IntroductionA genetic variant explaining a part of the exposure of many kinase inhibitors (KIs) is the single nucleotide polymorphism (SNP) CYP3A4*22, resulting in less CYP3A4 enzyme activity. The... Show moreIntroductionA genetic variant explaining a part of the exposure of many kinase inhibitors (KIs) is the single nucleotide polymorphism (SNP) CYP3A4*22, resulting in less CYP3A4 enzyme activity. The primary aim of this study was to investigate if the systemic exposure is non-inferior after a dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to patients without this SNP (i.e., wildtype patients) receiving the standard dose.MethodsIn this multicenter, prospective, non-inferiority study, patients were screened for the presence of CYP3A4*22. Patients with the CYP3A4*22 SNP received a 20-33% dose reduction. At steady state, a pharmacokinetic (PK) analysis was performed and compared to the PK results from wildtype patients treated with the registered dose using a two-stage individual patient data meta-analysis approach.ResultsIn total, 207 patients were included in the final analysis. The CYP3A4*22 SNP was found in 16% of the patients in the final analysis (n = 34). Most of the included patients received imatinib (37%) or pazopanib (22%) treatment. The overall geometric mean ratio (GMR) comparing the exposure of the CYP3A4*22 carriers to the exposure of the wildtype CYP3A4 patients was 0.89 (90% confidence interval: 0.77-1.03).ConclusionNon-inferiority could not be proven for dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to the registered dose in wildtype patients. Therefore, an up-front dose reduction based upon the CYP3A4*22 SNP for all KIs does not seem an eligible new way of personalized therapy. Show less
Mohammadi, M.; IJzerman, N.S.; Hollander, D. den; Bleckman, R.F.; Oosten, A.W.; Desar, I.M.E.; ... ; Gelderblom, H. 2023
BackgroundPatients with unresectable and metastasized gastrointestinal stromal tumor (GIST) experienced a remarkable improvement of progression-free survival (PFS) and overall survival (OS) after... Show moreBackgroundPatients with unresectable and metastasized gastrointestinal stromal tumor (GIST) experienced a remarkable improvement of progression-free survival (PFS) and overall survival (OS) after the introduction of imatinib. Our hypothesis is that the outcomes of treatment with imatinib are even better nowadays compared with the registration trials that were performed two decades ago. To study this, we used real-life data from a contemporary registry.MethodsA multicenter, retrospective study was performed by exploring clinical data from a prospective real-life clinical database, the Dutch GIST Registry (DGR). Patients with advanced GIST treated with first-line imatinib were included and PFS (primary outcome) and OS (secondary outcome) were analyzed. Results of our study were compared with published results of the European Organisation for Research and Treatment of Cancer (EORTC) 62005 trial, which marked the first era of imatinib in the treatment of GIST.ResultsOverall, 420 of the 435 patients treated with imatinib in the DGR had recorded response evaluation and were included in the analysis. During a median follow-up of 35.0 months (range 2.0–136.0), progression of GIST was eventually observed in 217 patients (51.2%). The DGR cohort showed a longer median PFS (33.0 months, 95% confidence interval [CI] 28.4–37.6) compared with the EORTC 62005 trial (an estimated PFS of 19.5 months). Additionally, the median OS of 68.0 months (95% CI 56.1–80.0) was longer than the exposed median OS (46.8 months) published in the long-term follow-up results of the EORTC 62005 trial (median follow-up duration 10.9 years).ConclusionThis study provides an update on outcomes of imatinib in the treatment of advanced GIST patients and demonstrates improved clinical outcomes since the first randomized studies of imatinib 2 decades ago. Furthermore, these results represent outcomes in real-world clinical practice and can serve as a reference when evaluating effectiveness of imatinib in patients with advanced GIST. Show less
Bleckman, R.F.; Roets, E.; IJzerman, N.S.; Mohammadi, M.; Bonenkamp, H.J.J.; Gelderblom, H.; ... ; Etten, B. van 2023
