Sorafenib as third- or fourth-line treatment of advanced gastrointestinal stromal tumour and pretreatment including both imatinib and sunitinib, and nilotinib: A retrospective analysis

Emerging Targeted Therapeutic Strategies to Overcome Imatinib Resistance of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common malignant mesenchymal neoplasms of the gastrointestinal tract. The gold standard for the diagnosis of GISTs is morphologic analysis with an immunohistochemical evaluation plus genomic profiling to assess the mutational status of lesions. The majority of GISTs are driven by gain-of-function mutations in the proto-oncogene c-KIT encoding the tyrosine kinase receptor (TKR) known as KIT and in the platelet-derived growth factor-alpha receptor (PDGFRA) genes. Approved therapeutics are orally available as tyrosine kinase inhibitors (TKIs) targeting KIT and/or PDGFRA oncogenic activation. Among these, imatinib has changed the management of patients with unresectable or metastatic GISTs, improving their survival time and delaying disease progression. Nevertheless, the majority of patients with GISTs experience disease progression after 2-3 years of imatinib therapy due to the development of secondary KIT mutations. Today, based on the identification of new driving oncogenic mutations, targeted therapy and precision medicine are regarded as the new frontiers for GISTs. This article reviews the most important mutations in GISTs and highlights their importance in the current understanding and treatment options of GISTs, with an emphasis on the most recent clinical trials.

NCCN Guidelines® Insights: Gastrointestinal Stromal Tumors, Version 2.2022

Gastrointestinal stromal tumors (GIST) are the most common type of soft tissue sarcoma that occur throughout the gastrointestinal tract. Most of these tumors are caused by oncogenic activating mutations in the KIT or PDGFRA genes. The NCCN Guidelines for GIST provide recommendations for the diagnosis, evaluation, treatment, and follow-up of patients with these tumors. These NCCN Guidelines Insights summarize the panel discussion behind recent important updates to the guidelines, including revised systemic therapy options for unresectable, progressive, or metastatic GIST based on mutational status, and updated recommendations for the management of GIST that develop resistance to specific tyrosine kinase inhibitors.

Gastrointestinal Stromal Tumors: 10-Year Experience in Cancer Center-The Ottawa Hospital (TOH)

(1) Background: The management of gastrointestinal stromal tumors (GIST) has significantly evolved over the last two decades, with the introduction of tyrosine kinase inhibitors (TKI). We aim to report 10 years of experience of GIST management at a regional cancer center in Canada. (2) Methods: We retrospectively analyzed the records of 248 consecutive patients diagnosed with GIST between 2011 and 2021. We describe the clinical and pathological data, management, and outcome, including survival. (3) Results: The most common GIST sites were the stomach 63% (156), followed by the small bowel 29% (73). At diagnosis, 83% (206) of patients had localized disease (stage I-III). According to the modified National Institutes of Health consensus criteria (NIH) for GIST, around 45% (90) had intermediate or high-risk disease. Most patients, 86% (213), underwent curative surgical resection. Forty-nine patients received adjuvant imatinib, while forty-three patients had advanced disease and received at least one line of TKI. With a median follow-up of 47 months, the 5-year recurrence-free survival (RFS) rates for very low and low risk were 100% and 94%, respectively, while those for intermediate and high risk were 84% and 51%, respectively. The 5-year overall survival (OS) rates for very low and low risk were 100% and 94%, while intermediate, high risk, and advanced were 91%, 88%, and 65%, respectively. Using the Kaplan-Meier method, there were statistically significant differences in RFS and OS between NIH risk groups, p < 0.0005. In univariate analysis, ECOG, site, mitosis, secondary malignancy, and size were predictors for OS. High mitosis and large size (>5 cm) were associated with worse RFS. (4) Conclusions: Curative surgical resection remains the gold standard management of GIST. Our results are comparable to the reported literature. Further research is needed to explore histology's role in risk stratification and initiating adjuvant TKI.

An overview of agents and treatments for PDGFRA-mutated gastrointestinal stromal tumors

Platelet-derived growth factor receptor A (PDGFRA) mutations occur in approximately 10-15% of gastrointestinal stromal tumors (GISTs). These tumors with PDGFRA mutations have a different pathogenesis, clinical characteristics, and treatment response compared to tumors with receptor tyrosine kinase protein (KIT) mutations (60-70%). Many clinical studies have investigated the use of tyrosine kinase inhibitors mainly in patients with KIT mutations; however, there is a lack of attention to the PDGFRA-mutated molecular subtype. The main effective inhibitors of PDGFRA are ripretinib, avapritinib, and crenolanib, and their mechanisms and efficacy in GIST (as confirmed in clinical trials) are described in this review. Some multi-targeted tyrosine kinase inhibitors with inhibitory effects on this molecular subtype are also introduced and summarized in this paper. This review focuses on PDGFRA-mutated GISTs, introduces their clinical characteristics, downstream molecular signaling pathways, and existing resistance mechanisms. We focus on the most recent literature that describes the development of PDGFRA inhibitors and their use in clinical trials, as well as the potential benefits from different combination therapy strategies.

