Long-Term Efficacy of High-Dose Imatinib in Hispanic Patients Without Access to Second-Generation Tyrosine Kinase Inhibitors Treated in LATAM Centers.

BACKGROUND: While second-generation tyrosine kinase inhibitors (TKI) revolutionized treatment for patients with chronic myeloid leukemia (CML) who developed a suboptimal response to imatinib, many patients in developing countries are fixed to the latter due to socioeconomic barriers. Despite this scenario, scarce information is available to evaluate the clinical prognosis of these patients. METHODS: We conducted a retrospective cohort analysis to compare the overall mortality of patients with CML who developed a suboptimal response to a standard dose of imatinib and were treated with either high-dose imatinib or a second-generation TKI. We created a marginal structural model with inverse probability weighting and stabilized weights. Our primary outcome was overall survival (OS) at 150 months. Our secondary outcomes were disease-free survival (DFS) at 150 months and adverse events. RESULTS: The cohort included 148 patients, of which 32 received high-dose imatinib and 116 a second-generation TKI. No difference was found in the 150-month overall survival risk (RR: 95% CI 0.91, 0.55-1.95, P-value = .77; RD: -0.04, -0.3 to 0.21, P-value = .78) and disease-free survival (RR: 1.02, 95% CI 0.53-2.71, P-value = .96; RD: 0.01, -0.26 to 0.22, P-value = .96). There was also no difference in the incidence of adverse events in either group. CONCLUSION: Ideally, patients who develop a suboptimal response to imatinib should be switched to a second-generation TKI. If impossible, however, our findings suggest that patients treated with high-dose imatinib have a similar overall survival and disease-free survival prognosis to patients receiving a second-generation TKI.

Loss of CD22 expression and expansion of a CD22dim subpopulation in adults with relapsed/refractory B-lymphoblastic leukaemia after treatment with Inotuzumab-Ozogamicin.

Treatment options for relapsed or refractory B-lymphoblastic leukaemia (r/r B-ALL) are limited and the prognosis of these patients remains dismal, but novel immunotherapeutic options such as the anti-CD22 antibody-drug-conjugate Inotuzumab-Ozogamicin (InO) have improved outcomes in these patients. Flow cytometry is essential to assess antigen-expression prior to treatment initiation of antigen-directed immunotherapies. Here, we present flow cytometric and clinical data of three adult patients with r/r B-ALL who failed treatment with InO associated with reduced or lost antigen-expression. In addition, we present comparative data on two different diagnostic CD22-specific antibody clones that exhibit significant differences in staining intensities.

Development of Imatinib Mesylate-Loaded Liposomes for Nose to Brain Delivery: In Vitro and In Vivo Evaluation.

Neurodegenerative diseases like Alzheimer's disease require treatment where it is essential for drug to reach brain. Nose to brain delivery of drugs enables direct transport to brain bypassing blood brain barrier. Imatinib mesylate, an anti-cancer agent, was found to have potential anti-Alzheimer's activity and thus repurposed for the same. However, the drug has severe side effects, poor brain bioavailability which may hinder effective treatment of Alzheimer's disease. In the current work, imatinib mesylate-loaded liposomes were prepared with particle size below 150 nm with sustained drug release up to 96 h. The liposomal drug formulation was compared with plain drug solution for cytotoxicity on N2a cells and did not show any kind of toxicity at concentrations up to 25 µg/mL. The nanocarrier formulation was then evaluated for brain deposition by nose to brain administration in comparison with drug solution in rats. The liposomes effectively improved the brain deposition of drug in brain from formulation compared to pure drug solution as indicated by AUC from in vivo experiments. These results indicate that the nose to brain delivery of liposomal imatinib mesylate improved the drug deposition and residence time in brain compared to drug solution administered through oral and intranasal routes.

Prognostic value of skeletal muscle mass during tyrosine kinase inhibitor (TKI) therapy in cancer patients: a systematic review and meta-analysis.