Background and objectivesPrevious literature showed a high risk of recurrence following surgical treatment in patients with gastrointestinal stromal tumours (GISTs). However, little is known about... Show moreBackground and objectivesPrevious literature showed a high risk of recurrence following surgical treatment in patients with gastrointestinal stromal tumours (GISTs). However, little is known about the patient- and treatment characteristics of local recurrences (LRs) in GIST patients. Therefore, this study aimed to better understand patterns of LR in surgically treated localised GIST and to describe treatment options based on our Dutch GIST Registry (DGR).MethodsData of primary surgically treated localised GIST between January 2009 until July 2021 were retrospectively retrieved from the DGR.ResultsOf 1452 patients registered in the DGR, 912 patients were included in this study. Only 3.8% (35/912) of patients developed LR, including 20 patients with LR only and 15 patients with simultaneous LR and distant metastases (DM). Median time to LR was 30 (interquartile range 8–53) months from date of surgery. Eleven percent (100/912) of patients developed only DM. A total of 2.3% (6/259) of patients treated with adjuvant treatment developed an LR during adjuvant therapy. Seventy percent of patients with LR only (14/20) were treated with surgery (85.7% R0), which was mostly combined with systemic treatment.ConclusionsPatients with primary surgically treated localised GIST have a limited risk of developing recurrence. Fifteen percent developed recurrence, of which one quarter developed an LR. Therefore, less intensified follow-up schedules could be considered, especially during treatment with adjuvant imatinib. In patients with LR only, potentially curative treatment strategies, including surgical (re-)resection, are often possible as treatment for LR. Show less
IJzerman, N.S.; Werkhoven, E. van; Mohammadi, M.; Hollander, D. den; Bleckman, R.F.; Reyners, A.K.L.; ... ; Graaf, W.T.A. van der 2022
Background: Sex differences in cancer have gained attention in recent years. The role of sex as a prognostic factor in gastrointestinal stromal tumours (GIST) has not been well established. The aim... Show moreBackground: Sex differences in cancer have gained attention in recent years. The role of sex as a prognostic factor in gastrointestinal stromal tumours (GIST) has not been well established. The aim of this research was to elucidate potential sex differences in GIST patients and the influence of sex on disease-specific survival (DSS). Methods: A review of the literature was carried out to obtain an overview of all literature with sex as a covariate on GIST survival analyses. Furthermore, in the Dutch GIST Registry, GIST characteristics between males and females were compared and the influence of sex on DSS was analysed. Results: A total of 118 articles from the review of the literature met our selection criteria; 58% of the articles found no sex difference in survival and 42% did find a sex difference. All differences favoured female patients, although there was substantial overlap of individual patients in the various reported groups. The Dutch GIST Registry cohort consisted of 1425 patients (46% female). Compared with female patients, male patients had larger tumours (mean 9.0 cm versus 7.9 cm) and higher mitotic rates (34.4% versus 28.0% > 5 mitoses/5 mm(2)). GIST in males was more often metastasized at diagnosis (21.3% versus 13.7%) and incurable (38.5% versus 31.0%). Male patients less often received surgery of the primary tumour (71.7% versus 78.9%), but did experience more tumour ruptures (18.2% versus 13.3%). Male patients had a worse DSS than females. This was not statistically significant when corrected for differences in GIST characteristics. Conclusions: In case of sex differences in GIST in the literature, male patients have a worse outcome. In our Dutch GIST cohort a similar finding was made, but sex was shown not to be an independent factor. Male patients more often had aggressive GISTs, with larger tumours, higher mitotic rates, more tumour ruptures, and metastases, which could explain the sex differences in DSS. Show less
Purpose: The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9-mutated gastrointestinal stromal tumors (GIST) is not established.... Show morePurpose: The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9-mutated gastrointestinal stromal tumors (GIST) is not established. Here, the association of dose and other clinicopatho-logic variables with survival was evaluated in a large multi-institutional European cohort.Experimental Design: Data from 185 patients were retrospec-tively collected in 23 European GIST reference centers. Propen-sity score matching (PSM) and inverse-probability of treatment weighting (IPTW) were used to account for confounders. Uni-variate and multivariate unweighted and weighted Cox propor-tional hazard regression models were estimated for relapse-free survival (RFS), modified-RFS (mRFS) and imatinib failure-free survival (IFFS). Univariate Cox models were estimated for overall survival.Results: Of the 185 patients, 131 (70.8%) received a starting dose of 400 mg/d and the remaining 54 (29.2%) a dose of 800 mg/d. Baseline characteristics were partially unbalanced, suggesting a potential selection bias. PSM and IPTW analyses showed no advantage of imatinib 800 mg/d. In the weighted multivariate Cox models, high-dose imatinib was not associated with the survival outcomes [RFS: hazard ratio (HR), 1.24; 95% confidence interval (CI), 0.79-1.94; mRFS: HR, 1.69; 95% CI, 0.92-3.10; IFFS: HR, 1.35; 95% CI, 0.79- 2.28]. The variables consistently associated with worse survival out-comes were high mitotic index and nongastric tumor location.Conclusions: In this retrospective series of patients with KIT exon 9-mutated GIST treated with adjuvant imatinib, a daily dose of 800 mg versus 400 mg did not show better results in terms of survival outcomes. Prospective evaluation of the more appropriate adjuvant treatment in this setting is warranted. Show less