PHASE 2 STUDY OF PONATINIB IN ADVANCED GASTROINTESTINAL STROMAL TUMORS: EFFICACY, SAFETY, AND IMPACT OF LIQUID BIOPSY AND OTHER BIOMARKERS

PURPOSE

Evaluate ponatinib for advanced gastrointestinal stromal tumors (GIST).

PATIENTS AND METHODS

This single-arm phase 2 trial enrolled patients with metastatic and/or unresectable GIST with failure of prior tyrosine kinase inhibitor (TKI) treatment into two cohorts based on presence or absence of KIT exon 11 (ex11) primary mutations. Patients initially received ponatinib 45 mg once daily. Following a temporary clinical hold in October 2013, dose reductions were implemented to reduce risk of arterial occlusive events (AOEs). Primary endpoint was 16-week clinical benefit rate (CBR) in KIT ex11-positive cohort. KIT mutations in circulating tumor DNA (ctDNA) were assessed.

RESULTS

Forty-five patients enrolled (30 KIT ex11-positive and 15 KIT ex11-negative); median follow-up was 14.7 and 13.6 months, respectively, as of August 1, 2016. Sixteen-week CBR was 36% (KIT ex11-positive; primary endpoint) and 20% (KIT ex11-negative). ctDNA analyses (n = 37) demonstrated strong concordance of primary KIT mutations between plasma and tumor. At least two secondary mutations were detected in 35% of patients overall and 54% of KIT ex11-positive patients. Changes from baseline in mutated ctDNA levels were consistent with clinical activity. Ponatinib was ineffective in patients with KIT exon 9 primary mutations. Resistance was associated with emergence of V654A. AOEs and venous thromboembolic events occurred in three and two patients, respectively. Six patients died; two deaths (pneumonia and pulmonary embolism) were considered possibly ponatinib-related.

CONCLUSION

Ponatinib demonstrated activity in advanced GIST, particularly in KIT ex11-positive disease. ctDNA analysis confirmed heterogeneous resistance mutations in TKI-pretreated advanced GIST. Safety was consistent with previous studies.

Inhibition of PI3K and MAPK pathways along with KIT inhibitors as a strategy to overcome drug resistance in gastrointestinal stromal tumors

Activating mutations in KIT/PDGFRA receptor tyrosine kinases drive gastrointestinal stromal tumors (GIST). KIT/PDGFRA inhibitors, such as imatinib do not evoke an effective cytocidal response, leaving room for quiescence and development of multiple secondary resistance mutations. As the majority of the secondary resistance clones activate PI3K and MAPK pathways, we investigated whether combined targeting of KIT/PI3K/MAPK (KPM) pathways overcomes drug resistance and quiescence in GIST cells. We monitored the proliferation of imatinib-sensitive and-resistant GIST cell lines after treating them with various combinations of drugs to inhibit KPM pathways. Cytocidal response was evaluated through proliferation, apoptosis and colony outgrowth assays. Combined inhibition of KPM signaling pathways using a KPM inhibitor cocktail decreased the survival of drug-resistant GIST cells and dramatically reduced their proliferation. Downstream pathway analysis showed that the residual PI3K/MAPK signaling observed after KIT inhibitor treatment plays a role in mediating quiescence and drug resistance. The KPM inhibitor cocktail with sunitinib or regorafenib effectively induced apoptosis and prevented colony outgrowth after long-term drug removal, suggesting that it can be used as an effective strategy against quiescence and drug resistance in metastatic GIST.

Systemic therapy of advanced/metastatic gastrointestinal stromal tumors: an update on progress beyond imatinib, sunitinib, and regorafenib

Introduction: Discovery of oncogenic mutations in the KIT and PDGFRA tyrosine kinase receptor was a crucial step for the development of tyrosine kinase inhibitors (TKIs). Since then, GIST became a model for the development of molecular-targeted therapy, which led to dramatically improved median overall survival of advanced GIST. Still, further progress is needed after third-line or for TKI resistant mutations. Areas covered: In this review, after a brief introduction on imatinib, sunitinib, and regorafenib, an overview of TKIs that was evaluated beyond these drugs is provided, with a main focus on the novel approved TKIs. Expert opinion: Combination therapies have thus far not fulfilled their promise in GIST, nor did immunotherapy. Increased understanding of GIST and advances in the development of molecular-targeted drugs led to the introduction of ripretinib and avapritinib. Furthermore, NTRK inhibitors became available for ultrarare NTRK fusions. Solutions for NF1 and BRAF mutated and SDH-deficient GIST are still to be awaited. This all underlines the need for adequate molecular profiling of high-risk GISTs before treatment is started. Possibly by using circulating tumor DNA in the future, targeting resistance mutations with specific drugs along the course of the disease would be easier, avoiding multiple tumor biopsies.

Imatinib in combination with phosphoinositol kinase inhibitor buparlisib in patients with gastrointestinal stromal tumour who failed prior therapy with imatinib and sunitinib: a Phase 1b, multicentre study

Background

The majority of patients with advanced gastrointestinal stromal tumours (GISTs) develop resistance to imatinib and sunitinib, the standard of care for these patients. This study evaluated the combination of buparlisib, an oral phosphoinositide 3-kinase (PI3K) inhibitor, with imatinib in patients with advanced GIST, who have failed prior therapy with imatinib and sunitinib.

