Gastrointestinal stromal tumors: key to diagnosis and choice of therapy

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.

Neoadjuvant imatinib: longer the better, need to modify risk stratification for adjuvant imatinib

BACKGROUND

Multimodality treatment of gastrointestinal stromal tumor (GIST) with surgery and adjuvant imatinib mesylate (IM), along with an emerging role for neoadjuvant IM prior to evaluation for resectability has resulted in high survival rates.

METHODS

We conducted a retrospective analysis of prospectively collected data of patients who underwent surgery for GIST, prior to or followed by IM therapy. A total of 112 patients underwent surgery between January 2009 and March 2015 at our centre. This included 27 patients with upfront resectable disease, 76 patients with locally advanced GIST who received neoadjuvant IM followed by surgery and 9 patients with metastatic disease who had excellent response to IM and were taken for surgery.

RESULTS

The primary tumor in the non metastatic patients was in the stomach (53%), duodenum (16%), rectum (12%), jejunum (11%), ileum (7%), and others (2%). Median duration of neoadjuvant IM was 5 months with 4 patients showing disease progression during neoadjuvant IM. Ninety-three percent of all patients had R0 resections, while 7% had R+ resections. The estimated 3- and 5-year DFS in non-metastatic patients was 86.1% and 67% respectively with a 3- and 5-year median OS of 95.4% and 91.7% respectively. Five-year PFS and OS for the metastatic patients was 88.8% and 100% respectively. Lack of adjuvant IM was the only factor related to inferior PFS and OS.

CONCLUSIONS

Longer duration of neoadjuvant IM should be considered in locally advanced GIST prior to surgery and resection may be considered in responding metastatic patients.

Role of surgery in patients with focally progressive gastrointestinal stromal tumors resistant to imatinib

The benefits of surgery for focally progressive gastrointestinal stromal tumor (GIST) during imatinib therapy are still in discussion. The aim of this study was to compare the outcomes of surgical resection of progressive lesions following tyrosine kinase inhibitor (TKI) therapy (S group) or TKI therapy alone (NS group) in GIST patients. We retrospectively investigated 57 patients with focally progressive GIST during imatinib therapy who were treated in Zhongshan hospital, Fudan University. Progression-free survival (PFS) and overall survival (OS) in the S group were significantly longer than those in the NS group. Among S group, the patients with R0 resection showed longer PFS than R2 resection; however, no difference was found between these two groups. Moreover, PFS and OS were not different in the NS-S group compared with S group. On multivariate analysis, surgery is an independent prognostic factor for longer PFS and OS. Our study supports the decision of treating GIST patients who were focally resistant to imatinib with surgery resection based on its benefit.

Clinical characteristics and prognostic indicators for metastatic melanoma: data from 446 patients in north China

Melanoma is an extremely rare tumor in Asia. This retrospective study aimed to identify the clinical characteristics and prognostic factors of metastatic melanoma patients at Tianjin Medical University Cancer Hospital over the last 30 years. Survival analysis was performed with Kaplan-Meier, log-rank test, and multivariate Cox regression method using SPSS 19.0 software. The 1-, 2-, and 5-year survival rates of metastatic melanoma patients were 52, 32, and 16 %, respectively. Median overall survival (OS) was 13.5 months, median progression-free survival (PFS) 9.0 months, and median disease-free survival 20.3 months. Furthermore, patients with a single metastatic site achieved better OS and PFS than those with two or more metastatic lesions (OS 21.6 vs. 8.9 months, P < 0.001; PFS 11.3 vs. 7.1 months, P < 0.001). Survival times of patients with visceral metastases were the shortest (OS 8.5 months; PFS 7.5 months). Specifically, patients with primary mucosal lesions had a worse OS (9.7 months) and PFS (6.8 months) than those with acral (19.2 and 15.6 months, respectively) or non-acral primary lesions (11.8 and 11.1 months, respectively). The treatment of advanced melanoma was unitary, and prognoses of patients with metastatic melanoma in China were poor. Visceral metastasis, multiple metastatic sites, and primary mucosal lesions were significant predictors of survival of patients with metastatic melanoma. Those with primary mucosal lesions had significantly worse survivals than those with primary cutaneous lesions. More active involvement in clinical studies and more feedback on various treatment options are required.