Farag, S.; IJzerman, N.S.; Houdijk, M.P.M.; Reyners, A.K.L.; Arens, A.I.; Grunhagen, D.J.; ... ; Geus-Oei, L.F. de 2021
Aim The aim of this study was to investigate the impact of F-18-FDG-PET/CT on treatment decision making in metastatic gastrointestinal stromal tumor (GIST) patients.Methods This study... Show moreAim The aim of this study was to investigate the impact of F-18-FDG-PET/CT on treatment decision making in metastatic gastrointestinal stromal tumor (GIST) patients.Methods This study retrospectively evaluated F-18-FDG-PET/CT scans to monitor response of metastatic GIST patients treated with palliative intent. Data from the Dutch GIST Registry was used. Early scans (< 10 weeks after start of treatment) and late scans (> 10 weeks after start of treatment) were scored on the impact in change of treatment.Results Sixty-one PET/CTscans were performed for treatment evaluation in 39 patients with metastatic GIST of which 36 were early scans and 25 were late scans. Early PET/CT scans led to a change in management in 5.6 % of patients and late PET/CT scans led to a change in management in 56 % of patients. Change in management was more often seen after scans with lack of metabolic response (48 % vs. 11 % in scans with metabolic response, p = 0.002). Neither metabolic response nor change in treatment were more often seen in patients with KIT mutations compared to patients with non-KIT mutations (metabolic response 65 % KIT vs. 46 % non-KIT, p = 0.33, and change in management 28 % KIT vs. 21 % nonKIT, p = 0.74).Conclusion(18)F-FDG-PET/CT is not recommended for early response evaluation in an unselected patient population with metastatic GIST, since it does not influence treatment decisions. F-18-FDG- PET/ CT, however, can be useful for late response assessment, especially in case of indeterminate CT results. Show less
Purpose: The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9-mutated gastrointestinal stromal tumors (GIST) is not established.... Show morePurpose: The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9-mutated gastrointestinal stromal tumors (GIST) is not established. Here, the association of dose and other clinicopatho-logic variables with survival was evaluated in a large multi-institutional European cohort.Experimental Design: Data from 185 patients were retrospec-tively collected in 23 European GIST reference centers. Propen-sity score matching (PSM) and inverse-probability of treatment weighting (IPTW) were used to account for confounders. Uni-variate and multivariate unweighted and weighted Cox propor-tional hazard regression models were estimated for relapse-free survival (RFS), modified-RFS (mRFS) and imatinib failure-free survival (IFFS). Univariate Cox models were estimated for overall survival.Results: Of the 185 patients, 131 (70.8%) received a starting dose of 400 mg/d and the remaining 54 (29.2%) a dose of 800 mg/d. Baseline characteristics were partially unbalanced, suggesting a potential selection bias. PSM and IPTW analyses showed no advantage of imatinib 800 mg/d. In the weighted multivariate Cox models, high-dose imatinib was not associated with the survival outcomes [RFS: hazard ratio (HR), 1.24; 95% confidence interval (CI), 0.79-1.94; mRFS: HR, 1.69; 95% CI, 0.92-3.10; IFFS: HR, 1.35; 95% CI, 0.79- 2.28]. The variables consistently associated with worse survival out-comes were high mitotic index and nongastric tumor location.Conclusions: In this retrospective series of patients with KIT exon 9-mutated GIST treated with adjuvant imatinib, a daily dose of 800 mg versus 400 mg did not show better results in terms of survival outcomes. Prospective evaluation of the more appropriate adjuvant treatment in this setting is warranted. Show less
Mohammadi, M.; IJzerman, N.S.; Hohenberger, P.; Rutkowski, P.; Jones, R.L.; Martin-Broto, J.; ... ; Schrage, Y. 2021
