Predictive factors for long-term effects of imatinib therapy in patients with inoperable/metastatic CD117(+) gastrointestinal stromal tumors (GISTs)

Survival of advanced/recurrent gastrointestinal stromal tumors treated with tyrosine kinase inhibitors in Taiwan: a nationwide registry study

BACKGROUND

Most gastrointestinal stromal tumors (GISTs) harbor c-KIT or PDGFRA mutations. Administration of tyrosine kinase inhibitors (TKIs) has significantly improved the survival of patients with GISTs. We aimed to evaluate the clinical outcome of advanced or recurrent GIST patients in Taiwan.

METHODS

Patients diagnosed between 2010 and 2020 were enrolled. The collected data included baseline characteristics, treatment pattern, treatment outcome, genetic aberrations and survival status. Progression-free survival (PFS) and overall survival (OS) were analyzed and plotted with the Kaplan-Meier method. Cox regression analysis was used to analyze the prognostic factors of survival.

RESULTS

A total of 224 patients with advanced or recurrent GISTs treated with TKIs were enrolled. All patients received imatinib treatment. Ninety-three and 42 patients received sunitinib and regorafenib treatment, respectively. The 48-month PFS and OS rates for patients treated with imatinib were 50.5% and 79.5%, respectively. c-KIT exon 9 and PDGFRA mutations were prognostic factors for a poor PFS and PDGFRA mutation was a prognostic factor for a poor OS in patients treated with imatinib in multivariate Cox regression analysis. The median PFS of patients who received sunitinib treatment was 12.76 months (95% confidence interval (CI), 11.01-14.52). Patients with c-KIT exon 9 mutations had a longer PFS than those with other genetic aberrations. The median PFS of patients treated with regorafenib was 7.14 months (95% CI, 3.39-10.89).

CONCLUSIONS

We present real-world clinical outcomes for advanced GIST patients treated with TKIs and identify mutational status as an independent prognostic factor for patient survival.

TKI Treatment Sequencing in Advanced Gastrointestinal Stromal Tumors

Prior to the early 2000s, patients with advanced gastrointestinal stromal tumors (GIST) had very poor prognoses owing to a lack of effective therapies. The development of tyrosine kinase inhibitors at the turn of the century significantly improved the overall survival for patients with GIST. The resounding success of imatinib in the first clinical trial of a tyrosine kinase inhibitor to treat GIST led to its approval for first-line therapy for advanced GIST; this study was open to all comers and not restricted to any GIST subtype(s). The trials that led to the approvals of second-, third-, and fourth-line therapy for advanced GIST were also open to all patients with advanced/metastatic GIST. Only in retrospect do we realize the role that the molecular subtypes played in the results observed in these studies. In this review, we discuss the studies that led to the US Food and Drug Administration approval of imatinib (first line), sunitinib (second line), regorafenib (third line), and ripretinib (fourth line) for advanced KIT-mutant GIST. In addition, we review how information about GIST molecular subtypes has been used to accelerate the approval of other targeted therapies for non-KIT mutant GIST, leading to the approval of five additional drugs indicated for the treatment of specific GIST molecular subtypes. We also discuss how our understanding of the molecular subtypes will play a role in the next generation of therapeutic approaches for treating advanced GIST.

New response evaluation criteria using early morphological change in imatinib treatment for patients with gastrointestinal stromal tumor

BACKGROUND

The introduction of molecularly targeted drugs, including imatinib, has greatly improved the prognosis of gastrointestinal stromal tumor (GIST), and based on the different response image, the methods of response evaluation have been established for GISTs. Furthrmore, the best response evaluation using them has been reported to be associated with progression-free survival (PFS) in imatinib treatment. However, since it is more important to predict the clinical outcomes of imatinib treatment in "early treatment phase", new predicting factor in earlier stage is desired to work out the whole strategy of each patient. Early morphological change (EMC) was previously reported as a predictive marker for molecularly targeted drugs in metastatic colorectal cancer. The purpose of the present study was to verify the efficacy of EMC in predicting the outcome in patients with GIST receiving imatinib at early evaluation.

METHODS

We retrospectively reviewed 66 patients. EMC in computed tomography (CT) image was evaluated, and the patients were categorized into two groups: active MR (morphological response) (+) group and active MR (-) group. We investigated the association between the presence of active MR and clinical outcomes.

