISTs).

PURPOSE: Primary gastrointestinal stromal tumors (GISTs) are typically treated with open resection. There is growing interest in laparoscopic GIST resection; however, data is limited. We report our experience with GIST resections using both open and laparoscopic techniques. MATERIALS AND METHODS: Twenty-nine GIST patients underwent definitive intent resection at the University of Missouri from 1990 to 2010. Patients who underwent laparoscopic resection (n = 7) were matched on the basis of tumor size, age, tumor location, and National Comprehensive Cancer Network (NCCN) risk stratification with seven patients who underwent open resection. The two groups were compared with respect to age, gender, BMI, tumor size, tumor site, mitotic rate, surgical margins, NCCN risk stratification, estimated blood loss, hospital stay, surgical complications, disease recurrence, and overall survival. RESULTS: The cohorts did not differ with respect to age, gender, BMI, tumor location, tumor size, or positive margins (p > 0.05). Patients who underwent open resection had more NCCN high-risk patients, but the difference was not statistically significant (p = 0.08). There was significantly less estimated blood loss (median 15 vs. 150 mL, p < 0.05) and significantly shorter hospital stay (median 4 vs. 7 days, p < 0.05) for the laparoscopy group. There were no recurrences in the laparoscopy group, but there was one in the open group with a median follow-up of 55 and 63 months, respectively (p > 0.05). Five-year disease-free survival was 100 % for the laparoscopic group and 83 % for the open resection group. CONCLUSIONS: Laparoscopic resection for appropriately selected GISTs is feasible and associated with significantly less blood loss and shorter hospitalizations compared to open resection. Further studies are needed to better define its role for GIST.

Combination of Imatinib Mesylate and AKT Inhibitor Provides Synergistic Effects in Preclinical Study of Gastrointestinal Stromal Tumor.

PURPOSE: Gastrointestinal stromal tumors (GIST) generally harbor activating mutations in the receptor tyrosine kinase KIT or in the related platelet-derived growth factor receptor alpha (PDGFRA). GIST treated with imatinib mesylate or second-line therapies that target mutant forms of these receptors generally escape disease control and progress over time. Inhibiting additional molecular targets may provide more substantial disease control. Recent studies have implicated the PI3K/AKT pathway in the survival of imatinib mesylate-resistant GIST cell lines and tumors. EXPERIMENTAL DESIGN: Here, we performed in vitro and in vivo studies evaluating the novel combination of imatinib mesylate with the AKT inhibitor MK-2206 in GIST. Whole-transcriptome sequencing (WTS) of xenografts was performed to explore the molecular aspects of tumor response to this novel combination and to potentially identify additional therapeutic targets in GIST. RESULTS: This drug combination demonstrated significant synergistic effects in a panel of imatinib mesylate-sensitive and -resistant GIST cell lines. Furthermore, combination therapy provided significantly greater efficacy, as measured by tumor response and animal survival, in imatinib mesylate-sensitive GIST xenografts as compared with treatment with imatinib mesylate or MK-2206 alone. WTS implicated two neural genes, brain expressed X-linked 1 and neuronal pentraxin I, whose expression was significantly upregulated in combination-treated tumors compared with tumors treated with the two monotherapies. CONCLUSIONS: These studies provide strong preclinical justification for combining imatinib mesylate with an AKT inhibitor as a front-line therapy in GIST. In addition, the WTS implicated the BCL-2/BAX/BAD apoptotic pathway as a potential mechanism for this enhanced combination effect. Clin Cancer Res; 23(1); 171-80. ©2016 AACR.

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.

Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.