Low muscle mass has been associated with worse clinical outcomes in various cancers. This work investigated whether, during tyrosine kinases inhibitors (TKIs) therapy, low muscle mass was associated with treatment toxicity and survival outcomes. A systematic literature search was performed in Pubmed, Web of Science, and Scopus databases from inception to June 2020, based on fixed inclusion and exclusion criteria. Effect sizes were estimated with hazard ratios (HR) and odds ratios (OR) with 95% confidence interval (CI) and heterogeneity was assessed by measuring inconsistency (I2) based on the Chi squared test. A total of 24 retrospective studies were identified, enrolling patients treated with sorafenib (n = 12), sunitinib (n = 6), lenvatinib (n = 3), regorafenib (n = 2), gefitinib (n = 1), imatinib (n = 1), and pazopanib (n = 1). Thirteen studies were deemed eligible for pooled analyses. Meta-analyses found a significant effect of low muscle mass on dose-limiting toxicity (DLT) (OR 2.40, 95% CI 1.26-4.58, p = 0.008, I2 = 51%) in patients treated with TKI therapy. A subgroup analysis by treatment showed an association between DLT and low muscle during sorafenib or sunitinib, although not significant. A significant association between low skeletal muscle index and poorer overall survival was observed in HCC patients treated with sorafenib (HR 1.45, 95% CI 1.07-1.96, p = 0.02). For other TKIs, although some results showed an association between low muscle mass and worse outcomes, the number of studies for each TKI therapy was too small to reach conclusions. Skeletal muscle mass could influence the prognosis of some TKI-treated patients. This effect is demonstrated in sorafenib-treated HCC patients but remains almost unexplored in other cancer patients undergoing TKI therapy. Further prospective studies with large sample size and sufficient follow-up are needed to clarify the role of muscle mass in the metabolism of TKI-based cancer treatment, and its association with toxicity and survival.

TKI dose reduction can effectively maintain major molecular remission in patients with chronic myeloid leukaemia.

Targeted therapy for chronic myeloid leukaemia (CML) has allowed for a near-normal patient life-expectancy; however, quality of life and aggravation of existing co-morbidities have posed new treatment challenges. In clinical practice, TKI dose reduction occurs frequently, often on multiple occasions, because of intolerance. We conducted a retrospective 'real-world practice' review of 246 patients receiving lower than standard dose (LD) TKI after the achievement of major molecular response (MR3), because of intolerable adverse events. In 274 of 298 cases of dose reduction (91·9%), MR3 was maintained at median follow-up of 27·3 months. One patient progressed to blast crisis while on LD TKI. Two patients developed two new ABL kinase domain mutations (T315I and V299L), of whom one had achieved deep molecular response on an alternative LD TKI at last follow-up. Seventy-six patients eventually discontinued LD TKI and the two-year treatment-free remission (TFR) rate in these patients was 74·1%. The majority of patients with CML in at least MR3 appear to be safely managed with LD TKI, although three of 246 patients had new events (progression and new mutation), indicating that this approach requires vigilance. TKI LD does not prevent the achievement of TFR in this patient population.

The effect of grape seed and green tea extracts on the pharmacokinetics of imatinib and its main metabolite, N-desmethyl imatinib, in rats.