Methods

This Phase 1b, multicentre, open-label study aimed to determine the maximum tolerated dose (MTD) and/or a recommended Phase 2 dose of buparlisib in combination with 400 mg of imatinib through a dose-escalation part and a dose-expansion part, and also evaluated the clinical profile of the combination.

Results

Sixty patients were enrolled, including 25 in the dose-escalation part and 35 in the dose-expansion part. In the combination, MTD of buparlisib was established as 80 mg. No partial or complete responses were observed. The estimated median progression-free survival was 3.5 months in the expansion phase. Overall, 98.3% of patients had treatment-related adverse events (AEs), including 45% with grade 3 or 4 AEs.

Conclusions

Buparlisib in combination with imatinib provided no additional benefit compared with currently available therapies. Due to the lack of objective responses, further development of this combination was not pursued for third-line/fourth-line advanced/metastatic GIST.

Trial registration number

NCT01468688.

Real-World Evidence of Patient Outcome Following Treatment of Advanced Gastrointestinal Stromal Tumor (GIST) with Imatinib, Sunitinib, and Sorafenib in Publicly Funded Health Care in Poland

Background

This study aimed to undertake an analysis of ten years of real-world evidence (RWE) on overall survival (OS) following treatment of advanced gastrointestinal stromal tumor (GIST) with imatinib, sunitinib, and sorafenib using data from the Polish National Health Fund.

Material/Methods

Data from the Polish National Health Fund, the sole Polish public payer, identified 1,641 patients with advanced GIST who were treated with imatinib (n=1047), sunitinib (n=457), and sorafenib (n=137). The differences in overall survival (OS) were analyzed.

Results

For patients with advanced GIST, the median follow-up time for patients treated with imatinib was 71 months (95% CI, 64.8–79.2), the median OS was 56.9 months (95% CI, 50.4–61.2), with survival at 12 months (89.5%), 24 months (77.9%), 36 months (66.9%), and 60 months (48.4%). The median follow-up time for patients treated with sunitinib was 41.4 months (95% CI, 34.6–49.3), the median OS was 22.8 months (95% CI, 19.2–26.8), with survival at 12 months (68.2%), 24 months (47.1%), and 36 months (31%). The median follow-up time for patients treated with sorafenib was 17.4 months (95% CI, 14.6–22.9), the median OS was 16.9 months (95% CI, 13.7–24.3), with survival at 12 months (61.9%), at 24 months (36.2%), and at 36 months (16.8%).

Conclusions

Real-world data collected in a ten-year period confirmed the effectiveness of the use of imatinib, sunitinib, or sorafenib for the treatment of advanced GIST and was comparable with the findings from clinical trials.

New frontiers in the medical management of gastrointestinal stromal tumours

The tyrosine kinase inhibitor (TKI) imatinib has radically changed the natural history of KIT-driven gastrointestinal stromal tumours (GISTs). Approved second-line and third-line medical therapies are represented by the TKIs sunitinib and regorafenib, respectively. While imatinib remains the cardinal drug for patients with GISTs, novel therapies are being developed and clinically tested to overcome the mechanisms of resistance after treatments with the approved TKI, or to treat subsets of GISTs driven by rarer molecular events. Here, we review the therapy of GISTs, with a particular focus on the newest drugs in advanced phases of clinical testing that might soon change the current therapeutic algorithm.

Survival in advanced GIST has improved over time and correlates with increased access to post-imatinib tyrosine kinase inhibitors: results from Life Raft Group Registry

Background

The use of imatinib, sunitinib, and regorafenib has transformed the treatment of advanced GIST. Sunitinib and regorafenib improve progression free-survival in the second (2L) and third (3L) line, respectively, compared with placebo. However, the impact of these agents on overall survival (OS) is unclear.

Methods

The Life Raft Group (LRG) patient registry contains records from 1716 GIST patients; 526 have advanced to at least 2L treatment. Patient-reported treatment and outcome data were examined to determine treatment patterns and their impact on OS.

Results

Median OS from start of 2L therapy was 32.4 months for sunitinib (n = 436) compared with 27.1 months for patients treated with any other 2L drug (n = 74, p = 0.023, HR 1.377) and 16.8 months for patients who never received sunitinib in any treatment line (n = 42, p = 0.028, HR 1.52). In patients reporting progression in 2L, the median OS in patients subsequently receiving 3L regorafenib (n = 53, 26.2 months) was longer than that of 3L patients who never received regorafenib in any line of therapy (n = 174, 14.3 months, p = 0.0002, HR 2.231), and was longer than that of patients who received any other 3L treatment (19.8 months, p = 0.044, HR 1.525). OS for advanced GIST patients in the LRG registry has improved over time (p = 0.0013), correlated with the increased use of TKIs in ≥ 2L settings.

Conclusions

In our analysis, sunitinib and regorafenib significantly improved OS compared with patients who never received these agents. Our data also support the hypothesis that the use of KIT/PDGFRA inhibitors, including non-approved agents, has improved OS for patients with imatinib- and sunitinib-resistant GIST.

