Imatinib Mesylate for Patients with Recurrent or Metastatic Gastrointestinal Stromal Tumors Expressing KIT: A Decade Experience from Taiwan

PURPOSE: Our preliminary report of imatinib mesylate (IM) in gastrointestinal stromal tumor (GIST) patients detailed a high response rate; however, the long-term result is still unknown. We conducted an analysis of Taiwan advanced inoperable/metastatic GIST patients treated on IM regarding survival, pattern of failure, potential prognostic factors, and mutational status. PATIENTS AND METHODS: From 2001 to 2010, patients with pathologically proven advanced inoperable/metastatic GIST receiving IM were enrolled onto this study. Data on KIT mutational status, measurable tumor size, and other potential prognostic factors were prospectively collected. Patients were followed up for a median of 33.6 months. RESULTS: There were 171 patients (106 men and 65 women) with response rate, and their clinical benefit for IM was 57.3% and 87.1%, respectively. Median progression-free survival (PFS) and overall survival (OS) for these 171 patients are 37.6 and 71.0 months, respectively. Of 171 patients, 120 (70.2%) remained on long-term IM use. Poor performance status, tumor larger than 11.5 cm, primary resistance, and the presence of an exon 9 mutation were independently associated with unfavorable PFS. Regarding OS, poor performance status, primary resistance, and tumor larger than 11.5 cm were three independently unfavorable predictors. CONCLUSIONS: The median PFS and OS of 171 GIST patients are 37.6 and 71.0 months, respectively. Poor performance status, tumor size larger than 11.5 cm, primary resistance, and an exon 9 mutation were independently associated with unfavorable PFS. Regarding OS, poor performance status, primary resistance, and tumor size larger than 11.5 cm were three independent unfavorable predictors.     

50例胃肠道间质瘤的临床病理分析

目的：探讨胃肠道间质瘤（GIST）的组织形态学特征及对该类肿瘤的诊断及预后问题。方法：对发生于2001年4月至2010年4月间的50例GIST进行临床病理及免疫组化分析。结果：50例GIST免疫组化检查结果,肿瘤均不表达CK而表达为Vimentin;CD117阳性表达43例,CD34阳性表达38例;S100均有不同程度表达,SMA阳性表达22例,Desmin阳性表达15例;Ki-67均有表达,其阳性度从＋．＋＋不等。结论：本组肿瘤中所有病例均不同程度表达Ki-67和PCNA,高危险性的阳性表达强、低危险性的阳性表达弱。这说明GIST的预后除与肿瘤的大小、组织形态学的改变及肿瘤的发生部位有关外,还与Ki-67和PCNA在肿瘤中的表达程度有关。     

GSTT1 Copy Number Gain and ZNF Overexpression Are Predictors of Poor Response to Imatinib in Gastrointestinal Stromal Tumors

Oncogenic mutations in gastrointestinal stromal tumors (GISTs) predict prognosis and therapeutic responses to imatinib. In wild-type GISTs, the tumor-initiating events are still unknown, and wild-type GISTs are resistant to imatinib therapy. We performed an association study between copy number alterations (CNAs) identified from array CGH and gene expression analyses results for four wild-type GISTs and an imatinib-resistant PDGFRA D842V mutant GIST, and compared the results to those obtained from 27 GISTs with KIT mutations. All wild-type GISTs had multiple CNAs, and CNAs in 1p and 22q that harbor the SDHB and GSTT1 genes, respectively, correlated well with expression levels of these genes. mRNA expression levels of all SDH gene subunits were significantly lower (P≤0.041), whereas mRNA expression levels of VEGF (P=0.025), IGF1R (P=0.026), and ZNFs (P<0.05) were significantly higher in GISTs with wild-type/PDGFRA D842V mutations than GISTs with KIT mutations. qRT-PCR validation of the GSTT1 results in this cohort and 11 additional malignant GISTs showed a significant increase in the frequency of GSTT1 CN gain and increased mRNA expression of GSTT1 in wild-type/PDGFRA D842V GISTs than KIT-mutant GISTs (P=0.033). Surprisingly, all four malignant GISTs with KIT exon 11 deletion mutations with primary resistance to imatinib had an increased GSTT1 CN and mRNA expression level of GSTT1. Increased mRNA expression of GSTT1 and ZNF could be predictors of a poor response to imatinib. Our integrative approach reveals that for patients with wild-type (or imatinib-resistant) GISTs, attempts to target VEGFRs and IGF1R may be reasonable options.     