BACKGROUND: Imatinib is mainly metabolized by CYP3A4 and to a lesser extent by other isoenzymes, with N-desmethyl imatinib being its major equipotent metabolite. Being a CYP3A4 substrate, imatinib co-administration with CYP3A4 modulators would change its pharmacokinetic profile. The cancer chemoprevention potential and anticancer efficacy of many herbal products such as grape seed (GS) and green tea (GT) extracts had led to an increase in their concomitant use with anticancer agents. GS and GT extracts were demonstrated to be potent inhibitors of CYP3A4. The aim of this study is to investigate the effect of standardized GS and/or GT extracts at two different doses on the pharmacokinetics of imatinib and its metabolite, N-desmethyl imatinib, in SD-rats. METHODS: Standardized GS and/or GT extracts were administered orally once daily for 21 days, at low (l) and high (h) doses, 50 and 100 mg/kg, respectively, before the administration of a single intragastric dose of imatinib. Plasma samples were collected and analyzed for imatinib and N-desmethyl imatinib concentrations using LC-MS/MS method, then their non-compartmental pharmacokinetic parameters were determined. RESULTS: h-GS dose significantly decreased imatinib's Cmax and the [Formula: see text] by 61.1 and 72.2%, respectively. Similar effects on N-desmethyl imatinib's exposure were observed as well, in addition to a significant increase in its clearance by 3.7-fold. l-GT caused a significant decrease in imatinib's Cmax and [Formula: see text] by 53.6 and 63.5%, respectively, with more significant effects on N-desmethyl imatinib's exposure, which exhibited a significant decrease by 79.2 and 81.1%, respectively. h-GT showed similar effects as those of l-GT on the kinetics of imatinib and its metabolite. However, when these extracts were co-administered at low doses, no significant effects were shown on the pharmacokinetics of imatinib and its metabolite. Nevertheless, increasing the dose caused a significant decrease in Cmax of N-desmethyl imatinib by 71.5%. CONCLUSIONS: These results demonstrated that the pharmacokinetics of imatinib and N-desmethyl imatinib had been significantly affected by GS and/or GT extracts, which could be partially explained by the inhibition of CYP3A-mediated metabolism. However, the involvement of other kinetic pathways such as other isoenzymes, efflux and uptake transporters could be involved and should be characterized.

Stealth Polymer-Coated Graphene Oxide Decorated Mesoporous Titania Nanoplatforms for In Vivo Chemo-Photodynamic Cancer Therapy.

PURPOSE: The goal of this study was to develop chemotherapeutic drug-loaded photoactivable stealth polymer-coated silica based- mesoporous titania nanoplatforms for enhanced antitumor activity. METHODS: Both in vitro and in vivo models of solvothermal treated photoactivable nanoplatforms were evaluated for efficient chemo-photothermal activity. A versatile nanocomposite that combined silica based- mesoporous titania nanocarriers (S-MTN) with the promising photoactivable agent, graphene oxide (G) modified with a stealth polymer (P) was fabricated to deliver chemotherapeutic agent, imatinib (I), (referred as S-MTN@IG-P) for near-infrared (NIR)-triggered drug delivery and enhanced chemo-photothermal therapy. RESULTS: The fabricated S-MTN@IG-P nanoplatform showed higher drug loading (~20%) and increased drug release (~60%) in response to light in acidic condition (pH 5.0). As prepared nanoplatform significantly converted NIR light into thermal energy (43.2°C) to produce reactive oxygen species (ROS). The pronounced cytotoxic effect was seen in both colon cancer cells (HCT-116 and HT-29) that was mediated through the chemotherapeutic effect of imatinib and the photothermal and ROS generation effects of graphene oxide. In vivo study also showed that S-MTN@IG-P could significantly accumulate into the tumor area and suppress the tumor growth under NIR irradiation without any biocompatibility issues. CONCLUSION: Cumulatively, the above results showed promising effects of S-MTN@IG-P for effective chemo-phototherapy of colon cancer.

The effects of combination treatments on drug resistance in chronic myeloid leukaemia: an evaluation of the tyrosine kinase inhibitors axitinib and asciminib.

BACKGROUND: Chronic myeloid leukaemia is in principle a treatable malignancy but drug resistance is lowering survival. Recent drug discoveries have opened up new options for drug combinations, which is a concept used in other areas for preventing drug resistance. Two of these are (I) Axitinib, which inhibits the T315I mutation of BCR-ABL1, a main source of drug resistance, and (II) Asciminib, which has been developed as an allosteric BCR-ABL1 inhibitor, targeting an entirely different binding site, and as such does not compete for binding with other drugs. These drugs offer new treatment options. METHODS: We measured the proliferation of KCL-22 cells exposed to imatinib-dasatinib, imatinib-asciminib and dasatinib-asciminib combinations and calculated combination index graphs for each case. Moreover, using the median-effect equation we calculated how much axitinib can reduce the growth advantage of T315I mutant clones in combination with available drugs. In addition, we calculated how much the total drug burden could be reduced by combinations using asciminib and other drugs, and evaluated which mutations such combinations might be sensitive to. RESULTS: Asciminib had synergistic interactions with imatinib or dasatinib in KCL-22 cells at high degrees of inhibition. Interestingly, some antagonism between asciminib and the other drugs was present at lower degrees on inhibition. Simulations revealed that asciminib may allow for dose reductions, and its complementary resistance profile could reduce the risk of mutation based resistance. Axitinib, however, had only a minor effect on T315I growth advantage. CONCLUSIONS: Given how asciminib combinations were synergistic in vitro, our modelling suggests that drug combinations involving asciminib should allow for lower total drug doses, and may result in a reduced spectrum of observed resistance mutations. On the other hand, a combination involving axitinib was not shown to be useful in countering drug resistance.