Electronic supplementary material

The online version of this article (10.1186/s13569-019-0114-5) contains supplementary material, which is available to authorized users.

Gastrointestinal Stromal Tumor (GIST) from esophagus to anorectum - diagnosis, response evaluation and surveillance on computed tomography (CT) scan

Gastrointestinal stromal tumor (GIST) are the most common non epithelial tumor of the gastrointestinal (GI) tract. They arise from interstitial cells of Cajal present in the myenteric plexus. They can also arise outside the GI tract from mesentery, retro peritoneum and omentum. With the advent of new targeted molecular therapy c- tyrosine kinase inhibitor (Imatinib), it has become important to differentiate between response and pseudo-progression of the disease as response evaluation criteria for GIST are different from Response Evaluation Criteria in Solid Tumors (RECIST). Purpose of this pictorial essay is to enumerate the characteristic CT features of GIST, and discuss atypical features and response evaluation criteria.

Making progress in a rare disease: emerging therapeutics in soft tissue sarcomas

Sarcomas are rare tumors derived from mesenchymal connective tissues in the body. Because there are well over 50 histologic sarcoma subtypes, including malignant and non-malignant pathologies, clinical courses and therapeutic management are widely divergent. In general, therapeutic options across all soft tissue sarcomas are limited in number and are often generalized across multiple sarcoma histologies. The recent emergence of molecularly targeted therapies and immune-based agents presents a future of refined systemic treatment practices that are rationally tailored to the tumor by histologic subtype and biologic mechanisms.

The analysis of the long-term outcomes of sorafenib therapy in routine practice in imatinib and sunitinib resistant gastrointestinal stromal tumors (GIST)

Aim of the study

was to analyze the outcome of treatment and factors predicting results of sorafenib therapy in inoperable/metastatic CD117-positive GIST patients after failure on imatinib and sunitinib.

Material and methods

We identified 60 consecutive patients (40 men, 20 women) with advanced inoperable/metastatic GIST after failure on at least imatinib and sunitinib treated in one sarcoma center with sorafenib at initial dose 2 × 400 mg daily in 2007-2015 (in 56 cases it was 3^rd line therapy). Median follow-up time was 39 months.

Results

One year progression-free survival (PFS; calculated from the date of the start of sorafenib to disease progression) rate was 23% and median PFS = 7.7 months. The median overall survival (OS) was 13.5 months calculated from sorafenib start (1-year OS rate = 57%) and 7 years from imatinib start. Three patients (5%) had objective partial responses to therapy, 31 patients (52%) had stabilization of disease > 4 months. Primary tumor mutational status was known in 43 cases (73%), but we have not identified the differences in PFS between tumors carrying different KIT/PDGFRA mutations. The most common adverse events were: diarrhoea, hand and foot syndrome, fatigue, loss of weight and skin reactions; grade 3-5 toxicity occurred in 35% of patients. 23 patients required sorafenib dose reductions due to AEs.

Conclusions

We confirmed that many advanced GIST patients benefit from sorafenib therapy after imatinib/sunitinib failure with OS > 1 year.

Dovitinib in patients with gastrointestinal stromal tumour refractory and/or intolerant to imatinib

Background:

This multicentre phase II trial (DOVIGIST) evaluated the antitumour activity of dovitinib as second-line treatment of patients with gastrointestinal stromal tumour (GIST) refractory to imatinib or who do not tolerate imatinib.

Methods:

Patients received oral dovitinib 500 mg day⁻¹, 5 days on/2 days off, until GIST progression or unacceptable toxicity, with an objective to evaluate efficacy, assessed as the disease control rate (DCR) at 12 weeks. Tumour assessment and response to dovitinib therapy were evaluated by Response Evaluation Criteria In Solid Tumours (RECIST v1.1) and the Choi criteria. Secondary objectives included assessment of progression-free survival (PFS), safety and tolerability, and DCR at the end of treatment.

Results:

Thirty-eight of the 39 patients enrolled had histologically confirmed GIST. The DCR at 12 weeks was 52.6% (90% confidence interval (CI), 38.2–66.7%) meeting the preset efficacy criterion for the primary end point. The objective response rate (complete response+partial response) was 2.6% (1 of 38; 90% CI, 0.1–11.9%), and 5.3% (n=2; 90% CI, 0.9–15.7%) at the end of the study. The median PFS was 4.6 months (90% CI, 2.8–7.4 months). Dose interruption was required in 26 patients (66.7%), of which 18 (69.2%) were due to adverse events. The most frequently observed grade 3 adverse events included hypertension (n=7), fatigue (n=5), vomiting (n=4), hypertriglyceridaemia (n=4), and γ-glutamyltransferase increase (n=4).

Conclusions:

Dovitinib is an active treatment for patients with GIST who are intolerant to imatinib or whose GIST progresses on imatinib.