RESULTS

Forty-five patients had active MR ( +). The median progression-free survival (PFS) in patients with/without active MR was 49/23 months (P = 0.0039).

CONCLUSION

The evaluation criteria based on EMC could be a sensitive method to predict the clinical outcome of imatinib treatment for patients with unresectable GIST.

Prognostic Role of Plasma PD-1, PD-L1, pan-BTN3As and BTN3A1 in Patients Affected by Metastatic Gastrointestinal Stromal Tumors: Can Immune Checkpoints Act as a Sentinel for Short-Term Survival?

Gastrointestinal stromal tumors (GISTs) represent 1% of all primary gastrointestinal tumors. Immune surveillance is often overcome by cancer cells due to the activation of immunoregulatory molecules such as programmed death protein (PD-1) and its ligand PD-L1, and butyrophilin sub-family 3A/CD277 receptors (BTN3A). Because several studies demonstrated that tumor PD-1 and PD-L1 expression may have a prominent prognostic function, this investigation aimed to discover if soluble forms of these molecules may be useful in predicting survival of metastatic GIST (mGIST) patients. Through specific ad hoc developed ELISA assays not yet available on the market, the circulating PD-1, PD-L1, BTN3A1, and pan-BTN3As levels were examined in 30 c-KIT exon 11-mutated mGIST patients, prior to imatinib therapy. Using specific thresholds derived by ROC analysis, we found that high baseline levels of sPD-1 (>8.1 ng/mL), sPD-L1 (>0.7 ng/mL), sBTN3A1 (>7.0 ng/mL), and pan-BTN3As (>5.0 ng/mL) were correlated with shorter progression-free survival (PFS) and poor prognosis. Contrariwise, subjects with lower plasma concentrations exhibited a median PFS about 20 months longer than to the earlier. Finally, an additional multivariate analysis revealed that circulating levels of sPD-L1 ≤ 0.7 ng/mL and pan-sBTN3As ≤ 5.0 ng/mL, and the absence of KIT exon 11 deletions or delins at codons 557 and/or 558 were associated with a longer PFS in mGIST patients. Our investigation, for the first time, revealed that evaluating the plasma concentration of some immune checkpoints may help prognosticate survival in mGIST patients, suggesting their potential use as prognostic biomarkers beyond the presence of KIT exon 11 Del or Delins at codons 557/558.

Blood neutrophil-to-lymphocyte ratio is associated with prognosis in advanced gastrointestinal stromal tumors treated with imatinib

INTRODUCTION

Neutrophil-to-lymphocyte ratio (NLR) was shown to be prognostic in several solid malignancies. There are limited data about predictive/prognostic value of NLR during targeted therapy of patients with advanced gastrointestinal stromal tumors (GIST). The aim of this study was to asses a clinical value of this ratio in patients with advanced GIST.

METHODS

Between 2001 and 2016, 385 patients with metastatic/unresectable GIST treated initially with imatinib were included in the analysis. In all patients, the NLR was assessed at the baseline, after 3 months of treatment, and upon disease progression (or last observation). The cutoff values for NLR were set at 2.7 and 5.4. Kaplan-Meier survival probability estimation with log-rank test and Cox proportional hazards model were used for analysis.

RESULTS

Median progression-free survival (PFS) on imatinib treatment was 44.8 months, 5-year rate 43%; median overall survival (OS) 87.2 months, 10-year rate 36.3%. NLR >2.7 at baseline was significantly associated with poorer OS and PFS: median OS was 89.3 months (95% confidence interval [CI] 80.2-115) for NLR ratio ≤2.7 vs 59.4 months (95% CI 48.6-82) for NLR >2.7 (p < .001); median PFS was 59.4 vs 32.7 (p < .001), respectively. In multivariate model adjusted for mitotic index and driver mutation in the tumor (KIT exon 11 mutation versus other), NLR ratio was proven to be statistically significant (hazard ratio 1.09; 95% CI 1.01-1.19; p = .030). Among patients with disease progression, NLR >2.7 assessed at the third month of treatment was linked with significantly shorter median time to progression (7.5 vs 19 months).

CONCLUSIONS

Our results demonstrate the usefulness of NLR as a prognostic and predictive marker as well as a marker for treatment monitoring in patients with advanced GIST treated with imatinib.