Treatment of generalized infantile myofibromatosis with sorafenib and imatinib: A case report.

Infantile myofibromatosis (IM) is characterized by solitary musculoskeletal nodules presenting during infancy but can manifest as multiple lesions with visceral involvement. Multicentric IM with visceral involvement carries a high risk of mortality and there is no consensus on treatment. We present a case of a patient with multicentric IM and pulmonary involvement who progressed on several chemotherapeutic regimens and subsequently had a complete response to sorafenib and later imatinib. This report describes the novel use of sorafenib and imatinib to treat generalized IM and the role of continued tyrosine kinase inhibitor therapy to maintain remission.

Phase I Study of Rapid Alternation of Sunitinib and Regorafenib for the Treatment of Tyrosine Kinase Inhibitor Refractory Gastrointestinal Stromal Tumors.

PURPOSE: Polyclonal emergence of KIT secondary mutations is a main mechanism of imatinib progression in gastrointestinal stromal tumor (GIST). Approved KIT inhibitors sunitinib and regorafenib have complementary activity against KIT resistance mutations. Preclinical evidence suggests that rapid alternation of sunitinib and regorafenib broadens the spectrum of imatinib-resistant subclones targeted. PATIENTS AND METHODS: Phase Ib study investigating continuous treatment with cycles of sunitinib (3 days) followed by regorafenib (4 days) in patients with tyrosine kinase inhibitor (TKI)-refractory GIST. A 3+3 dosing schema was utilized to determine the recommended phase II dose (RP2D). Plasma samples were analyzed for pharmacokinetics and circulating tumor DNA (ctDNA) studies using targeted error correction sequencing (TEC-seq) and droplet digital PCR (ddPCR). RESULTS: Of the 14 patients enrolled, 2 experienced dose-limiting toxicities at dose level 2 (asymptomatic grade 3 hypophosphatemia). Sunitinib 37.5 mg/day and regorafenib 120 mg/day was the RP2D. Treatment was well-tolerated and no unexpected toxicities resulted from the combination. Stable disease was the best response in 4 patients, and median progression-free survival was 1.9 months. Combined assessment of ctDNA with TEC-seq and ddPCR detected plasma mutations in 11 of 12 patients (92%). ctDNA studies showed that KIT secondary mutations remain the main mechanism of resistance in TKI-refractory GIST, revealing effective suppression of KIT-mutant subpopulations in patients benefiting from the combination. CONCLUSIONS: Sunitinib and regorafenib combination is feasible and tolerable. Rapid alternation of TKIs with complementary activity might be effective when combining drugs with favorable pharmacokinetics, potentially allowing active doses while minimizing adverse events. Serial monitoring with ctDNA may guide treatment in patients with GIST.

The Outcomes of Chronic Myeloid Leukemia Patients With Molecular Warning Responses During Imatinib Treatment According to the European LeukemiaNet 2013 Recommendations.