胃肠道间质瘤临床诊治-附46例临床分析

目的:探讨胃肠间质瘤(Gastrointestinal Stromal Tumor,GIST)的临床特点及诊断及治疗方法。方法:回顾性分析我院1997-2009年收治的46例有完整病历资料的GIST病例,以探讨GIST的主要发生部位、临床表现、诊断和治疗方法。结果:GIST主要发生在胃(60.87%)和小肠(26.09%);主要表现为消化道出血(71.74%),腹痛不适(19.57%),腹部包块(15.22%)等;诊断首选B超(阳性率45.65%)、CT(阳性率100%)和内窥镜检查(阳性率81.09%)。本组手术45例,根治性切除40例,姑息性切除3例,术中活检1例,局部切除1例,1例放弃治疗。所有病例均经病理证实。随访42例,复发死亡11例,带瘤生存8例,无瘤生存21例,3例术后口服格列卫(甲磺伊马替尼,ST1571)的病人已生存8月、14月、18月。结论:目前GIST的治疗仍以手术治疗为主,分子靶向制剂的应用显示了一定的治疗效果。     

Comparison of Endoscopic and Open Resection for Small Gastric Gastrointestinal Stromal Tumor

The National Comprehensive Cancer Network recommends conservative follow-up for gastric gastrointestinal stromal tumors (GISTs) less than 2 cm. We have previously reported that the mitotic index of 22.22% of small gastric GISTs exceeded 5 per 50 high-power fields and recommended that all small gastric GISTs should be resected once diagnosed. The aim of the present study is to compare the safety and outcomes of endoscopic and open resection of small gastric GISTs. From May 2010 to March 2014, a total of 90 small gastric GIST patients were enrolled in the present study, including 40 patients who underwent surgical resection and 50 patients who underwent endoscopic resection. The clinicopathological characteristics, resection-related factors, and clinical outcomes were recorded and analyzed. The clinicopathological characteristics were comparable between the two groups except for tumor location and DOG-1 expression. Compared with the surgical resection group, the operation time was shorter (P = .000), blood loss was less (P = .000), pain intensity was lower (P < .05), duration of first flatus and defecation was shorter (P < .05), and medical cost of hospitalization was lower (P = .027) in the endoscopic resection group. The complications and postoperative hospital stay were comparable between the two groups. No in situ recurrence or liver metastasis was observed during follow-up. Endoscopic resection of small gastric GISTs is safe and feasible compared with surgical resection, although perforation could not be totally avoided during and after resection. The clinical outcome of endoscopic resection is also favorable.     

Practical Role of Mutation Analysis for Imatinib Treatment in Patients With Advanced Gastrointestinal Stromal Tumors: A Meta-Analysis

Background

Imatinib has become the standard first line treatment of gastrointestinal stromal tumors (GIST) in the advanced phase and adjuvant setting. We carried out an up-to-date meta-analysis to determine the practical role of mutation analysis for imatinib treatment in patients with advanced GIST.

Methods

Eligible studies were limited to imatinib treatment for patients with advanced GIST and reported on mutation analysis. Statistical analyses were conducted to calculate the odds ratio (OR), hazard ratio (HR) and 95% confidence interval (CI) using fixed-effects and random-effects models.

Results

A total of 2834 patients from 3 randomized controlled trials and 12 cohort studies were included. The ORs of response rates in KIT exon 11-mutant GISTs were 3.504 (95% CI 2.549-4.816, p<0.001) and 3.521 (95% CI 1.731-7.165, p=0.001) compared with KIT exon 9-mutant and wild type GISTs, respectively. The HRs of progression-free survival in KIT exon 11-mutant GISTs were 0.365 (95% CI 0.301-0.444, p<0.001) and 0.375 (95% CI 0.270-0.519, p<0.001) compared with KIT exon 9-mutant and wild type GISTs. The HRs of overall survival in KIT exon 11-mutant GISTs were 0.388 (95% CI 0.293-0.515, p<0.001) and 0.400 (95% CI 0.297-0.538, p<0.001) compared with KIT exon 9-mutant and wild type GISTs. No statistical significant differences were found between KIT exon 9-mutant and wild type. The overall response rate in KIT-exon 11-mutant GISTs were 70.5% (65%-75.9%) compared with 57.1% (51%-63.2%) in KIT-positive GISTs. No evidence of publication bias was observed.