Gastrointestinal Stromal Tumors (GISTs): From Science to Targeted Therapy

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. GISTs represent a distinct category of tumors characterized by oncogenic mutations of the KIT receptor tyrosine kinase in a majority of patients. KIT is useful not only for the diagnosis but also for targeted therapy of this disease. Imatinib, a tyrosine kinase inhibitor, is widely used in advanced and metastatic GISTs. This agent revolutionized the treatment strategy of advanced disease and is being tested in the neoadjuvant and adjuvant settings with encouraging results. New therapeutic agents like sunitinib have now been approved, enriching the treatment scenario for imatinib-resistant GISTs. The present review reports on the peculiar characteristics of this disease through its biology and molecular patterns, focusing on the predictive value of KIT mutations and their correlation with clinical outcome as well as on the activity of and resistance to approved targeted drugs.

Combined Therapy of Gastrointestinal Stromal Tumors

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

Successful treatment with personalized dosage of imatinib in elderly patients with gastrointestinal stromal tumors

Imatinib is the standard first-line therapy for metastatic gastrointestinal stromal tumors. It has markedly improved the prognosis and outcome of patients affected by gastrointestinal stromal tumors, especially in the case of exon 11 KIT mutations. Imatinib-associated adverse events are generally mild to moderate; however, in clinical practice, intolerance caused by chronic toxicities frequently leads to breaks in treatment. This is particularly true in elderly patients in whom age, decline in drug metabolism, and polypharmacy, with a possible drug-drug interaction, may influence the tolerability of imatinib. In the present article, we report our extensive experience with the management of imatinib therapy in a 'real' population, in particular in very elderly patients, discussing whether the use of personalized imatinib dosage could be a safe and advantageous option, enabling continuous administration, thus ensuring effective treatment. Only a few case reports in the literature provide data on outcome with low tailored dosage of imatinib and none of them has been carried out on a Western population. Here, we report four cases treated with low imatinib dosage as a safe and useful option enabling continued treatment with imatinib, improving tolerance, and maintaining good and lasting disease control.

Initial Hyperleukocytosis and Neutrophilia in Nasopharyngeal Carcinoma: Incidence and Prognostic Impact

Background

This study aimed to evaluate initial hyperleukocytosis and neutrophilia as prognostic indicators in patients with nasopharyngeal carcinoma.

Methods

A retrospective analysis of 5,854 patients identified from a cohort of 6,035 patients diagnosed with nasopharyngeal carcinoma was performed with initial hyperleukocytosis and neutrophilia analyzed as prognostic factors. Multivariate Cox proportional hazards analyses were applied.

Results

Hyperleukocytosis was observed in 508 patients (8.7%). Multivariate analysis showed that initial hyperleukocytosis was an independent predictor of death (HR 1.40, 95%CI 1.15–1.70, p = 0.001), progression (HR 1.25, 95%CI 1.06–1.47, p = 0.007) and, marginally, distant metastasis (HR 1.21, 95%CI 0.97–1.52, p = 0.088). Neutrophilia was also an independent predictor of death (HR 1.46, 95%CI 1.18–1.81, p = 0.001), progression (HR 1.31, 95%CI 1.10–1.56, p = 0.003), and distant metastasis (HR 1.29, 95%CI 1.02–1.65, p = 0.036), after adjusting for prognostic factors and excluding hyperleukocytosis.

Conclusion

Initial hyperleukocytosis and neutrophilia were independent, poor prognostic factors and may be convenient and useful biological markers for survival of patients with nasopharyngeal carcinoma.

What are the current outcomes of advanced gastrointestinal stromal tumors: who are the long-term survivors treated initially with imatinib?

The introduction of imatinib to clinical practice revolutionized therapy of advanced gastrointestinal stromal tumors (GIST), but its long-term results have been only just collected. We have attempted to identify factors related to the long-term survival. We have analyzed the data of 430 inoperable/metastatic/recurrent GIST patients treated with imatinib in reference centers, assessed the factors influencing the long-term overall survival (OS), and compared the outcomes in three periods of initiation of imatinib therapy during one decade (2001–2003, 2004–2006, 2007–2010). During analyzed time periods, we have found decrease in median largest tumor size at the start of imatinib therapy: 90.5 mm (2001–2003) versus 74 mm (2004–2006) versus 58 mm (2007–2010) (p = 0.002). Median progression-free survival (PFS) on 1st line imatinib was 37.5 months, without differences in PFS between three groups. Median OS was 5.8 years, 8-year OS rate was 43 %, and no difference in OS was demonstrated for patients treated in analyzed time periods. Independent good prognostic factors for longer OS were as follows: surgery of residual disease, initial WHO performance status 0/1, normal baseline albumin level, and the presence of exon 11 KIT mutations. Current median OS in advanced GIST reaches 6 years. The long-term survivors were characterized by smaller maximal tumors at imatinib start, better blood tests results, better performance status, and the surgical removal of residual disease. The latter might reduce the impact of tumor size and equalize the long-term results of therapy during last decade from introduction of imatinib. After introduction of subsequent lines of therapy (as sunitinib), the effect of primary mutational status on the long-term OS is also less visible.