The safety of regorafenib for the treatment of gastrointestinal stromal tumors

INTRODUCTION

The management of gastrointestinal stromal tumors (GIST) evolved due to effective molecularly targeted therapy with imatinib and sunitinib which are used first- and second-line, respectively. However, due to the development of resistance to those drugs in the majority of patients, the need for third-line therapy arose.

AREAS COVERED

Regorafenib, an oral multitargeted inhibitor with activity against multiple kinases including KIT, RET, RAF1, BRAF, angiogenesis (VEGFR, TIE-2) and those involved in tumor microenvironment (PDGFR and FGFR) was introduced after the successful Phase III GRID (GIST - Regorafenib In progressive Disease) clinical trial. This study showed significant improvement in progression-free survival for patients receiving regorafenib compared to placebo (4.8 months vs 0.9 months). The treatment was reasonably well tolerated, with arterial hypertension, hand-foot syndrome, diarrhea being the most common grade ≥3 adverse events, which could be managed by dose reduction and supportive treatment. The aim of this paper is to describe, assess and advise on the safety of regorafenib as third-line therapy in GIST.

EXPERT OPINION

Regorafenib has demonstrated clinical benefit in GIST patients after progression on prior treatment with at least imatinib/sunitinib and currently it is the approved standard third-line option in therapy of advanced GIST. The safety profile is similar to other multikinase inhibitors with anti-VEGFR activity and is manageable.

Genomic mapping of pathways in endometrial adenocarcinoma and a gastrointestinal stromal tumor located in Meckel's diverticulum

The present study reports the case of a 71-year-old female patient diagnosed with endometrial adenocarcinoma, which was confirmed by histopathology. In the course of performing an elective hysterectomy with adnexa removal, a solid tumor located in Meckel's diverticulum (MD) was identified and excised. Due to the unique nature of the lesion, the tumor tissue underwent broad mapping of any genomic alterations once the histopathological examination was completed. The genetic testing was conducted using a high-resolution microarray and resulted in the identification of 45 genomic abnormalities, including 4 chromosomal aneuploidies. Within those regions, alterations of 87 known cancer genes were assigned. The involvement of v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog gene alteration was noted to be a key player for triggering gastrointestinal stromal tumor transformation for this unusual case. A total of 12 genes, showing mutual interaction in different cancer types or involved in diverse cellular processes, were identified. These reported data may shed light on the carcinogenesis of a rare MD tumor.

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.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Extended adjuvant therapy with imatinib in patients with gastrointestinal stromal tumors : recommendations for patient selection, risk assessment, and molecular response monitoring

On the basis of the recently published results of a clinical trial comparing 12 and 36 months of imatinib in adjuvant therapy for gastrointestinal stromal tumors (GISTs), which demonstrated clinical benefit of longer imatinib treatment in terms of delaying recurrences and improving overall survival, both the US Food and Drug Administration and the European Medicines Agency have updated their recommendations and approved 36 months of imatinib treatment in patients with v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT)-positive GISTs (also known as CD117-positive GISTs) at high risk of recurrence after surgical resection of a primary tumor. This article discusses patient selection criteria for extended adjuvant therapy with imatinib, different classifications of risk of recurrence, and assessment of the response to therapy.