Long-term follow-up results of the multicenter phase II trial of regorafenib in patients with metastatic and/or unresectable GI stromal tumor after failure of standard tyrosine kinase inhibitor therapy

BACKGROUND

This investigator-initiated trial provided the justification for the phase III GRID study resulting in worldwide regulatory approval of regorafenib as a third-line therapy for patients with metastatic gastrointestinal stromal tumors (GIST). We report the genotype analyses, long-term safety, and activity results from this initial trial of regorafenib in GIST.

PATIENTS AND METHODS

The trial was conducted between February 2010 and January 2014, among adult patients with metastatic GIST, after failure of at least imatinib and sunitinib. Patients received regorafenib orally, 160 mg once daily, days 1-21 of a 28-day cycle. Clinical benefit rate (CBR), defined as complete or partial response (PR), or stable disease lasting ≥16 weeks per RECIST 1.1, progression-free survival (PFS), overall survival (OS), long-term safety data, and metabolic response by functional imaging were assessed.

RESULTS

Thirty-three patients received at least one dose of regorafenib. The median follow-up was 41 months. CBR was documented in 25 of 33 patients [76%; 95% confidence interval (CI) 58% to 89%], including six PRs. The median PFS was 13.2 months (95% CI 9.2-18.3 months) including four patients who remained progression-free at study closure, each achieving clinical benefit for more than 3 years (range 36.8-43.5 months). The median OS was 25 months (95% CI 13.2-39.1 months). Patients whose tumors harbored a KIT exon 11 mutation demonstrated the longest median PFS (13.4 months), whereas patients with KIT/PDGFRA wild-type, non-SDH-deficient tumors experienced a median 1.6 months PFS (P < 0.0001). Long-term safety profile is consistent with previous reports; hand-foot skin reaction and hypertension were the most common reasons for dose reduction. Notably, regorafenib induced objective responses and durable benefit in SDH-deficient GIST.

CONCLUSIONS

Long-term follow-up of patients with metastatic GIST treated with regorafenib suggests particular benefit among patients with primary KIT exon 11 mutations and those with SDH-deficient GIST. Dose modifications are frequently required to manage treatment-related toxicities.

CLINICAL TRIAL NUMBER

NCT01068769.

An Unusual Case of Central Retinal Vein Occlusion and Review of the Toxicity Profile of Regorafenib in GIST Patients

Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the gastrointestinal tract with around 5000 new cases per year. Outcomes for patients with GIST dramatically improved after the development of tyrosine kinase inhibitors targeted against the aberrant signaling pathways that drive GIST oncogenesis. Majority of patients derive benefit from first-line imatinib, and the type of driver mutation is predictive of response. However, almost half of the patients eventually develop resistance to initial targeted therapy and further lines of treatment do not have the same impact. Regorafenib is an oral multi-kinase inhibitor approved as a third-line therapy for advanced GIST and though its efficacy is limited in comparison to imatinib, it has activity across the various driver mutation categories in GIST even in the setting of imatinib resistance. Herein, we describe a case of central retinal vein occlusion (CRVO) secondary to regorafenib and review regorafenib's efficacy and toxicity profile.

Update on clinical research and state of the art management of patients with advanced sarcomas and GIST

Sarcomas constitute a rare group of malignancies. According to histology, different treatment options are effective. For gastrointestinal stromal tumours (GISTs), targeted treatment with imatinib controls about 20% of advanced or metastatic disease, whereas chemotherapy is more effective for the rest of the sarcomas. Currently, new targeted treatments are emerging, showing activity in cases resistant to established primary treatment. On the other hand, the exciting results of immunotherapy for other solid tumours, for example, melanoma and lung cancer, make it a promising option in the fight against sarcomas. In this review, we have collected data of established and promising treatments in trials with a view to facilitating the sequencing of sarcoma treatments and for identifying the future of these therapeutic options.

Sorafenib: 10 years after the first pivotal trial

Sorafenib is an oral multikinase inhibitor with anticancer activity against a wide spectrum of cancers. It is currently approved for the treatment of patients with hepatocellular carcinoma, advanced renal cell carcinoma or progressive, locally advanced or metastatic differentiated thyroid carcinoma. In this review, we present a number of studies that investigated the efficacy and safety of sorafenib in these settings. We also discuss the perspectives on the use of this molecule, including the role of sorafenib as comparator for the development of new drugs, the combination of sorafenib with additional therapies (such as transarterial chemoembolization for hepatocellular carcinoma) and the use of this treatment in several other advanced refractory solid tumors.

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.

Contemporary Management of Metastatic Gastrointestinal Stromal Tumors: Systemic and Locoregional Approaches

The treatment of metastatic gastrointestinal stromal tumors (GISTs) changed dramatically with the introduction of imatinib into the therapeutic lexicon in 2001. Over the past 15 years, tyrosine kinase inhibitors in the adjuvant and metastatic settings have remained the standard of care for this disease, though alternate classes of agents and new therapeutic targets are being actively explored in clinical trials. Although data are limited, the use of surgical and non-surgical locoregional techniques for the treatment of GIST metastases has increased and given reports of promising and durable responses. Herein we provide an overview of the contemporary therapeutic landscape of metastatic GIST.