BACKGROUND: Gastrointestinal stromal tumours (GIST) are the most common mesenchymal neoplasms of the gastrointestinal tract. Imatinib followed by sunitinib and regorafenib is the standard sequence of treatment for advanced disease. Pazopanib is effective in soft tissue sarcomas but has never been assessed in advanced GIST in a randomised trial. We aimed to assess the efficacy and safety of pazopanib in patients with previously treated advanced GIST. METHODS: In this randomised, open-label phase 2 study, we enrolled adults (aged ≥18 years) with advanced GIST resistant to imatinib and sunitinib from 12 comprehensive cancer centres or university hospitals in France and randomly assigned them 1:1 using an interactive web-based centralised platform to 800 mg oral pazopanib once daily in 4-week cycles plus best supportive care or best supportive care alone. Randomisation was stratified by the number of previous treatment regimens (2 vs ≥3); no-one was masked to treatment group allocation. Upon disease progression, patients in the best supportive care group were allowed to switch to pazopanib as compassionate treatment. The primary endpoint was investigator-assessed progression-free survival, analysed by intention-to-treat. All randomised participants who received at least one dose of pazopanib were included in the safety analysis. This study is registered with ClinicalTrials.gov, number NCT01323400. FINDINGS: Between April 12, 2011, and Dec 9, 2013, 81 patients were enrolled and randomly assigned to pazopanib plus best supportive care (n=40) or best supportive care alone (n=41). The median follow-up was 26·4 months (IQR 22·0-37·8) in the pazopanib plus best supportive care group and 28·9 months (22·0-35·2) in the best supportive care group. 4-month investigator-assessed progression-free survival was 45·2% (95% CI 29·1-60·0) in the pazopanib plus best supportive care group versus 17·6% (7·8-30·8) in the best supportive care group (hazard ratio [HR] 0·59, 95% CI 0·37-0·96; p=0·029). Median progression-free survival was 3·4 months (95% CI 2·4-5·6) with pazopanib plus best supportive care and 2·3 months (2·1-3·3) with best supportive care alone (HR 0·59 [0·37-0·96], p=0·03). 36 (88%) of the patients originally assigned to the best supportive care group switched to pazopanib following investigator-assessed disease progression; these patients had a median progression-free survival from pazopanib initiation of 3·5 months (95% CI 2·2-5·2). 55 (72%) of the 76 pazopanib-treated patients had pazopanib-related grade 3 or worse adverse events, the most common of which was hypertension (15 [38%] in the pazopanib plus best supportive care group and 13 [36%] in the best supportive care group). 20 (26%) patients had pazopanib-related serious adverse events (14 [35%] in the pazopanib plus best supportive care group and six [17%] in the best supportive care group), including pulmonary embolism in eight (9%) patients (five [13%] in the pazopanib plus best supportive care group and three [7%] in the best supportive care group). Three pazopanib-related deaths occurred (two pulmonary embolisms [one in each group] and one hepatic cytolysis [in the best supportive care group]). Three adverse event-related but not pazopanib-related deaths occurred in the best supportive care group after switch to pazopanib; these deaths were from hyperammonaemic encephalopathy, pneumopathy, and respiratory failure. INTERPRETATION: Pazopanib plus best supportive care improves progression-free survival compared with best supportive care alone in patients with advanced GIST resistant to imatinib and sunitinib, with a toxicity profile similar to that reported for other sarcomas. This trial provides reference outcome data for future studies of targeted inhibitors in the third-line setting for these patients. FUNDING: GlaxoSmithKline, French National Cancer Institute, EuroSARC (FP7-278742), Centre Léon Bérard.

Molecular cytology genotyping of primary and metastatic GI stromal tumors by using a custom two-gene targeted next-generation sequencing panel with therapeutic intent.

BACKGROUND AND AIMS: In an era of precision medicine, customized genotyping of GI stromal tumors by screening for driver mutations will become the standard of care. The fidelity of genotype concordance between paired cytology smears and surgical pathology specimens is unknown. In patients with either primary or metastatic sporadic disease, we sought to determine the frequency of KIT and PDGFRA pathogenic alterations within such specimens, imatinib sensitivity, and the concordance of pathogenic alterations between paired specimens. METHODS: DNA obtained from cytology smears from 36 patients, 24 of whom had paired surgical pathology specimens, underwent targeted next-generation sequencing by using a custom panel to evaluate somatic mutations within KIT (exon 2, 9, 10, 11, 13, 14, 15, 17, 18) and PDGFRA (exon 12, 14, 15, 18) genes. Patients with KIT and PDGRFA wild-type genes completed the Qiagen Human Comprehensive Cancer GeneRead DNAseq Targeted Array V2. RESULTS: Genotyping revealed KIT and PDGFRA mutations in 68% and 15% of patients. The wild-type population did not harbor mutations in BRAF, RAS family, SDHB, SETD2, or NF1. Imatinib sensitivity based on the oncogenic kinase mutation prevalence was estimated to be 68%. Mutational concordance between paired cytology and surgical pathology specimens was 96%. CONCLUSIONS: Our data have demonstrated the ability to stratify either primary or metastatic gastrointestinal stromal tumors by mutational subtype using a targeted next-generation sequencing 2 gene mutation panel. We highlight the ability to use cytology specimens obtained via minimally invasive techniques as a surrogate to surgical specimens given the high mutational landscape concordance between paired specimens.