Efficacy of sorafenib in patients with gastrointestinal stromal tumors in the third- or fourth-line treatment: A retrospective multicenter experience

Sorafenib is a multi-targeted tyrosine kinase receptor inhibitor used to treat patients with advanced gastrointestinal stromal tumors (GISTs). The present study evaluated the efficacy and tolerability of sorafenib therapy for patients with GISTs. Between January 2001 and November 2012, 25 patients, from multiple centers, who had received sorafenib as the third- or fourth-line treatment for GISTs were investigated retrospectively. In total, 17 patients were male and eight were female. The median age was 54.0 years (range, 16–82 years). From the patients, 21 received imatinib for longer than six months and four received it for less than six months. The clinical benefit rate of sorafenib was 40.0%. Treatment-related adverse events were reported in 72% of patients. These adverse events were generally mild to moderate in intensity. The median progression-free survival (PFS) and overall survival (OS) times of the patients who received sorafenib were 7.2 and 15.2 months, respectively. The duration of imatinib usage was an independent prognostic factor for PFS and OS. Sorafenib is an effective treatment in patients with GISTs showing a clinical benefit rate of 40.0% and an acceptable tolerability.

Neoadjuvant imatinib in locally advanced gastrointestinal stromal tumors (GIST): the EORTC STBSG experience

BACKGROUND

Preoperative imatinib therapy of locally advanced GIST may facilitate resection and decrease morbidity of the procedure.

METHODS

We have pooled databases from 10 EORTC STBSG sarcoma centers and analyzed disease-free survival (DFS) and disease-specific survival (DSS) in 161 patients with locally advanced, nonmetastatic GISTs who received neoadjuvant imatinib. OS was calculated from start of imatinib therapy for locally advanced disease until death or last follow-up (FU) after resection of the GIST. DFS was calculated from date of resection to date of disease recurrence or last FU. Median FU time was 46 months.

RESULTS

The primary tumor was located in the stomach (55%), followed by rectum (20%), duodenum (10%), ileum/jejunum/other (11%), and esophagus (3%). The tumor resection after preoperative imatinib (median time on therapy, 40 weeks) was R0 in 83%. Only two patients have demonstrated disease progression during neoadjuvant therapy. Five-year DSS/DFS rates were 95/65%, respectively, median OS was 104 months, and median DFS was not reached. There were 56% of patients who continued imatinib after resection. Thirty-seven GIST recurrences were diagnosed (only 5 local relapses). The most common mutations affected exon 11 KIT (65%). Poorer DFS was related to primary tumor location in small bowel and lack of postoperative therapy with imatinib.

CONCLUSIONS

Our analysis comprising the largest group of GIST patients treated with neoadjuvant imatinib in routine practice indicates excellent long-term results of combined therapy in locally advanced GISTs.

Gastrointestinal stromal tumours can express CD10 and epithelial membrane antigen but not oestrogen receptor or HMB45

AIMS

Gastrointestinal stromal tumour (GIST) may share morphological and/or immunohistochemical features with various intra-abdominal neoplasms, including endometrial stromal sarcoma, perivascular epithelioid cell tumour (PEComa), melanoma and synovial sarcoma. Each of these various neoplasms has characteristic immunohistochemical markers, including epithelial membrane antigen (EMA), CD10, oestrogen receptor alpha (ERa) and/or HMB45, and therefore the primary aim of this study was to determine whether these markers are also expressed by GISTs.

METHODS AND RESULTS

Standard size sections of 52 GISTs were immunostained for EMA, CD10, ERa and a melanoma marker cocktail (targeting HMB45 and melan-A). Ten GISTs (19%) showed CD10 immunopositivity. This positivity was confined almost completely to small intestinal GISTs, and was seen among spindle cell GISTs but not epithelioid or mixed cell-type GISTs. Five of the 52 GISTs (9.6%) showed EMA immunopositivity. This positivity was always focal and usually seen in a perivascular location. None of the GISTs showed immunopositivity for ERa or the melanoma marker cocktail.

CONCLUSIONS

GISTs occasionally show CD10 immunopositivity (especially small intestinal spindle cell GISTs), and infrequently show focal EMA positivity. GISTs do not show immunopositivity for ERa or HMB45.

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.