Clinical Perspectives on Targeting Therapies for Personalized Medicine

Expected benefits from new technology include more efficient patient selection for clinical trials, more cost-effective treatment pathways for patients and health services and a more profitable accelerated approach for drug developers. Regulatory authorities expect the pharmaceutical and biotechnology industries to accelerate their development of companion diagnostics and companion therapeutics toward the goal of safer and more effective personalized medicine, and expect health services to fund and prescribers to adopt these new therapeutic technologies.

This review discusses the importance of a range of new approaches to developing new and reprofiled medicines to treat common and serious diseases, and rare diseases: new network pharmacology approaches, adaptive trial designs with enriched populations more likely to respond safely to treatment, as assessed by companion diagnostics for response and toxicity risk and use of “real world” data.

Case studies are described of single and multiple protein drug targets in several important therapeutic areas. These case studies also illustrate the value and complexity of use of selective biomarkers of clinical response and risk of adverse drug effects, either singly or in combination.

Emerging Agents for the Treatment of Advanced, Imatinib-Resistant Gastrointestinal Stromal Tumors: Current Status and Future Directions

Imatinib is strongly positioned as the recommended first-line agent for most patients with advanced gastrointestinal stromal tumor (GIST) due to its good efficacy and tolerability. Imatinib-resistant advanced GIST continues to pose a therapeutic challenge, likely due to the frequent presence of multiple mutations that confer drug resistance. Sunitinib and regorafenib are approved as second- and third-line agents, respectively, for patients whose GIST does not respond to imatinib or who do not tolerate imatinib, and their use is supported by large randomized trials. ATP-mimetic tyrosine kinase inhibitors provide clinical benefit even in heavily pretreated GIST suggesting that oncogenic dependency on KIT frequently persists. Several potentially useful tyrosine kinase inhibitors with distinct inhibitory profiles against both KIT ATP-binding domain and activation loop mutations have not yet been fully evaluated. Agents that have been found promising in preclinical models and early clinical trials include small molecule KIT and PDGFRA mutation-specific inhibitors, heat shock protein inhibitors, histone deacetylase inhibitors, allosteric KIT inhibitors, KIT and PDGFRA signaling pathway inhibitors, and immunological approaches including antibody-drug conjugates. Concomitant or sequential administration of tyrosine kinase inhibitors with KIT signaling pathway inhibitors require further evaluation, as well as rotation of tyrosine kinase inhibitors as a means to suppress drug-resistant cell clones.

Beyond standard therapy: drugs under investigation for the treatment of gastrointestinal stromal tumor

INTRODUCTION

Gastrointestinal stromal tumor (GIST) is the most common nonepithelial malignancy of the GI tract. With the discovery of KIT and later platelet-derived growth factor α (PDGFRA) gain-of-function mutations as factors in the pathogenesis of the disease, GIST was the quintessential model for targeted therapy. Despite the successful clinical use of imatinib mesylate, a selective receptor tyrosine kinase (RTK) inhibitor that targets KIT, PDGFRA and BCR-ABL, we still do not have treatment for the long-term control of advanced GIST.

AREAS COVERED

This review summarizes the drugs that are under investigation or have been assessed in trials for GIST treatment. The article focuses on their mechanisms of actions, the preclinical evidence of efficacy, and the clinical trials concerning safety and efficacy in humans.

EXPERT OPINION

It is known that KIT and PDGFRA mutations in GIST patients influence the response to treatment. This observation should be taken into consideration when investigating new drugs. RECIST was developed to help uniformly report efficacy trials in oncology. Despite the usefulness of this system, many questions are being addressed about its validity in evaluating the true efficacy of drugs knowing that new targeted therapies do not affect the tumor size as much as they halt progression and prolong survival.

Systemic therapy options for advanced gastrointestinal stromal tumors beyond first-line imatinib: a systematic review

ABSTRACT 

This systematic review aims at assessment of the available evidence for systemic therapy options for patients with advanced gastrointestinal stromal tumors beyond first-line imatinib. Eligible trials were identified using databases search. In total, 26 studies were eligible and included in the final analysis. Among second-line studies, median progression-free survival ranged from 1.9 to 10 months while median overall survival ranged from 15 to 62 months. Among third-line agents, median progression-free survival ranged from 1.8 to 4.6 months while median overall survival ranged from 8.2 to 19 months. The available data for the second-line suggest that sunitinib is the best option while in the third line, regorafenib is the best option.

Regorafenib in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the GI tract and constitute less than 1% of all digestive tract tumors--the stomach is the most common site. Regorafenib is a multi-tyrosine kinase inhibitor with regulatory approvals granted for colorectal cancers and GIST. The US FDA granted approval for the use of regorafenib in February 2013 in patients with advanced GIST for those who had failed on imatinib and sunitinib. This was based on a pivotal Phase III double-blind placebo controlled randomized trial that showed that there was a significant improvement in progression-free survival for patients on regorafenib.