BACKGROUND: In the European LeukemiaNet (ELN) 2013 recommendations, chronic myeloid leukemia (CML) patients with warning response (WR) were suggested to be monitored closely continuing with the same tyrosine kinase inhibitor (TKI). Differently, the guidelines of the National Comprehensive Cancer Network considers switching to another TKI as an option. PATIENTS AND METHODS: We retrospectively evaluated 73 CML patients receiving first-line imatinib, who were followed and managed in accordance with ELN recommendations. We compared patients with molecular WR with patients with optimal response (OR) and failure regarding short- and long-term outcomes. RESULTS: The cumulative major molecular response (MMR) rates in patients with OR were significantly higher at any time point than those achieved by the WR group. Patients with WR at 3 months had significantly inferior failure-free survival (FFS) than optimal responders, but overall survival (OS) was similar. For 6 and 12 months, the WR and OR groups had similar FFS and OS. Twenty of 23 patients with WR at 12 months achieved MMR during imatinib treatment. CONCLUSION: It takes longer to get to ELN time points with imatinib than second-generation TKIs (2GTKIs). Treatment might fail in a small proportion of the patients with WR during imatinib treatment, but close and careful monitoring and timely switching to 2GTKIs might translate into favorable outcomes. Avoiding early switch to 2GTKIs would prevent patients from experiencing potential toxicities. There is still a need for prospective comparative studies (ie, continuing imatinib treatment vs. switching to 2GTKIs) in patients with WR, to justify the validity of this response category and to explore the benefit of treatment change in these patients.

Neferine in the Lotus Plumule Potentiates the Antitumor Effect of Imatinib in Primary Chronic Myeloid Leukemia Cells In Vitro.

Imatinib, the prototype BCR-ABL tyrosine kinase inhibitor (TKI), is the first-line treatment for Philadelphia chromosome-positive chronic myeloid leukemia (CML) in the chronic phase. However, a subgroup of patients exhibit poor response or experience relapse. This issue may be overcome by combination therapy using natural compounds. Neferine, a major bisbenzylisoquinoline alkaloid extracted from "lotus plumule" (seed embryo of lotus) commonly used in traditional Chinese medicine and tea, was used herein in the combination treatment of CML. The MTT assay showed that neferine exerted cytotoxicity in primary CML cells in a dose-dependent manner. Moreover, low concentrations of neferine (4 and 8 µM) sensitized primary CML cells to imatinib (CI < 1), and significantly decreased its IC50 from 0.70 ± 0.10 to 0.32 ± 0.06 µM and 0.16 ± 0.02 µM, respectively. Cotreatment of neferine and imatinib significantly decreased the expression of BCR-ABL protein and its molecular chaperone heat shock protein 90 (Hsp90) mRNA and protein levels, and further decreased phospho-extracellular regulated protein kinase 1/2 (p-Erk1/2) and myeloid cell leukemia (Mcl-1) expression. These results suggest that neferine might be a potential imatinib sensitizer in CML treatment. PRACTICAL APPLICATION: In China, Lotus plumule, the green embryo of lotus, is used as a tea and as a source of herbal medicine in the treatment of anxiety, insomnia, spermatorrhea, and thirst. Additional, neferine, a bisbenzylisoquinoline alkaloid extracted from lotus plumule has been shown to have antitumor potential. Herein, the effect of neferine and imatinib cotreatment on primary CML cells obtained from CML patients was assessed, with a synergistic effect being observed between the two compounds. Therefore, neferine might be a promising natural compound to potentiate imatinib in CML patients.

Adverse reactions of sorafenib, sunitinib, and imatinib in treating digestive system tumors.

BACKGROUND: This study was conducted to assess the adverse reactions caused by multi-target tyrosine kinase inhibitor treatment of gastrointestinal tumors. METHODS: We carried out a retrospective study of drug-related adverse reactions in 115 patients who were treated with sorafenib, sunitinib, and imatinib for primary hepatocellular carcinoma or gastrointestinal stromal tumors from October 2003 to March 2012 at the Peking University International Hospital. RESULTS: The total incidence of adverse reactions of sorafenib, sunitinib, and imatinib in patients with hepatocellular carcinoma and gastrointestinal stromal tumors was > 80%. The main adverse reactions of sorafenib were hypertension in 38 patients (33.3%) and diarrhea in 28 patients (24.4%). Sunitinib was associated with higher incidence and greater grade 3-4 toxicity. The common toxicities were skin color changes in 105 patients (90.9%), hand-foot skin reactions in 65 patients (54.6%), and leukopenia (63.6%), hypertension (22.7%), proteinuria (22.7%), liver function impairment (22.7%), and hypomagnesemia (27.3%). While imatinib was well tolerated, it was associated with the highest number of adverse reactions, including skin color change (55.6%) and edema (38.9%). Hypophosphatemia (4.4%) and hoarseness (2.2%) only occurred in the sorafenib treatment group. CONCLUSIONS: The adverse reactions of multi-target tyrosine kinase inhibitor treatments are generally mild to moderate, and most patients can tolerate these without the need for further intervention. Some serious adverse reactions may be alleviated by discontinuing the drugs or by administering symptomatic treatment.