Gastrointestinal stromal tumours--an update for histopathologists

This review aims to summarize recent knowledge gained about gastrointestinal stromal tumour (GIST) of particular relevance to histopathologists. KIT and PDGFRA mutation analyses can be useful for confirming a diagnosis of GIST, but there are some diagnostic limitations to these analyses, and so immunohistochemical markers currently remain crucial to the diagnostic process. Of these markers, CD117 and Discovered on GIST 1 (DOG1) are currently the most sensitive and specific markers of GIST, and recent data appear to disprove the fear that antigen retrieval causes false-positive CD117 immunostaining. The accurate prognostication of GIST has been greatly helped by the National Institutes of Health (NIH) and Armed Forces Institute of Pathology (AFIP) classification systems, although both systems still have limitations, and the behaviours of certain GIST subgroups are less well predicted by both systems. KIT and PDGFRA mutation analyses can help to predict the response of GISTs to receptor tyrosine kinase inhibitors, and both GISTs that respond and those that show resistance to these inhibitors may show characteristic pathological changes. Some GIST subgroups (e.g. Carney syndrome and paediatric GISTs) have had recently described clinicopathological and/or molecular characteristics which may help with the diagnosis and/or treatment of these specific neoplasms.

Specificity of DOG1 (K9 clone) and protein kinase C theta (clone 27) as immunohistochemical markers of gastrointestinal stromal tumour

AIMS

DOG1 and protein kinase C (PKC) theta are both sensitive immunohistochemical markers of gastrointestinal stromal tumour (GIST). However, there are conflicting data regarding the specificity of the most commonly used PKC theta antibody (clone 27), and there are no existing data regarding the specificity of the only known commercially available DOG1 antibody (K9 clone) at the time of writing. This study's aim was to characterize the immunoreactivity patterns of both monoclonal antibodies amongst a wide range of neoplasm types including, in particular, histological mimics of GIST.

METHODS AND RESULTS

Immunohistochemistry for DOG1 and PKC theta was performed on whole tissue sections from 23 different neoplasm types (total of 125 cases). Ten of these neoplasm types showed CD117 immunopositivity. Only three (Ewing's sarcoma, glomus tumour and synovial sarcoma) of the 23 neoplasm types showed DOG1 immunopositivity, and such positivity was often focal and weak in intensity. In contrast, all but four (ganglioneuromas, leiomyomas, desmoplastic small round cell tumours and PEComa/angiomyolipomas) of the 23 neoplasm types showed PKC theta immunopositivity.

CONCLUSIONS

Compared with CD117, DOG1 (using the K9 antibody) is a more specific marker, whereas PKC theta (using the clone 27 antibody) is a considerably less specific immunohistochemical marker for GIST.

Functional features of gene expression profiles differentiating gastrointestinal stromal tumours according to KIT mutations and expression

Background

Gastrointestinal stromal tumours (GISTs) represent a heterogeneous group of tumours of mesenchymal origin characterized by gain-of-function mutations in KIT or PDGFRA of the type III receptor tyrosine kinase family. Although mutations in either receptor are thought to drive an early oncogenic event through similar pathways, two previous studies reported the mutation-specific gene expression profiles. However, their further conclusions were rather discordant. To clarify the molecular characteristics of differentially expressed genes according to GIST receptor mutations, we combined microarray-based analysis with detailed functional annotations.

Methods

Total RNA was isolated from 29 frozen gastric GISTs and processed for hybridization on GENECHIP^® HG-U133 Plus 2.0 microarrays (Affymetrix). KIT and PDGFRA were analyzed by sequencing, while related mRNA levels were analyzed by quantitative RT-PCR.

Results

Fifteen and eleven tumours possessed mutations in KIT and PDGFRA, respectively; no mutation was found in three tumours. Gene expression analysis identified no discriminative profiles associated with clinical or pathological parameters, even though expression of hundreds of genes differentiated tumour receptor mutation and expression status. Functional features of genes differentially expressed between the two groups of GISTs suggested alterations in angiogenesis and G-protein-related and calcium signalling.

Conclusion

Our study has identified novel molecular elements likely to be involved in receptor-dependent GIST development and allowed confirmation of previously published results. These elements may be potential therapeutic targets and novel markers of KIT mutation status.