Therapeutic targets in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common type of mesenchymal tumor of the gastrointestinal tract. The tumorigenesis of GISTs is driven by gain-of-function mutations in KIT or platelet-derived growth factor receptor α (PDGFRA), resulting in constitutive activation of the tyrosine kinase and its downstream signaling pathways. Oncogenic KIT or PDGFRA mutations are compelling therapeutic targets for the treatment of GISTs, and the KIT/PDGFRA inhibitor imatinib is the standard of care for patients with metastatic GISTs. However, most GIST patients develop clinical resistance to imatinib and other tyrosine kinase inhibitors. Five mechanisms of resistance have been characterized: (1) acquisition of a secondary point mutation in KIT or PDGFRA; (2) genomic amplification of KIT; (3) activation of an alternative receptor tyrosine kinase; (4) loss of KIT oncoprotein expression; and (5) wild-type GIST. Currently, sunitinib is used as a second-line treatment for patients after imatinib failure, and regorafenib has been approved for patients whose disease is progressing on both imatinib and sunitinib. Phase II/III trials are currently in progress to evaluate novel inhibitors and immunotherapies targeting KIT, its downstream effectors such as phosphatidylinositol 3-kinase, protein kinase B and mammalian target of rapamycin, heat shock protein 90, and histone deacetylase inhibitor. Other candidate targets have been identified, including ETV1, AXL, insulin-like growth factor 1 receptor, KRAS, FAS receptor, protein kinase c theta, ANO1 (DOG1), CDC37, and aurora kinase A. These candidates warrant clinical evaluation as novel therapeutic targets in GIST.

A Decade of Research on the Quality of Systemic Cancer Therapy in Routine Care: What Aspects of Quality Are We Measuring?

Most studies evaluating quality of systemic cancer therapy have focused on access to cytotoxic chemotherapy in early-stage disease. Studies on other aspects of quality and in different clinical settings are needed.

Meta-analysis for the association between overall survival and progression-free survival in gastrointestinal stromal tumor

PURPOSE

Gastrointestinal stromal tumor (GIST) is a relatively rare tumor that is treated with targeted therapies in advanced stages. Randomized clinical trials (RCT) often require long follow-up and large sample sizes to evaluate overall survival (OS), the gold-standard measure of treatment efficacy. However, changes in therapy following disease progression may complicate survival assessments. Establishing surrogate endpoints may facilitate the drug approval and availability of new efficacious treatments; however, no published studies have investigated this topic in unresectable and/or metastatic GIST.

EXPERIMENTAL DESIGN

A systematic literature review identified 14 RCTs and five observational studies of sufficient methodologic quality published between January 1995 and December 2013 (29 treatment arms; 2,189 patients). Weighted linear regression was used to evaluate the relation between median OS and median progression-free survival (PFS) for all arms combined and stratified by treatment line, treatment type, and quality score.

RESULTS

Median OS and PFS were positively related with a correlation of 0.91. The association was still moderate (correlation 0.72) after eliminating four influential data points. In stratified analyses, correlation of OS and PFS was greater in later lines of therapy (first line = 0.52; second line = 0.80; third- and later-line = 0.70) and imatinib showed a stronger association (0.91) than other evaluated treatments (-0.26 to 0.69).

CONCLUSION

This analysis identified a strong relationship between median OS and PFS, especially in later lines of therapy. Findings suggest that PFS could serve as a surrogate marker for OS; however, analyses of patient-level data are needed to establish its validity in GIST.

Antitumor effect of the tyrosine kinase inhibitor nilotinib on gastrointestinal stromal tumor (GIST) and imatinib-resistant GIST cells

Despite the benefits of imatinib for treating gastrointestinal stromal tumors (GIST), the prognosis for high risk GIST and imatinib-resistant (IR) GIST remains poor. The mechanisms of imatinib resistance have not yet been fully clarified. The aim of the study was to establish imatinib-resistant cell lines and investigate nilotinib, a second generation tyrosine kinase inhibitor (TKI), in preclinical models of GIST and imatinib-resistant GIST. For a model of imatinib-resistant GIST, we generated resistant cells from GK1C and GK3C cell lines by exposing them to imatinib for 6 months. The parent cell lines GK1C and GK3C showed imatinib sensitivity with IC₅₀ of 4.59±0.97 µM and 11.15±1.48 µM, respectively. The imatinib-resistant cell lines GK1C-IR and GK3C-IR showed imatinib resistance with IC₅₀ values of 11.74±0.17 µM (P<0.001) and 41.37±1.07 µM (P<0.001), respectively. The phosphorylation status of key cell signaling pathways, receptor tyrosine kinase KIT (CD117), platelet-derived growth factor receptor alpha (PDGFRA) and downstream signaling kinases: serine-threonine kinase Akt (AKT) and extracellular signal-regulated kinase 1/2 (ERK1/2) or the non-receptor tyrosine kinase: proto-oncogene tyrosine-protein kinase Src (SRC), was analyzed in established cell lines and ERK1/2 phosphorylation was found to be increased compared to the parental cells. Nilotinib demonstrated significant antitumor efficacy against GIST xenograft lines and imatinib-resistant GIST cell lines. Thus, nilotinib may have clinical potential for patients with GIST or imatinib-resistant GIST.