Tumores del estroma gastrointestinal: revisión de nuestra experiencia / Surgery of gastrointestinal stromal tumors: review of our experience in the last five years

Objective: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Surgical resection is the standard treatment for localized primary GISTs. The aim of the study is to present our 5-year surgical experience, as well as the results obtained in terms of survival and disease progression. Material and Method: We conducted a descriptive, retrospective study of primary GISTs treated in our center between 2009-2013. We analyze the most relevant variables, criteria of risk of progression according Fletcher's classification from National Institutes of Health and the Miettinem's classification from the Armed Forces Institute of Pathology, as well as analysis of relapse-free survival (RFS) with Kaplan-Meier survival curves. Results: We present a series of 30 patients. Mean age 65 years (40-84 years). The most common location was the stomach (n = 14, 46.6 percent). The surgery was R0 in 23 cases of 30. The mean tumor diameter was 5.3 cm (0.5-18). 14 patients received adjuvant treatment with Imatinib. After an average follow-up of 31.2 months (6-62 months), it was found relapse in 4 patients, progression and exitus in 1, exitus in 3 and exitus in the immediate postoperative period in 1. RFS at one year was 96.7 percent, and 89.2 percent at 4 years. Mean survival time was 56.2 months (95 percent CI 51.8-60.6). Conclusion: The recommended attitude after radical surgery is follow-up. In selected patients with risk of relapse, adjuvant treatment with Imatinib delays the progression of the disease and increases the survival.

Objetivo: Los tumores del estroma gastrointestinal son las neoplasias mesenquimales más frecuentes del tubo digestivo. La resección quirúrgica es el tratamiento estándar en los GISTs primarios localizados. El objetivo del estudio es presentar nuestra experiencia quirúrgica en 5 años, así como los resultados obtenidos en cuanto supervivencia y progresión de la enfermedad. Material y Método: Serie de casos, estudio observacional descriptivo retrospectivo, que analiza los resultados obtenidos en cuanto al tratamiento quirúrgico de GIST primarios sometidos a resección quirúrgica en nuestro centro entre 2009-2013. Todas las intervenciones fueron realizadas por personal del Staff y dentro de los protocolos de las unidades de cirugía hepato-biliar y esófago-gástrica. Se analizan las variables de mayor relevancia, criterios de riesgo de progresión según la clasificación de Fletcher del National Institutes of Health y la clasificación de Miettinem del Armed Forces Institute of Pathology, así como análisis de la supervivencia libre de recaída (SLR) con curvas de Kaplan-Meier. Resultados: Presentamos una serie de 30 pacientes. Edad media de 65 años (40-84 años). La localización más frecuente fue estómago (n = 14, 46,6 por ciento). La cirugía fue R0 en 23 de los 30 pacientes. El diámetro tumoral medio fue de 5,3 cm (0,5-18, con una mediana de 4 cm. Catorce pacientes recibieron tratamiento adyuvante con Imatinib. Tras un seguimiento medio 31,2 meses (6-62 meses), se detectó recaída en 4 pacientes, progresión y exitus en 1, exitus en 3 y exitus en el postoperatorio inmediato en 1. La SLR al año fue del 96,7 por ciento, siendo del 89,2 por ciento a los 4 años. El tiempo medio de supervivencia fue de 56,2 meses (IC 95 por ciento 51,8-60,6). Conclusiones: La actitud recomendada tras una cirugía radical es el seguimiento. En pacientes seleccionados con riesgo de recaída el tratamiento adyuvante con Imatinib retrasa la progresión de la enfermedad y aumenta la supervivencia.

Clinical Observations on Treatment for Chinese Patients with Gastrointestinal Stromal Tumors.

BACKGROUND: To investigate the diagnostic and treatment methods for Chinese patients with gastrointestinal stromal tumor (GIST). MATERIALS AND METHODS: From January 2004 to June 2014, patients diagnosed with primary GIST and treated by a single medical team in the Department of Digestive Disease of XuYi Hospital of Traditional Chinese Medicine were retrospectively recruited. Re-examination and follow-up was conducted regularly and abdominal enhanced CT, blood biochemistry and responses to surgery or imatinib were recorded. RESULTS: A total of 15 patients were enrolled, including 9 male and 6 female patients, with an average age of 54 years (ranging from 32-81 years). The primary symptoms were abdominal uncomfortable in 5 patients, abdominal pain in 6 patients as well as nausea and vomiting in 4 patients. One patient was diagnosed with bowl obstruction at the first visit. All patients were treated with surgery, and tumor site was confirmed 1 esophagus, 6 stomach, 4 small bowel, and 4 colorectal and all patients were pathologically diagnosed with GIST. Immunochemical test positive for CD 117 was found 12 patients, and positive for CD 34 in7 patients. The median follow-up time was 24 months (range of 3-63). Three metastasis were confirmed 1.5, 2 and 2.6 years postoperatively. Three patients were treatment by imatinib postoperatively. CONCLUSIONS: Surgery remains the main treatment method for Chinese patients with GIST and imatinib could be feasible and safe for treating Chinese patients with GIST.