Conclusion

Patients with advanced GIST harboring a KIT exon 11 mutation have the best response rate and long-term survival with imatinib treatment. Mutation analysis would be more helpful than KIT expression analysis to decide appropriate therapy for a specific patient.     

毛细管气相色谱法测定甲磺酸伊马替尼中残留有机溶剂

目的：建立可同时测定甲磺酸伊马替尼原料药中甲醇、乙醇和N''N - 二甲基甲酰胺（DMF）等3 种残留有机溶剂的毛细管气相色谱法。方法：采用WondaCAP WAX 毛细管柱为色谱柱,程序升温,N2 为载气,载气流速为4.0 mL ? min-1,氢火焰离子化检测器,检测器温度为250 ℃,进样口温度为200 ℃,进样量为1.0 μL。以正丁醇为内标,通过内标法计算样品中3 种有机溶剂残留量。结果：甲醇、乙醇和DMF 在所建立的色谱条件下均能完全分离,分别在2.94~44.11、4.91~73.68 和0.084~12.60 mg ? L-1 的质量浓度范围内线性关系良好（r =0.9940~0.9985）,进样精密度（RSD）均小于5.0%（n =6）,平均回收率为104.8%~105.8%（RSD<5.0%,n =9）,定量限分别为0.20、0.33 和0.08 ng（信噪比为10 ∶ 1）,检测限分别为0.05、0.11 和0.02 ng（信噪比为3 ∶ 1）。样品中未检出甲醇和DMF,乙醇含量低于有关限度规定。结论：该方法简便、准确、灵敏、重复性好,可用于甲磺酸伊马替尼原料药中残留有机溶剂的检测。     

Synergy between Proteasome Inhibitors and Imatinib Mesylate in Chronic Myeloid Leukemia

Background

Resistance developed by leukemic cells, unsatisfactory efficacy on patients with chronic myeloid leukemia (CML) at accelerated and blastic phases, and potential cardiotoxity, have been limitations for imatinib mesylate (IM) in treating CML. Whether low dose IM in combination with agents of distinct but related mechanisms could be one of the strategies to overcome these concerns warrants careful investigation.

Methods and Findings

We tested the therapeutic efficacies as well as adverse effects of low dose IM in combination with proteasome inhibitor, Bortezomib (BOR) or proteasome inhibitor I (PSI), in two CML murine models, and investigated possible mechanisms of action on CML cells. Our results demonstrated that low dose IM in combination with BOR exerted satisfactory efficacy in prolongation of life span and inhibition of tumor growth in mice, and did not cause cardiotoxicity or body weight loss. Consistently, BOR and PSI enhanced IM-induced inhibition of long-term clonogenic activity and short-term cell growth of CML stem/progenitor cells, and potentiated IM-caused inhibition of proliferation and induction of apoptosis of BCR-ABL+ cells. IM/BOR and IM/PSI inhibited Bcl-2, increased cytoplasmic cytochrome C, and activated caspases. While exerting suppressive effects on BCR-ABL, E2F1, and β-catenin, IM/BOR and IM/PSI inhibited proteasomal degradation of protein phosphatase 2A (PP2A), leading to a re-activation of this important negative regulator of BCR-ABL. In addition, both combination therapties inhibited Bruton''s tyrosine kinase via suppression of NFκB.

Conclusion

These data suggest that combined use of tyrosine kinase inhibitor and proteasome inhibitor might be helpful for optimizing CML treatment.     

Pharmacokinetic Resistance to Imatinib Mesylate: Role of the ABC Drug Pumps ABCG2 (BCRP) and ABCB1 (MDR1) in the Oral Bioavailability of Imatinib

Imatinib mesylate is a selective tyrosine kinase inhibitor that is successfully used in the treatment of chronic myeloid leukaemias and gastrointestinal stromal tumours. The drug is taken orally on a daily basis in order to suppress tumour growth. Unfortunately, the vast majority of patients will eventually progress while on therapy. It is generally thought that this acquired unresponsiveness is due to gene amplification or somatic mutations in the drug’s target genes. However, we have now evidence, based on several in vitro and in vivo observations suggesting that pharmacokinetic resistance may also play a definitive role in the ultimate resistance of patients on chronic imatinib. Our findings may have serious implications for the chronic imatinib treatment of cancer patients.     