Durable response with a combination of imatinib and sorafenib in KIT exon 17 mutant gastrointestinal stromal tumor

Imatinib, a selective KIT tyrosine-kinase inhibitor is considered standard first line therapy in metastatic gastrointestinal stromal tumors (GISTs). However, up to 40-50% of patients develop resistance to imatinib resulting in progression of disease. Other kinase inhibitors such as sunitinib, and most recently regorafenib have been approved as second and third line options respectively. Sorafenib has also been used following progression on standard therapies. Here we present the case of a patient with stage IV GIST of the rectum who had a rare exon 17 mutation treated prior to the approval of regorafenib. Therapy initially consisted of single agent imatinib, followed by sunitinib then sorafenib. Following continued progression of disease, the patient went on to develop stable disease for close to two years on a combination of sorafenib and imatinib.

Sorafenib-Induced Grade Four Hepatotoxicity in a Patient with Recurrent Gastrointestinal Stromal Tumor (GIST): A Case Report and Review of Literature

Gastrointestinal stromal tumor is a rare mesenchymal tumor. Sorafenib is an effective medication in these tumors based on two phase II clinical trials and a retrospective analysis. We report a rare case of a 57-year-old male with acute hepatotoxicity from sorafenib. He was treated conservatively with IV fluids and prednisolone. Liver function tests improved over 2 months. We conclude that sorafenib could cause life-threatening hepatotoxicity and patients taking sorafenib need to be closely monitored.

What are the current outcomes of advanced gastrointestinal stromal tumors: who are the long-term survivors treated initially with imatinib?

The introduction of imatinib to clinical practice revolutionized therapy of advanced gastrointestinal stromal tumors (GIST), but its long-term results have been only just collected. We have attempted to identify factors related to the long-term survival. We have analyzed the data of 430 inoperable/metastatic/recurrent GIST patients treated with imatinib in reference centers, assessed the factors influencing the long-term overall survival (OS), and compared the outcomes in three periods of initiation of imatinib therapy during one decade (2001–2003, 2004–2006, 2007–2010). During analyzed time periods, we have found decrease in median largest tumor size at the start of imatinib therapy: 90.5 mm (2001–2003) versus 74 mm (2004–2006) versus 58 mm (2007–2010) (p = 0.002). Median progression-free survival (PFS) on 1st line imatinib was 37.5 months, without differences in PFS between three groups. Median OS was 5.8 years, 8-year OS rate was 43 %, and no difference in OS was demonstrated for patients treated in analyzed time periods. Independent good prognostic factors for longer OS were as follows: surgery of residual disease, initial WHO performance status 0/1, normal baseline albumin level, and the presence of exon 11 KIT mutations. Current median OS in advanced GIST reaches 6 years. The long-term survivors were characterized by smaller maximal tumors at imatinib start, better blood tests results, better performance status, and the surgical removal of residual disease. The latter might reduce the impact of tumor size and equalize the long-term results of therapy during last decade from introduction of imatinib. After introduction of subsequent lines of therapy (as sunitinib), the effect of primary mutational status on the long-term OS is also less visible.

Pharmacokinetics, clinical indications, and resistance mechanisms in molecular targeted therapies in cancer

The strategy for discovery and development of new cancer drugs has shifted the field from cytotoxic agents to therapies that selectively target oncogenic drivers. In the last decade, a number of targeted cancer therapies have been discovered and proven effective in a variety of hematological and solid malignancies. In this article, we review clinical pharmacokinetic characteristics of the U.S. Food and Drug Administration-approved targeted therapies and provide an overview of key clinical trials that led to approval of these drugs. The major limiting factor of targeted treatment is the development of resistance. We describe general principles of resistance and specific, clinically confirmed mechanisms of resistance to several therapies in different malignancies.

Phase II study of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours after failure of imatinib and sunitinib

Background:

This prospective, phase II trial evaluated the efficacy and safety of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours (GISTs) after failure of at least imatinib and sunitinib.

Methods:

Patients received oral dovitinib, 500 mg once daily, for 5 consecutive days, followed by a 2-day rest, every 28 days. The primary endpoint was disease control rate (DCR; objective response+stable disease (SD)) at 24 weeks, assessed by computed tomography (CT) scan according to RECIST v1.0. Metabolic response was evaluated by positron emission tomography (PET)–CT scans performed at baseline and after 4 weeks of treatment.

Results:

Between September 2011 and April 2012, 30 patients were enroled. DCR at 24 weeks by RECIST v1.0 was 13% and one patient (3%) had a partial response. Based on the European Organization for Research and Treatment of Cancer PET response criteria, four patients (13%) had a metabolic partial response after 4 weeks of treatment. At a median follow-up of 8.3 months (range, 6.3–12.2 months), median progression-free survival (PFS) was 3.6 months (95% confidence interval (CI), 3.5–3.7 months) and median overall survival was 9.7 months (95% CI, 6.0–13.4 months). Metabolic progressive disease at Week 4 was significantly associated with shorter PFS (P=0.03). Grade 3/4 adverse events included asthenia (20%), neutropenia (13%), thrombocytopenia (10%), and hypertriglyceridaemia (10%). Most toxicities were manageable by dose modification.

Conclusion:

Dovitinib showed modest antitumour activity with manageable toxicities in heavily pretreated patients with advanced GISTs.