Restrained management of copper level enhances the antineoplastic activity of imatinib in vitro and in vivo.

The present study was designed to investigate if elevated copper level can be targeted to enhance the efficacy of a significant anticancer drug, imatinib (ITB). The antineoplastic activity of this drug was assessed in the HepG2, HEK-293, MCF-7 and MDA-MD-231 cells targeting elevated copper level as their common drug target. The cell lines were treated with the different doses of copper chloride (Cu II) and disulfiram (DSF) alone as well as in their combinations with the drug for 24 h in standard culture medium and conditions. The treated cells were subjected to various assays including MTT, PARP, p-53, caspase-7, caspase-3, LDH and single cell electrophoresis. The study shows that DSF and Cu (II) synergizes the anticancer activity of ITB to a significant extent in a dose-specific way as evidenced by the combinations treated groups. Furthermore, the same treatment strategy was employed in cancer-induced rats in which the combinations of ITB-DSF and ITB-Cu II showed enhanced antineoplastic activity as compared to ITB alone. However, DSF was more effective than Cu (II) as an adjuvant to the drug. Hence, restrained manipulation of copper level in tumor cells can orchestrate the redox and molecular dispositions inside the cells favoring the induction of apoptosis.

Systematic review and meta-analysis of standard-dose imatinib vs. high-dose imatinib and second generation tyrosine kinase inhibitors for chronic myeloid leukemia.

PURPOSE: Most randomized clinical trials evaluating second generation tyrosine kinase inhibitors (TKI) for the first-line treatment of Chronic Myeloid Leukemia used as comparator the 'standard' dose of 400 mg imatinib daily. Several studies showed higher rates of major molecular remission (MMR) at 12 months with 800 mg compared to 400 mg, suggesting that high-dose imatinib may be the appropriate comparator rather than 400 mg. METHODS: We systematically reviewed randomized trials comparing the two dosages, calculated a common estimator and compared the result to a common estimator of trials evaluating a second generation TKI in comparison with 400 mg imatinib daily. RESULTS: We identified three trials comparing 400-800 mg imatinib resulting in a common relative risk of 1.30 (1.13-1.49) and indicating a significantly higher rate of MMR in patients treated with 800 mg imatinib (p = 0.0003). We identified five trials comparing 400 mg imatinib daily to a second generation TKI. The common relative risk for MMR at 12 months was 1.69 (1.50-1.90, p < 0.0001). Differences in the prognostic profiles precluded a direct comparison of the common efficacy estimates. CONCLUSIONS: We conclude that imatinib was probably not licensed at the optimal dose initially. We suggest that in the future, new TKIs are compared with a higher dose of imatinib. In addition, high-dose imatinib should be considered more often for routine clinical decisions based on the characteristics of the individual patient.

Cantharidin Overcomes Imatinib Resistance by Depleting BCR-ABL in Chronic Myeloid Leukemia.

Cantharidin (CTD) is an active compound isolated from the traditional Chinese medicine blister beetle and displayed anticancer properties against various types of cancer cells. However, little is known about its effect on human chronic myeloid leukemia (CML) cells, including imatinib-resistant CML cells. The objective of this study was to investigate whether CTD could overcome imatinib resistance in imatinib-resistant CML cells and to explore the possible underlying mechanisms associated with the effect. Our results showed that CTD strongly inhibited the growth of both imatinib-sensitive and imatinib-resistant CML cells. CTD induced cell cycle arrest at mitotic phase and triggered DNA damage in CML cells. The ATM/ATR inhibitor CGK733 abrogated CTD-induced mitotic arrest but promoted the cytotoxic effects of CTD. In addition, we demonstrated that CTD downregulated the expression of the BCR-ABL protein and suppressed its downstream signal transduction. Real-time quantitative PCR revealed that CTD inhibited BCR-ABL at transcriptional level. Knockdown of BCR-ABL increased the cell-killing effects of CTD in K562 cells. These findings indicated that CTD overcomes imatinib resistance through depletion of BCR-ABL. Taken together, CTD is an important new candidate agent for CML therapy.