Strongyloidiasis in a Diabetic Patient Accompanied by Gastrointestinal Stromal Tumor: Cause of Eosinophilia Unresponsive to Steroid Therapy

We report here a case of strongyloidiasis in a 72-year-old diabetic patient (woman) accompanied by gastrointestinal stromal tumor receiving imatinib therapy, first diagnosed as hypereosinophilic syndrome and treated with steroids for uncontrolled eosinophilia. She suffered from lower back pain and intermittent abdominal discomfort with nausea and diagnosed with gastrointestinal stromal tumor. After post-operative imatinib treatment eosinophilia persisted, so that steroid therapy was started under an impression of hypereosinophilic syndrome. In spite of 6 months steroid therapy, eosinophilia persisted. Stool examination was performed to rule out intestinal helminth infections. Rhabditoid larvae of Strongyloides stercoralis were detected and the patient was diagnosed as strongyloidiasis. This diagnosis was confirmed again by PCR. The patient was treated with albendazole for 14 days and her abdominal pain and diarrhea improved. This case highlights the need for thorough investigation, including molecular approaches, to test for strongyloidiasis before and during steroid therapies.     

Selecting Tyrosine Kinase Inhibitors for Gastrointestinal Stromal Tumor with Secondary KIT Activation-Loop Domain Mutations

Advanced gastrointestinal stromal tumors (GIST), a KIT oncogene-driven tumor, on imatinib mesylate (IM) treatment may develop secondary KIT mutations to confer IM-resistant phenotype. Second-line sunitinib malate (SU) therapy is largely ineffective for IM-resistant GISTs with secondary exon 17 (activation-loop domain) mutations. We established an in vitro cell-based platform consisting of a series of COS-1 cells expressing KIT cDNA constructs encoding common primary±secondary mutations observed in GISTs, to compare the activity of several commercially available tyrosine kinase inhibitors on inhibiting the phosphorylation of mutant KIT proteins at their clinically achievable plasma steady-state concentration (Css). The inhibitory efficacies on KIT exon 11/17 mutants were further validated by growth inhibition assay on GIST48 cells, and underlying molecular-structure mechanisms were investigated by molecular modeling. Our results showed that SU more effectively inhibited mutant KIT with secondary exon 13 or 14 mutations than those with secondary exon 17 mutations, as clinically indicated. On contrary, at individual Css, nilotinib and sorafenib more profoundly inhibited the phosphorylation of KIT with secondary exon 17 mutations and the growth of GIST48 cells than IM, SU, and dasatinib. Molecular modeling analysis showed fragment deletion of exon 11 and point mutation on exon 17 would lead to a shift of KIT conformational equilibrium toward active form, for which nilotinib and sorafenib bound more stably than IM and SU. In current preclinical study, nilotinib and sorafenib are more active in IM-resistant GISTs with secondary exon 17 mutation than SU that deserve further clinical investigation.     

ERK2, but Not ERK1, Mediates Acquired and “De novo” Resistance to Imatinib Mesylate: Implication for CML Therapy

Resistance to Imatinib Mesylate (IM) is a major problem in Chronic Myelogenous Leukaemia management. Most of the studies about resistance have focused on point mutations on BCR/ABL. However, other types of resistance that do not imply mutations in BCR/ABL have been also described. In the present report we aim to study the role of several MAPK in IM resistance not associate to BCR/ABL mutations. Therefore we used an experimental system of resistant cell lines generated by co-culturing with IM (K562, Lama 84) as well as primary material from resistant and responder patient without BCR/ABL mutations. Here we demonstrate that Erk5 and p38MAPK signaling pathways are not implicated in the acquired resistance phenotype. However, Erk2, but not Erk1, is critical for the acquired resistance to IM. In fact, Bcr/Abl activates preferentially Erk2 in transient transfection in a dose dependent fashion through the c-Abl part of the chimeric protein. Finally, we present evidences demonstrating how constitutive activation of Erk2 is a de novo mechanism of resistance to IM. In summary our data support the use of therapeutic approaches based on Erk2 inhibition, which could be added to the therapeutic armamentarium to fight CML, especially when IM resistance develops secondary to Erk2 activation.     

