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Background: The added value of tumoural genomic profiles to conventional clinico-biological factors to predict progression-free survival (PFS) and overall survival (OS) was prospectively investigated in patients with advanced gastrointestinal stromal tumours (GIST) treated in the BFR14 study., Methods: Of the 434 included patients, mutational analysis was performed in 322 patients. Survival analysis was performed in patients with validated mutational status., Results: Mutational status was validated in 228 patients. We identified 196 patients with tumours harbouring 200 KIT alterations (exon 11: 173 patients, exon 9: 22 patients, exon 17: 3 patients, exon 13: 2 patients; 4 patients had double KIT mutations), 6 patients with PDGFRA mutations and 26 patients with wild-type (WT) GIST genotype. On a median follow-up of 73 months, median PFS/OS were 12.3/54.9 months for WT GIST, 12.6/55 months for KIT exon 9, and 39.4 months/not reached (69.1% at 5 years) for KIT exon 11. Tumour size, female gender, KIT exon 11 mutations and CD34 positivity were independent prognostic factors for a higher PFS. A higher OS was predicted by performance status (PS) <2, low neutrophil and normal lymphocyte counts, KIT exon 11 mutations, non-advanced tumour and female gender. KIT exon 11 mutations at codons 557-558 showed better tumour response (p=0.028) but shorter PFS (p=0.0176)., Conclusions: In GIST patients, presence of a KIT exon 11 mutation is an independent prognostic factor for PFS and OS, along with gender, PS, tumour size, lymphocyte and neutrophil counts. Subsets of exon 11 mutations are associated with significantly different response patterns and PFS., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Masitinib is a highly selective tyrosine kinase inhibitor with activity against the main oncogenic drivers of gastrointestinal stromal tumor (GIST). Masitinib was evaluated in patients with advanced GIST after imatinib failure or intolerance., Patients and Methods: Prospective, multicenter, randomized, open-label trial. Patients with inoperable, advanced imatinib-resistant GIST were randomized (1 : 1) to receive masitinib (12 mg/kg/day) or sunitinib (50 mg/day 4-weeks-on/2-weeks-off) until progression, intolerance, or refusal. Primary efficacy analysis was noncomparative, testing whether masitinib attained a median progression-free survival (PFS) (blind centrally reviewed RECIST) threshold of >3 months according to the lower bound of the 90% unilateral confidence interval (CI). Secondary analyses on overall survival (OS) and PFS were comparative with results presented according to a two-sided 95% CI., Results: Forty-four patients were randomized to receive masitinib (n = 23) or sunitinib (n = 21). Median follow-up was 14 months. Patients receiving masitinib experienced less toxicity than those receiving sunitinib, with significantly lower occurrence of severe adverse events (52% versus 91%, respectively, P = 0.008). Median PFS (central RECIST) for the noncomparative primary analysis in the masitinib treatment arm was 3.71 months (90% CI 3.65). Secondary analyses showed that median OS was significantly longer for patients receiving masitinib followed by post-progression addition of sunitinib when compared against patients treated directly with sunitinib in second-line [hazard ratio (HR) = 0.27, 95% CI 0.09-0.85, P = 0.016]. This improvement was sustainable as evidenced by 26-month follow-up OS data (HR = 0.40, 95% CI 0.16-0.96, P = 0.033); an additional 12.4 months survival advantage being reported for the masitinib treatment arm. Risk of progression while under treatment with masitinib was in the same range as for sunitinib (HR = 1.1, 95% CI 0.6-2.2, P = 0.833)., Conclusions: Primary efficacy analysis ensured the masitinib treatment arm could satisfy a prespecified PFS threshold. Secondary efficacy analysis showed that masitinib followed by the standard of care generated a statistically significant survival benefit over standard of care. Encouraging median OS and safety data from this well-controlled and appropriately designed randomized trial indicate a positive benefit-risk ratio. Further development of masitinib in imatinib-resistant/intolerant patients with advanced GIST is warranted., (© The Author 2014. Published by Oxford University Press on behalf of the European Society for Medical Oncology.)