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.

Upregulated ZO-1 correlates with favorable survival of gastrointestinal stromal tumor

Zonula occludens-1 (ZO-1) is a membrane-scaffolding protein that plays an important role in maintaining tight-junction integrity, which is disrupted in many invasive cancers and intestinal diseases. However, the expression of ZO-1 in gastrointestinal stromal tumor (GIST) and its relationship with clinical characteristics of this disease remain poorly understood. In this study, immunohistochemical analysis using tissue microarray was employed to evaluate the expression of ZO-1 in GIST and to investigate the relationship between its expression and GIST prognosis. High ZO-1 expression was displayed in 71.8 % of GIST patients, which was related to tumor diameter (p < 0.05). The Kaplan-Meier method and log-rank test indicated that high ZO-1 expression, small tumor diameter, tumor position in the esophagus, and a borderline-to-intermediate tumor grade displayed significant correlations with longer survival of GIST patients. The data suggest that ZO-1 expression is correlated with malignant phenotypes of GIST and it may serve as a favorable prognostic factor for GIST. These results also support a role for ZO-1 as a tumor-suppressor gene in GIST.

Immunomonitoring and prognostic relevance of neutrophils in clinical trials

The clinical relevance of the interaction between human cancer and neutrophils has recently begun to emerge. This review will focus on recently published articles regarding immunomonitoring of neutrophils in blood and tumor tissue in clinical trials comprising the main human tumor types, with a strong emphasis on independent prognostic relevance assessed by multivariate analyses. The prognostic role of tumor-infiltrating neutrophils, elevated blood neutrophils and elevated blood neutrophil/lymphocyte ratio has been associated with poor clinical outcome in several human cancers, most notably in renal cell carcinoma, melanoma, colorectal cancer, hepatocellular carcinoma, cholangiocarcinoma, glioblastoma, GIST, gastric, esophageal, lung, ovarian and head and neck cancer. A striking finding is the notion that high baseline neutrophil count in either tumor or blood, or both, was identified as strong, independent risk factor for poor outcome in multivariate analyses, and the negative prognostic impact of neutrophils was not eliminated by increasing the dose of cytokines, chemotherapy, or targeted therapy. For several cancers, patients benefit most from therapy if baseline neutrophil was low. Thus, baseline neutrophils over-ride nadir counts in prognostic significance. In summary, a proportion of patients who do not experience benefit from surgery or medical intervention may be associated with a worst prognosis because they are characterized by baseline tumor-related neutrophilia protecting them from benefit from therapy. Further research to unraveling the cancer biology and new treatment options is encouraged.

Clinical outcomes of gastrointestinal stromal tumor in southern Thailand

AIM: To review a single institutional experience in clinical management of gastrointestinal stromal tumors (GIST) and analyze for factors determining treatment outcome.

METHODS: Clinicopathological data of patients with a diagnosis of GIST who were treated at our institute during November 2004 to September 2009 were retrospectively reviewed.

RESULTS: Ninety-nine cases were included in the analysis. Primary tumor sites were at the stomach in and small bowel in 44% and 33%, respectively. Thirty-one cases already had metastasis at presentation and the most common metastatic site was the liver. Sixty-four cases (65%) were in the high-risk category. Surgical treatment was performed in 77 cases (78%), 3 of whom received upfront targeted therapy. Complete resection was achieved in 56 cases (73% of operative cases) and of whom 27 developed local recurrence or distant metastasis at a median duration of 2 years. Imatinib was given as a primary therapy in unresectable cases (25 cases) and as an adjuvant in cases with residual tumor (21 cases). Targeted therapy gave partial response in 7 cases (15%), stable disease in 27 cases (57%) and progressive disease in 13 cases (28%). Four-year overall survival was 74% (95% CI: 61%-83%). Univariate survival analysis found that low-risk tumor, gastric site, complete resection and response to imatinib were associated with better survival.