Fractioned Dose Regimen of Sunitinib for Patients with Gastrointestinal Stromal Tumor: A Pharmacokinetic and Treatment Efficacy Study

AIM: Sunitinib has shown benefit in patients with imatinib (IM)–resistant gastrointestinal stromal tumor (GIST). However, its advantages are somewhat diminished because of associated toxicities. Herein, we clarify the efficacy and safety of fractioned dose regimen of sunitinib by a pharmacokinetic and efficacy study. MATERIALS AND METHODS: Between 2001 and March 2013, a total of 214 patients with metastatic GIST was treated at Chang Gung Memorial Hospital. Among them, 55 (11.6%) patients who received sunitinib were investigated. One group of patients was administered with standard dose of once-daily sunitinib (standard dose group) and the other group was administered with standard total daily dose of sunitinib in fractioned doses (fractioned dose group). RESULTS: Thirty-two male and 23 female patients with a median age of 55 years received sunitinib. The median duration of sunitinib administration was 9.2 months. The clinical benefit was 65.2%. The mean peak blood level of sunitinib in patients with fractioned doses was significantly lower than that in those with once-daily dose (83.4 vs 50.1 ng/ml, P = .01). The rates of adverse effects of hand-foot syndrome, mucositis, and yellow skin were significantly decreased by fractioned doses of sunitinib. However, the progression-free and overall survival did not differ between patients with different treatment regimens. CONCLUSION: The fractioned dose regimen of sunitinib appears to be a safe and effective treatment for patients with IM-resistant/intolerant GISTs. Significantly decreased toxicity of this regimen could be explained by significantly lower peak sunitinib blood level. However, the treatment efficacy is not reduced by this regimen.     

Formulation and In Vitro,In Vivo Evaluation of Effervescent Floating Sustained-Release Imatinib Mesylate Tablet

Introduction

Imatinib mesylate is an antineoplastic agent which has high absorption in the upper part of the gastrointestinal tract (GIT). Conventional imatinib mesylate (Gleevec) tablets produce rapid and relatively high peak blood levels and requires frequent administration to keep the plasma drug level at an effective range. This might cause side effects, reduced effectiveness and poor therapeutic management. Therefore, floating sustained-release Imatinib tablets were developed to allow the tablets to be released in the upper part of the GIT and overcome the inadequacy of conventional tablets.

Methodology

Floating sustained-release Imatinib mesylate tablets were prepared using the wet granulation method. Tablets were formulated using Hydroxypropyl Methylcellulose (HPMC K4M), with Sodium alginate (SA) and Carbomer 934P (CP) as release-retarding polymers, sodium bicarbonate (NaHCO₃) as the effervescent agent and lactose as a filler. Floating behavior, in vitro drug release, and swelling index studies were conducted. Initial and total drug release duration was compared with a commercial tablet (Gleevec) in 0.1 N HCl (pH 1.2) at 37 ± 0.5°C for 24 hours. Tablets were then evaluated for various physical parameters, including weight variation, thickness, hardness, friability, and drug content. Consequently, 6 months of physical stability studies and in vitro gastro-retentive studies were conducted.

Results and Discussion

Statistical data analysis revealed that tablets containing a composition of 14.67% w/w HPMC K4M, 10.67%, w/w Na alginate, 1.33%, w/w Carbomer 934P and 9.33%, w/w NaHCO₃ produced the most favorable formulation to develop 24-hour sustained-release tablets with optimum floating behavior and satisfactory physicochemical characteristics. Furthermore, in vitro release study revealed that the formulated SR tablet had significantly lower C_max and higher T_max compared to the conventional tablet (Gleevec). Thus, formulated SR tablets preserved persistent concentration of plasma up to 24 hours.

Conclusion

In conclusion, in order to suggest a better drug delivery system with constant favorable release, resulting in optimized absorption and less side effects, formulated CP-HPMC-SA based imatinib mesylate floating sustained-release tablets can be a promising candidate for cancer chemotherapy.     

c-KIT positive Gastrointestinal Stromal Tumor presenting with acute bleeding in a patient with neurofibromatosis type 1: a case report

Background

Gastrointestinal stromal tumours are rare (GIST). However, the incidence of GIST among neurofibromatosis type 1 (NF-1) patients is approximately 3.9-25%. GIST can present clinically in different ways such as abdominal pain, gastrointestinal bleeding and obstruction.

Case report

We present 51 year female patient admitted with Background of neurofibromatosis type 1 admitted with melena. OGD has been done and showed duodenitis with large volume fresh blood in distal duodenum but no obvious bleeding point. Exploratory laparotomy revealed smooth nodular masses on the serosal surface of jejunum. Small bowel resection and side-to-side anastomosis were performed. Histopathoogical examination revealed small bowel gasrointestinal stromal tumour with low risk malignant potential.

Conclusion

The incidence of GIST among neurofibromatosis type 1 (NF-1) patients is not uncommon and we should pay attention to gastrointestinal manifestation in such patients.