Pazopanib plus best supportive care versus best supportive care alone in advanced gastrointestinal stromal tumours resistant to imatinib and sunitinib (PAZOGIST): a randomised, multicentre, open-label phase 2 trial.

BACKGROUND: Gastrointestinal stromal tumours (GIST) are the most common mesenchymal neoplasms of the gastrointestinal tract. Imatinib followed by sunitinib and regorafenib is the standard sequence of treatment for advanced disease. Pazopanib is effective in soft tissue sarcomas but has never been assessed in advanced GIST in a randomised trial. We aimed to assess the efficacy and safety of pazopanib in patients with previously treated advanced GIST. METHODS: In this randomised, open-label phase 2 study, we enrolled adults (aged ≥18 years) with advanced GIST resistant to imatinib and sunitinib from 12 comprehensive cancer centres or university hospitals in France and randomly assigned them 1:1 using an interactive web-based centralised platform to 800 mg oral pazopanib once daily in 4-week cycles plus best supportive care or best supportive care alone. Randomisation was stratified by the number of previous treatment regimens (2 vs ≥3); no-one was masked to treatment group allocation. Upon disease progression, patients in the best supportive care group were allowed to switch to pazopanib as compassionate treatment. The primary endpoint was investigator-assessed progression-free survival, analysed by intention-to-treat. All randomised participants who received at least one dose of pazopanib were included in the safety analysis. This study is registered with ClinicalTrials.gov, number NCT01323400. FINDINGS: Between April 12, 2011, and Dec 9, 2013, 81 patients were enrolled and randomly assigned to pazopanib plus best supportive care (n=40) or best supportive care alone (n=41). The median follow-up was 26·4 months (IQR 22·0-37·8) in the pazopanib plus best supportive care group and 28·9 months (22·0-35·2) in the best supportive care group. 4-month investigator-assessed progression-free survival was 45·2% (95% CI 29·1-60·0) in the pazopanib plus best supportive care group versus 17·6% (7·8-30·8) in the best supportive care group (hazard ratio [HR] 0·59, 95% CI 0·37-0·96; p=0·029). Median progression-free survival was 3·4 months (95% CI 2·4-5·6) with pazopanib plus best supportive care and 2·3 months (2·1-3·3) with best supportive care alone (HR 0·59 [0·37-0·96], p=0·03). 36 (88%) of the patients originally assigned to the best supportive care group switched to pazopanib following investigator-assessed disease progression; these patients had a median progression-free survival from pazopanib initiation of 3·5 months (95% CI 2·2-5·2). 55 (72%) of the 76 pazopanib-treated patients had pazopanib-related grade 3 or worse adverse events, the most common of which was hypertension (15 [38%] in the pazopanib plus best supportive care group and 13 [36%] in the best supportive care group). 20 (26%) patients had pazopanib-related serious adverse events (14 [35%] in the pazopanib plus best supportive care group and six [17%] in the best supportive care group), including pulmonary embolism in eight (9%) patients (five [13%] in the pazopanib plus best supportive care group and three [7%] in the best supportive care group). Three pazopanib-related deaths occurred (two pulmonary embolisms [one in each group] and one hepatic cytolysis [in the best supportive care group]). Three adverse event-related but not pazopanib-related deaths occurred in the best supportive care group after switch to pazopanib; these deaths were from hyperammonaemic encephalopathy, pneumopathy, and respiratory failure. INTERPRETATION: Pazopanib plus best supportive care improves progression-free survival compared with best supportive care alone in patients with advanced GIST resistant to imatinib and sunitinib, with a toxicity profile similar to that reported for other sarcomas. This trial provides reference outcome data for future studies of targeted inhibitors in the third-line setting for these patients. FUNDING: GlaxoSmithKline, French National Cancer Institute, EuroSARC (FP7-278742), Centre Léon Bérard.