CONCLUSION: The overall outcomes of GIST can be predicted by risk-categorization. Surgery alone may not be a curative treatment for GIST. Response to targeted therapy is a crucial survival determinant in these patients.

Blood neutrophil-to-lymphocyte ratio is prognostic in gastrointestinal stromal tumor

BACKGROUND

The immune system has been shown to play an important role in gastrointestinal stromal tumor (GIST). The neutrophil-to-lymphocyte ratio (NLR) in blood is an easily assessable parameter of systemic inflammatory response. The aim of this study was to determine whether the NLR is prognostic in GIST.

METHODS

A total of 339 previously untreated patients with primary, localized GIST operated at our institution between 1995 and 2010 were identified from a prospectively collected sarcoma database. NLR was assessed preoperatively. Patients who received adjuvant imatinib treatment were excluded from the analysis (n = 64). Cox regression models were calculated and correlation analyses were performed.

RESULTS

On univariate analysis, NLR was associated with recurrence-free survival (RFS) (P = 0.003, hazard ratio 3.3, 95 % confidence interval 1.5-7.4). Patients with a low NLR had a 1- and 5-year RFS of 98 and 91 %, compared with 89 and 76 % in those with a high NLR. The median RFS was not reached. Positive correlations were found between NLR and mitotic rate (Pearson correlation coefficient [r] = 0.15, P = 0.03), and NLR and tumor size (r = 0.36, P = 0.0001). RFS in patients with a GIST >5 cm with low NLR was significantly longer compared to patients with high NLR (P = 0.002). Flow cytometry analysis of freshly obtained GISTs revealed that neutrophils constituted a minimal percentage of intratumoral immune cells.

CONCLUSIONS

NLR is a surrogate for high-risk tumor features. Elevated blood NLR appears to represent systemic inflammation in patients with high-risk GIST.

Current management and prognostic features for gastrointestinal stromal tumor (GIST)

Stromal or mesenchymal neoplasms affecting the gastrointestinal (GI) tract have undergone a remarkable evolution in how they are perceived, classified, approached, diagnosed and managed over the last 30 years. Gastrointestinal stromal tumors (GIST) account for approximately 1% to 3% of all malignant GI tumors. The clinical features can vary depending on the anatomic location, size and aggressiveness of the tumor. Metastatic GIST represents a successful example of molecular targeted therapy. In this comprehensive review, we discuss the epidemiology, clinical features and diagnostic modalities for GIST. We also describe treatment options for early stage, locally advanced and metastatic GIST. Indications for neoadjuvant and adjuvant therapy along with duration of therapy are also explained. A brief discussion of latest biomarkers and updates from recent meetings is also provided.

Recent advances and novel agents for gastrointestinal stromal tumor (GIST)

The discovery of CD117 mutation in almost all gastrointestinal stromal tumors (GISTs) marked a milestone. Other spindle cell neoplasms arising from the GI tract including lipoma, schwannoma, hemangioma, leiomyoma, and leiomyosarcoma are typically CD117-negative. GIST research and clinical care now represent a paradigm of translating discoveries in the molecular pathogenesis of cancer into highly effective targeted therapies that selectively inhibit etiologic “driver” pathways, leading to dramatically improved clinical outcomes. A series of investigations and trials are underway to develop novel and effective ways to treat patients with GIST. In this review, we discuss the highlights of recent advances and novel agents for GIST therapy.

The outcome and predictive factors of sunitinib therapy in advanced gastrointestinal stromal tumors (GIST) after imatinib failure - one institution study

BACKGROUND

Gastrointestinal stromal tumors (GIST) mutational status is recognized factor related to the results of tyrosine kinase inhibitors therapy such as imatinib (IM) or sunitinib (SU). Arterial hypertension (AH) is common adverse event related to SU, reported as predictive factor in renal cell carcinoma. The aim of the study was to analyze the outcomes and factors predicting results of SU therapy in inoperable/metastatic CD117(+) GIST patients after IM failure.

METHODS

We identified 137 consecutive patients with advanced inoperable/metastatic GIST treated in one center with SU (2nd line treatment). Median follow-up time was 23 months. Additionally, in 39 patients there were analyzed selected constitutive single nucleotide polymorphisms (SNPs) of VEGFA and VEGFR2 genes.