Purpose: This study was designed to assess the role of radiofrequency ablation (RFA) in the multimodality management of gastrointestinal stromal tumors (GIST) in patients undergoing targeted tyrosine kinase inhibitor therapy (TKI) for liver metastases., Methods: Outcomes of 17 patients who underwent liver RFA for 27 metastatic GIST after TKI therapy, from January 2004 to March 2012, were retrospectively analyzed. Mean maximum tumor diameter was 2.5 ± 1 cm (range 0.9-4.5 cm). In seven patients (group A), RFA of all residual tumors was performed, with curative intent, and TKI therapy was discontinued. In five patients (group B), RFA of all residual tumors was performed upon achieving the best morphological response with TKI therapy, which was maintained after RFA. In another five patients (group C), RFA was performed on individual liver metastases which were progressive under TKI therapy., Results: All 27 targeted tumors were completely ablated, without local recurrence during the mean follow-up period of 49 months. No major complications occurred. Two minor complications were reported (11 %). Only two patients (both in group C) died at 20 and 48 months. Two-year progression-free survival (PFS) after RFA was 29 % in group A, 75 % in group B, and 20 % in group C., Conclusions: RFA in patients, previously treated with TKI, is feasible and safe. Our data suggest that RFA is a useful therapeutic option in patients with metastatic GIST and should be performed at the time of best clinical response with patient maintained under TKI after the procedure.

Background: We previously demonstrated that interruption of imatinib mesylate (IM) in responding patients (pts) with advanced gastrointestinal stromal tumours (GISTs) results in rapid reprogression. The impact of interruption on residual tumour, quality of response and secondary resistance has not been fully investigated., Patients and Methods: Within the BRF14 study, 71 non-progressing patients were randomly assigned in the interruption arms after 1, 3 or 5 years. IM was resumed in the case of progressive disease (PD). Tumour status at randomisation, relapse and after IM rechallenge, progression-free survival (PFS) and time to secondary resistance were analysed., Results: At data cut-off, 51 of 71 patients had restarted IM following documented PD. Eighteen patients (35%) progressed on known lesions only, while 33 patients (65%) had new lesions, with concomitant progression of known lesions in 17 patients. Only 8 (42%) of complete remission (CR) patients and 12 (52%) of partial response (PR) patients at randomisation achieved a new CR and PR. Patients progressing rapidly after interruption had a poorer prognosis. Tumour status at randomisation influenced time to progression after rechallenge., Conclusion: In advanced GIST patients interrupting IM, quality of response upon reintroduction did not reach the tumour status observed at randomisation. Rapid progression after imatinib interruption is associated with poor PFS after reintroduction.

Background: Masitinib is a tyrosine kinase inhibitor with greater in vitro activity and selectivity for the wild-type c-Kit receptor and its juxtamembrane mutation than imatinib, without inhibiting kinases of known toxicities. This phase II study evaluated masitinib as a first-line treatment of advanced GIST., Patients and Methods: Imatinib-naïve patients with advanced GIST received oral masitinib at 7.5mg/kg/d. Efficacy end-points included response rate (RR) at 2 months, best response according to RECIST, metabolic response rate, disease control rate (DCR), progression-free survival (PFS) and overall survival rate (OS)., Results: Thirty patients were enrolled with a median follow-up of 34 months. The most frequent grade 3-4 toxicities were rash (10%) and neutropaenia (7%). Two patients withdrew due to treatment-related adverse events. At 2 months, RR was 20% according to response evaluation criteria in solid tumours (RECIST) and 86% according to FDG-PET response criteria. Best responses were a complete response in 1/30 patient (3.3%), partial response in 15/30 patients (50%), stable disease in 13/30 patients (43.3%) and progressive disease in 1/30 patient (3.3%); (DCR: 96.7%). Median time-to-response was 5.6 months (0.8-23.8 months). Estimated median PFS was 41.3 months with PFS rate of 59.7% [37.9; 76.0] and 55.4 [33.9; 72.5] at 2 and 3 years, respectively. The OS at 2 and 3 years was stable at 89.9% [71.8; 96.6]., Conclusions: Masitinib appears to be effective as a first-line treatment of advanced GIST with comparable results to imatinib in terms of safety and response. PFS and in particular OS data show promise that masitinib may provide sustainable benefits. There is sufficient compelling evidence to warrant a phase III clinical trial., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Imatinib has revolutionized the treatment and prognosis of patients with gastrointestinal stromal tumors (GIST). In contrast to liver and/or abdominal involvement, bone metastases are an uncommon event in GIST. We report here two patients with metastatic GIST who developed pelvic bone marrow focal lesions visible on MRI examinations, while Imatinib dramatically improved other tumor sites. A biopsy in one patient diagnosed bone marrow necrosis. The other patient had a favorable follow-up over several years, without bone metastases. Focal bone marrow abnormalities, detected on MRI examinations and mimicking bone metastases in patients who were otherwise responding, should be considered as probable bone marrow necrosis.

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