Background: Acquired resistance to approved tyrosine kinase inhibitors limits their clinical use in patients with gastrointestinal stromal tumor (GIST). This study investigated the safety,... Show moreBackground: Acquired resistance to approved tyrosine kinase inhibitors limits their clinical use in patients with gastrointestinal stromal tumor (GIST). This study investigated the safety, tolerability and efficacy of alpelisib, a phosphatidylinositol 3-kinase inhibitor, used in combination with imatinib in patients with advanced GIST who had failed prior therapy with both imatinib and sunitinib. Methods: This phase 1b, multicenter, open-label study consisted of 2 phases: dose escalation and dose expansion. Dose escalation involved 200 mg once daily (QD) alpelisib, initially, followed by 250 and 350 mg. These were combined with 400 mg QD imatinib until maximum tolerated dose (MTD) and/or a recommended phase 2 dose (RP2D) of alpelisib in combination with imatinib was determined. This MTD/RP2D dose was tested to evaluate the clinical activity of this combination in dose expansion. Results: Fifty-six patients were enrolled, 21 and 35 in the dose escalation and expansion phases, respectively. The MTD of alpelisib given with imatinib was determined as 350 mg QD. Combination treatment showed partial response in 1 (2.9%) and stable disease in 15 (42.9%) patients. Median progression-free survival was 2 months (95% CI 1.8-4.6). Overall, 92.9% patients had adverse events (AEs) while 46.4% had grade 3/4 AEs, hyperglycemia being the most common (23.2%). Conclusions: The MTD of alpelisib was estimated as 350 mg QD when used in combination with imatinib 400 mg QD after oral administration in patients with advanced GIST. The safety and tolerability profile of this combination was acceptable; however, the combination did not demonstrate sufficient clinical activity to justify additional clinical testing. Show less
Background Molecular analysis of KIT and PDGFRA is critical for tyrosine kinase inhibitor treatment selection of gastrointestinal stromal tumors (GISTs) and hence recommended by international... Show moreBackground Molecular analysis of KIT and PDGFRA is critical for tyrosine kinase inhibitor treatment selection of gastrointestinal stromal tumors (GISTs) and hence recommended by international guidelines. We performed a nationwide study into the application of predictive mutation testing in GIST patients and its impact on targeted treatment decisions in clinical practice. Methods Real-world clinical and pathology information was obtained from GIST patients with initial diagnosis in 2017-2018 through database linkage between the Netherlands Cancer Registry and the nationwide Dutch Pathology Registry. Results Predictive mutation analysis was performed in 89% of the patients with high risk or metastatic disease. Molecular testing rates were higher for patients treated in expertise centers (96%) compared to non-expertise centers (75%, P < 0.01). Imatinib therapy was applied in 81% of the patients with high risk or metastatic disease without patient's refusal or adverse characteristics, e.g., comorbidities or resistance mutations. Mutation analysis that was performed in 97% of these imatinib-treated cases, did not guarantee mutation-tailored treatment: 2% of these patients had the PDGFRA p.D842V resistance mutation and 7% initiated imatinib therapy at the normal instead of high dose despite of having a KIT exon 9 mutation. Conclusion In conclusion, nationwide real-world data show that over 81% of the eligible high risk or metastatic disease patients receive targeted therapy, which was tailored to the mutation status as recommended in guidelines in 88% of cases. Therefore, still 27% of these GIST patients misses out on mutation-tailored treatment. The reasons for suboptimal uptake of testing and treatment require further study. Show less
INTRODUCTION AND IMPORTANCE: Gastrointestinal stromal tumors are the most prevalent mesenchymal tumors of the gastrointestinal tract. Distant metastases are most often found in the liver or... Show moreINTRODUCTION AND IMPORTANCE: Gastrointestinal stromal tumors are the most prevalent mesenchymal tumors of the gastrointestinal tract. Distant metastases are most often found in the liver or peritoneum with surgery being the preferred treatment option. In our center, fluorescence-guided surgery with indocyanine green is used as standard-of-care for hepatic metastases in colorectal cancer. This case report describes fluorescence-guided metastasectomy for a hepatic gastrointestinal stromal tumor in two patients undergoing open liver resection and radiofrequency ablation.CASE PRESENTATION: A 69-year old women was seen during follow-up after laparoscopic resection of a GIST in the lesser curvature of the stomach. Contrast-enhanced computed tomography imaging showed two suspicious lesions in liver segment VI and VIII. Intraoperative near-infrared fluorescence imaging of the liver clearly revealed the lesion in segment VIII, and an additional lesion in segment V - which was not seen on preoperative CT-imaging, neither on intraoperative ultrasonography. The lesion in segment VI was not seen with NIRF imaging due to its deeper location in the liver parenchyma. The second case is an 82-year old man who was also diagnosed with liver metastases from a GIST in the stomach and was scheduled for near-infrared fluorescence-guided liver resection and radio frequency ablation.CLINICAL DISCUSSION: In this case report we demonstrated the feasibility of fluorescence-guided surgery in detection of liver metastases and treatment planning of two patients with hepatic GIST metastases using indocyanine green.CONCLUSION: NIRF-imaging with ICG is useful for identification of preoperatively discovered lesions, surgical resection planning and margin evaluation, and for detection of additional hepatic GIST metastases. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of IJS Publishing Group Ltd. This is an open access article under the CC BY-NC-ND license (http://creative commons.org/licenses/by-nc-nd/4.0/). Show less
Gastrointestinal stromal tumor (GIST) is a rare mesenchymal malignancy in the gastrointestinal tract. Since the introduction of imatinib in 2002, a tyrosine kinase inhibitor (TKI) that targets Bcr... Show moreGastrointestinal stromal tumor (GIST) is a rare mesenchymal malignancy in the gastrointestinal tract. Since the introduction of imatinib in 2002, a tyrosine kinase inhibitor (TKI) that targets Bcr-Abl, KIT and PDGFR, treatment of patients with advanced GIST has been spectacularly improved. In this rapidly evolving field, more insight is needed the treatment and follow-up of GIST patients. The focus for this thesis is on treatment strategies and follow-up in GIST patients in daily clinical practice using a large comprehensive multicenter database. Show less