RESULTS

One year progression-free survival (PFS; calculated from the start of SU) rate was 42% and median PFS was 43 weeks. The estimated overall survival (OS, calculated both from start of SU or IM) was 74 weeks and 51 months, respectively. One-year PFS was 65% (median 74 weeks) in 55 patients with AH vs. 22% (median 17 weeks) in patients without AH. Patients with primary tumors carrying mutations in KIT exon 9 or wild-type had substantially better 1-year PFS (68% and 57%; median 65.5 and 50.5 weeks, respectively) than patients having tumors with KIT exon 11 or PDGFRA mutations (34% and 15%; median 36.8 and 9 weeks, respectively). We identified two independent factors with significant impact on PFS and OS in univariate and multivariate analysis: primary tumor genotype and presence of AH. The most common adverse events during therapy were: fatigue, AH, hypothyroidism, hand and foot syndrome, mucositis, skin reactions, dyspepsia, and diarrhea. Two deaths were assessed as related to tumor rupture caused by reaction to SU therapy. The presence of C-allele in rs833061 and the T-allele in rs3025039 polymorphism of VEGFA were associated with significantly higher risk of hypothyroidism (OR: 10.0 p = 0.041 and OR: 10.5; p = 0.015, respectively).

CONCLUSIONS

We confirmed that many advanced GIST patients benefit from SU therapy with OS > 1.5 year. Primary tumor KIT/PDGFRA genotype and SU-induced AH, as surrogate of its antiangiogenic activity are two independent factors influencing both PFS and OS.

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.

Efficacy evaluation of imatinib treatment in patients with gastrointestinal stromal tumors: A meta-analysis

AIM: To perform a meta-analysis to derive a more precise estimation of imatinib treatment for different genotypes of gastrointestinal stromal tumors (GIST).

METHODS: Studies were identified by searching PubMed and Embase. Inclusive criteria were patients with exon 9-mutant, exon 11-mutant or wide type (WT) GIST, receiving chemotherapy of imatinib for clinical trial, and efficacy evaluation was cumulative response (CR) including complete response and partial response. The odds ratios (OR) for CR in stem cell factor receptor (KIT) mutation patients vs WT genotype patients, KIT exon 11-mutant genotype patients vs KIT exon 9-mutant genotype patients and KIT exon 9-mutant genotype patients vs WT genotype patients were calculated with 95% confidence interval (CI) for each study as an estimation of the efficacy of imatinib.

RESULTS: Five studies including 927 patients were involved in this meta-analysis. The overall OR (KIT group vs WT group) was 3.34 (95% CI: 2.30-4.86, P < 0.00001, P_{heterogeneity} = 0.04). The overall OR in KIT exon 11 group vs KIT exon 9 group was 3.29 (95% CI: 2.17-5.00, P < 0.00001, P_{heterogeneity} = 0.33). The overall OR in KIT exon 9 group vs WT group was 1.23 (95% CI: 0.73-2.10, P = 0.44, P_{heterogeneity} = 0.42).

CONCLUSION: Most patients with different genotypes of GIST and KIT exon 11-mutant will benefit from the individualized treatment of imatinib.

Gastrointestinal stromal tumors: key to diagnosis and choice of therapy

The common feature of gastrointestinal stromal tumors (GISTs) is the expression of KIT protein or acquisition of activating, constitutive mutations in the KIT or platelet-derived growth factor receptor alpha (PDGFRA) genes that are the early oncogenic events during GIST development. With these discoveries, GIST has emerged as a distinct sarcoma entity, enabling the introduction of targeted therapy using the inhibition of KIT/PDGFRA and their downstream signaling cascade. The introduction of a small-molecule tyrosine kinase inhibitor, imatinib mesylate, to clinical practice has revolutionized the treatment of patients with advanced GISTs and is currently approved as first-line treatment for patients with metastatic and/or inoperable GISTs. Mutation screening is currently a tool in GIST diagnosis, assessment of sensitivity to tyrosine kinase inhibitors, and prediction of achieving response to molecularly targeted therapy. This article discusses the histologic and molecular criteria for distinguishing GISTs from other types of sarcoma, and the molecular diagnostic tools that are currently available or in development to assist in therapy decisions.