Regorafenib: A novel tyrosine kinase inhibitor: A brief review of its therapeutic potential in the treatment of metastatic colorectal carcinoma and advanced gastrointestinal stromal tumors.

Regorafenib is a novel oral multitargeted tyrosine kinase inhibitor having both antitumor and anti-angiogenic activities. Regorafenib was recently approved by US Food and Drug Administration in February 25, 2013 in the treatment for patients with advanced gastrointestinal stromal tumor and for the treatment of patients with metastatic colorectal carcinoma after disease progression or intolerance to imatinib mesylate and sunitinib therapy. Oral regorafenib demonstrates a high level of efficacy with acceptable tolerability with the 160 mg daily for 3 weeks followed by 1 week off schedule; a continuous schedule could be of interest. Hypertension, mucositis, hand foot skin reaction, diarrhea and asthenia are the most common side-effects. Regardless of these encouraging results, studies investigating, adjuvant and neoadjuvant settings are awaited, as well as trials using regorafenib in combination with chemotherapy or other targeted therapies. Clinical trials investigating regorafenib in other tumor types are ongoing.

Clinical and therapeutic considerations of GIST.

Gastrointestinal stromal tumors (GIST) are rare tumors of the digestive tract, with an incidence of about 1.5 per 100,000/year. Clinical features may vary depending on location, size and aggressiveness. The diagnosis is confirmed by immunohistochemistry tests that identify CD 117 or DOG1 (typical receptors/markers for most GISTs) at the level of biopsy specimen. The treatment of localized GIST is based primarily on the surgery, while for metastatic GIST the targeted therapy with tyrosine kinase inhibitors represents the current standard. The neoadjuvant and adjuvant therapy indications guided and depending on genetic analysis included in the diagnostic and treatment algorithm as well as the strategy for cases surveillance are listed in the journal. All these data obtained from the literature have been integrated in a practical experience of 19 cases of GIST, operated in the clinic in the last 10 years for which we have proposed an adapted diagnostic algorithm.

Analysis of prognostic factors impacting oncologic outcomes after neoadjuvant tyrosine kinase inhibitor therapy for gastrointestinal stromal tumors.

BACKGROUND: Management of gastrointestinal stromal tumors (GISTs) has been transformed with tyrosine kinase inhibitors (TKIs). While data on optimal duration of adjuvant imatinib remains elusive, guidelines for administration of neoadjuvant TKIs remain unknown. METHODS: Under an institutional review board-approved protocol, patients at our institution with a diagnosis of GIST treated with neoadjuvant TKIs and surgical resection were identified. Clinical and pathologic characteristics were obtained from medical records. RESULTS: Ninety-three patients underwent surgical resection after neoadjuvant TKI therapy; 41 had primary and 52 had recurrent/metastatic GIST. Median follow-up was 2.4 years. Median duration of neoadjuvant therapy was 315 (range 3-1,611) days for primary and 537 (range 4-3,257) days for recurrent/metastatic GIST (p = 0.001). Two-year, recurrence-free survival (RFS) was 85 and 44 % for primary and recurrent/metastatic disease, respectively, whereas 2-year overall survival (OS) was 97 % for primary and 73 % for recurrent/metastatic GIST. For primary GIST, duration of neoadjuvant therapy >365 days (p = 0.02) was associated with higher risk of recurrence on univariate analysis, whereas none of the clinicopathologic factors impacted OS. For recurrent/metastatic disease, disease progression was associated with a shorter OS (p = 0.001), but no factors were found to impact RFS. Lastly, when examining all patients, KIT mutations (p = 0.03) and multivisceral resection (p = 0.011) predicted shorter RFS. CONCLUSIONS: Neoadjuvant TKIs can be effectively used for the treatment of primary and recurrent/metastatic GIST. While duration of neoadjuvant therapy, KIT mutation status, and the need for multivisceral resection can help to predict higher risk for recurrence, progression on neoadjuvant TKIs can aid in selection of patients with recurrent/metastatic disease for surgical resection.