Background: Oesophageal gastrointestinal stromal tumours (GISTs) account for <= 1% of all GISTs. Consequently, evidence to guide clinical decision-making is limited.Methods: Clinicopathological... Show moreBackground: Oesophageal gastrointestinal stromal tumours (GISTs) account for <= 1% of all GISTs. Consequently, evidence to guide clinical decision-making is limited.Methods: Clinicopathological features and outcomes in patients with primary oesophageal GIST from seven European countries were collected retrospectively.Results: Eighty-three patients were identified, and median follow up was 55.0 months. At diagnosis, 59.0% had localized disease, 25.3% locally advanced and 13.3% synchronous metastasis. A biopsy (Fine Needle aspiration n = 29, histological biopsy n = 31) was performed in 60 (72.3%) patients. The mitotic count was low (<5 mitoses/50 High Power Fields (HPF)) in 24 patients and high (>= 5 mitoses/50 HPF) in 27 patients. Fifty-one (61.4%) patients underwent surgical or endoscopic resection. The most common reasons to not perform an immediate resection (n = 31) were; unresectable or metastasized GIST, performance status/comorbidity, patient refusal or ongoing neo-adjuvant therapy. The type of resections were enucleation (n = 11), segmental resection (n = 6) and oesophagectomy with gastric conduit reconstruction (n = 33), with median tumour size of 3.3 cm, 4.5 cm and 7.7 cm, respectively. In patients treated with enucleation 18.2% developed recurrent disease. The recurrence rate in patients treated with segmental resection was 16.7% and in patients undergoing oesophagectomy with gastric conduit reconstruction 36.4%. Larger tumours (>= 4.0 cm) and high (>5/5hpf) mitotic count were associated with worse disease free survival.Conclusion: Based on the current study, enucleation can be recommended for oesophageal GIST smaller than 4 cm, while oesophagectomy should be preserved for larger tumours. Patients with larger tumours (>4 cm) and/or high mitotic count should be treated with adjuvant therapy. (C) 2021 The Author(s). Published by Elsevier Ltd. Show less
Mohammadi, M.; IJzerman, N.S.; Hohenberger, P.; Rutkowski, P.; Jones, R.L.; Martin-Broto, J.; ... ; Schrage, Y. 2021
Background: Oesophageal gastrointestinal stromal tumours (GISTs) account for <= 1% of all GISTs. Consequently, evidence to guide clinical decision-making is limited.Methods: Clinicopathological... Show moreBackground: Oesophageal gastrointestinal stromal tumours (GISTs) account for <= 1% of all GISTs. Consequently, evidence to guide clinical decision-making is limited.Methods: Clinicopathological features and outcomes in patients with primary oesophageal GIST from seven European countries were collected retrospectively.Results: Eighty-three patients were identified, and median follow up was 55.0 months. At diagnosis, 59.0% had localized disease, 25.3% locally advanced and 13.3% synchronous metastasis. A biopsy (Fine Needle aspiration n = 29, histological biopsy n = 31) was performed in 60 (72.3%) patients. The mitotic count was low (<5 mitoses/50 High Power Fields (HPF)) in 24 patients and high (>= 5 mitoses/50 HPF) in 27 patients. Fifty-one (61.4%) patients underwent surgical or endoscopic resection. The most common reasons to not perform an immediate resection (n = 31) were; unresectable or metastasized GIST, performance status/comorbidity, patient refusal or ongoing neo-adjuvant therapy. The type of resections were enucleation (n = 11), segmental resection (n = 6) and oesophagectomy with gastric conduit reconstruction (n = 33), with median tumour size of 3.3 cm, 4.5 cm and 7.7 cm, respectively. In patients treated with enucleation 18.2% developed recurrent disease. The recurrence rate in patients treated with segmental resection was 16.7% and in patients undergoing oesophagectomy with gastric conduit reconstruction 36.4%. Larger tumours (>= 4.0 cm) and high (>5/5hpf) mitotic count were associated with worse disease free survival.Conclusion: Based on the current study, enucleation can be recommended for oesophageal GIST smaller than 4 cm, while oesophagectomy should be preserved for larger tumours. Patients with larger tumours (>4 cm) and/or high mitotic count should be treated with adjuvant therapy. (C) 2021 The Author(s). Published by Elsevier Ltd. Show less
IJzerman, N.S.; Mohammadi, M.; Tzanis, D.; Gelderblom, H.; Fiore, M.; Fumagalli, E.; ... ; Smith, M. 2020
Background: Rectal gastrointestinal stromal tumours (GISTs) are rare tumours. Variability in the managementmay influence outcome, but there is a lack of understanding regarding contemporary... Show moreBackground: Rectal gastrointestinal stromal tumours (GISTs) are rare tumours. Variability in the managementmay influence outcome, but there is a lack of understanding regarding contemporary variancein care. A multicenter, international, retrospective cohort study was performed to elucidate characteristicsand outcomes of rectal GIST in European practice, with particular reference to surgical approach.Methods: All rectal GIST patients diagnosed between 2009 and 2018 were identified from five Europeandatabases. Recurrence free survival (RFS) and overall survival (OS) were estimated using Kaplan-Meiermethod. Possible confounders were identified using Cox regression analyses.Results: From 210 patients, 155 patients had surgery. The three main types of surgery were local tumourresection (LTR, n ¼ 46), low anterior resection (LAR, n ¼ 31) and abdomino-perineal resection (APR,n ¼ 32). Most patients received neoadjuvant (65%) and/or adjuvant imatinib therapy (66%). Localrecurrence rate after surgery was 15% and overall recurrence rate 28%. No significant differences werefound in terms of RFS nor OS between LTR, LAR and APR. However, locally resected tumours weresmaller, while LAR and APR patients more often received perioperative imatinib. General hospitalstreated smaller GISTs, offered imatinib less frequently, and had a higher tumour rupture rate. In the multivariate analysis in the group having LTR, APR or LAR, the only significant prognostic factor for localrecurrence was higher age (HR 1.06, CI 1.00e1.12, p ¼ 0.048).Conclusions: In European clinical practice for rectal GIST, LTR, LAR and APR have comparable localcontrol. Multimodal approach is higher and tumour rupture less frequent in specialist centres comparedto general hospitals. Show less
IJzerman, N.S.; Mohammadi, M.; Tzanis, D.; Gelderblom, H.; Fiore, M.; Fumagalli, E.; ... ; Smith, M. 2020
Background: Rectal gastrointestinal stromal tumours (GISTS) are rare tumours. Variability in the management may influence outcome, but there is a lack of understanding regarding contemporary... Show moreBackground: Rectal gastrointestinal stromal tumours (GISTS) are rare tumours. Variability in the management may influence outcome, but there is a lack of understanding regarding contemporary variance in care. A multicenter, international, retrospective cohort study was performed to elucidate characteristics and outcomes of rectal GIST in European practice, with particular reference to surgical approach.Methods: All rectal GIST patients diagnosed between 2009 and 2018 were identified from five European databases. Recurrence free survival (RFS) and overall survival (OS) were estimated using Kaplan-Meier method. Possible confounders were identified using Cox regression analyses.Results: From 210 patients, 155 patients had surgery. The three main types of surgery were local tumour resection (LTR, n = 46), low anterior resection (LAR, n = 31) and abdomino-perineal resection (APR, n = 32). Most patients received neoadjuvant (65%) and/or adjuvant imatinib therapy (66%). Local recurrence rate after surgery was 15% and overall recurrence rate 28%. No significant differences were found in terms of RFS nor OS between LTR, LAR and APR. However, locally resected tumours were smaller, while LAR and APR patients more often received perioperative imatinib. General hospitals treated smaller GISTS, offered imatinib less frequently, and had a higher tumour rupture rate. In the multivariate analysis in the group having LTR, APR or LAR, the only significant prognostic factor for local recurrence was higher age (HR 1.06, CI 1.00-1.12, p = 0.048).Conclusions: In European clinical practice for rectal GIST, LTR, LAR and APR have comparable local control. Multimodal approach is higher and tumour rupture less frequent in specialist centres compared to general hospitals. (C) 2020 Elsevier Ltd, BASO similar to The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved. Show less
IJzerman, N.S.; Drabbe, C.; Hollander, D. den; Mohammadi, M.; H. van boven; Desar, I.M.E.; ... ; Graaf, W.T.A. van der 2020
Gastrointestinal stromal tumour (GIST) is a disease of older adults and is dominated by KIT/PDGFR mutations. In children, GIST is rare, predominantly occurs in girls, has a stomach location and... Show moreGastrointestinal stromal tumour (GIST) is a disease of older adults and is dominated by KIT/PDGFR mutations. In children, GIST is rare, predominantly occurs in girls, has a stomach location and generally lacks KIT/PDGFR mutations. For young adults (YA), aged 18 to 40 years, the typical phenotypic and genotypic patterns are unknown. We therefore aimed to describe the clinical, pathological and molecular characteristics of GIST in in YA. YA GIST patients registered in the Dutch GIST Registry (DGR) were included, and data were compared to those of older adults (OA). From 1010 patients in the DGR, 52 patients were YA (54% male). Main tumour locations were stomach (46%) and small intestine (46%). GIST genetic profiles were mutations in KIT (69%), PDGFRA (6%), SDH deficient (8%), NF1 associated (4%), ETV6-NTRK3 gene fusion (2%) or wildtype (10%). Statistically significant differences were found between the OA and YA patients (localisation, syndromic and mutational status). YA presented more often than OA in an emergency setting (18% vs. 9%). The overall five-year survival rate was 85%. In conclusion, YA GISTs are not similar to typical adult GISTs and also differ from paediatric GISTs, as described in the literature. In this series, we found a relatively high percentage of small intestine GIST, emergency presentation, 25% non-KIT/PDGFRA mutations and a relatively good survival. Show less
