New frontiers in the medical management of gastrointestinal stromal tumours

Radiofrequency ablation vs. hepatectomy for liver metastases from gastrointestinal stromal tumors

For patients with gastrointestinal stromal tumors (GISTs) and liver metastases, there is still debate about whether radiofrequency ablation (RFA) or hepatectomy is preferable. The present study aimed to compare the clinical outcomes of RFA with hepatectomy in patients with GISTs and liver metastases. The present retrospective study consisted of a cohort of 43 patients who had been diagnosed with liver metastases from GISTs between January 2010 and December 2022. The study included 18 patients who received RFA combined with tyrosine kinase inhibitor (TKI) therapy (RFA group) and 25 patients who underwent hepatectomy combined with TKI therapy (hepatectomy group). For the patients with liver metastases, the progression-free survival (PFS) rates at 1, 3 and 5 years were 66.5, 38.2 and 33.9%, respectively. Notably, patients in the hepatectomy group exhibited significantly improved PFS times compared with those in the RFA group (median PFS, 42.7 months vs. 14.3 months; P=0.034). Furthermore, the time to imatinib treatment failure (TTF) was notably improved in the hepatectomy group compared with that in the RFA group, and this difference was statistically significant (median TTF, 71.1 vs. 38.0 months; P=0.041). However, the overall survival (OS) times of patients who received RFA and those who had hepatectomy did not differ significantly (median OS, not reached vs. not reached, P=0.120). There was no statistically significant distinction in PFS and TTF between patients who underwent hepatectomy combined with postoperative TKI and those who underwent hepatectomy combined with perioperative TKI (median PFS, 29.5 vs. not reached; P=0.520; median TTF, 66.4 months vs. 71.1 months; P=0.430). The univariate and multivariate analyses consistently identified the sole prognostic factor affecting PFS as hepatectomy combined with TKI therapy (hazard ratio, 0.379; 95% CI, 0.159-0.899; P=0.028). In conclusion, hepatectomy combined with TKI therapy improved prognosis for patients with liver metastases to a greater extent than RFA combined with TKI therapy. For this type of patient, hepatectomy may be a preferable option.

FDA-approved heterocyclic molecules for cancer treatment: Synthesis, dosage, mechanism of action and their adverse effect

As the incorporation of heterocycles increases the physical characteristics and biological activity of pharmacological molecules, heterocyclic scaffolds are commonly discovered as common cores in a wide spectrum of biologically active drugs. In the contemporary context, many heterocycles have arisen, playing vital roles in diverse pharmaceutical compounds that benefit humanity. Over 85 % of FDA-approved medication molecules contain heterocycles, and most importantly, numerous heterocyclic medicinal molecules indicate potential benefits against a range: of malignancies. The unique flexibility and dynamic core scaffold of these compounds have aided anticancer research. These medications are used to treat cancer patients by targeting particular genes, enzymes, and receptors. Aside from the drugs that are now on the market, numerous forms are being researched for their potential anti-cancer activity. Here in this review, we classified some molecules and biologically active heterocycles containing anticancer medicinal moieties approved by the FDA between 2019 and 2021 based on their use in various forms of cancer. We will focus on those that are suitable for cancer treatment, as well as the essential biochemical mechanisms of action, biological targets, synthetic methods, and inherent limiting considerations in their use.

Overcoming the imatinib-resistant BCR-ABL mutants with new ureidobenzothiazole chemotypes endowed with potent and broad-spectrum anticancer activity

The design of kinase inhibitors targeting the oncogenic kinase BCR-ABL constitutes a promising paradigm for treating chronic myeloid leukaemia (CML). Nevertheless, the efficacy of imatinib, the first FDA-approved targeted therapy for CML, is curbed by the emergence of resistance. Herein, we report the identification of the 2-methoxyphenyl ureidobenzothiazole AK-HW-90 (2b) as a potent pan-BCR-ABL inhibitor against imatinib-resistant mutants, particularly T315I. A concise array of six compounds 2a-f was designed based on our previously reported benzothiazole lead AKE-5l to improve its BCR-ABL^T315I inhibitory activity. Replacing the 6-oxypicolinamide moiety of AKE-5l with o-methoxyphenyl and changing the propyl spacer with phenyl afforded 2a and AK-HW-90 (2b) with IC₅₀ values of 2.0 and 0.65 nM against BCR-ABL^T315I, respectively. AK-HW-90 showed superior anticancer potency to imatinib against multiple cancer cells (NCI), including leukaemia K-562. The obtained outcomes offer AK-HW-90 as a promising candidate for the treatment of CML and other types of cancer.

Chemistry and Pharmacology of Fluorinated Drugs Approved by the FDA (2016-2022)

Fluorine is characterized by high electronegativity and small atomic size, which provide this molecule with the unique property of augmenting the potency, selectivity, metabolic stability, and pharmacokinetics of drugs. Fluorine (F) substitution has been extensively explored in drug research as a means of improving biological activity and enhancing chemical or metabolic stability. Selective F substitution onto a therapeutic or diagnostic drug candidate can enhance several pharmacokinetic and physicochemical properties such as metabolic stability and membrane permeation. The increased binding ability of fluorinated drug target proteins has also been reported in some cases. An emerging line of research on F substitution has been addressed by using 18F as a radiolabel tracer atom in the extremely sensitive methodology of positron emission tomography (PET) imaging. This review aims to report on the fluorinated drugs approved by the US Food and Drug Administration (FDA) from 2016 to 2022. It cites selected examples from a variety of therapeutic and diagnostic drugs. FDA-approved drugs in this period have a variety of heterocyclic cores, including pyrrole, pyrazole, imidazole, triazole, pyridine, pyridone, pyridazine, pyrazine, pyrimidine, triazine, purine, indole, benzimidazole, isoquinoline, and quinoline appended with either F-18 or F-19. Some fluorinated oligonucleotides were also authorized by the FDA between 2019 and 2022.

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.

Emerging Data on the Safety and Efficacy of Ripretinib for the Treatment of Gastrointestinal Stromal Tumors

In patients with gastrointestinal stromal tumors (GIST), systemic treatment after disease progression on imatinib is challenging. Sunitinib and regorafenib are approved in the second- and third-line setting, respectively, with activity against certain secondary mutations with comparatively much lower response rates and survival increment compared to imatinib. All three of these drugs were serendipitously found to have activity in GIST, starting with imatinib, which was formulated for its ability to inhibit BCR-ABL in chronic myelogenous leukemia. Ripretinib is a drug that was specifically developed as a more potent KIT tyrosine kinase inhibitor (TKI), with broad-spectrum activity against the mutations encountered in GIST. Encouraging responses in early and later lines of treatment in the Phase 1 trial of ripretinib in GIST led to the rapid development of this novel drug. In a Phase 3 randomized clinical trial with cross-over, ripretinib demonstrated superior PFS and overall survival (OS) in 4th-line treatment and beyond compared to placebo. This established 150 mg once daily ripretinib as the standard of care in this setting. Ripretinib is generally well tolerated, with common adverse effects of hair loss, diarrhea, cramps, fatigue and nausea. The favorable safety profile and efficacy of ripretinib prompted its evaluation in a randomized phase 3 trial in the 2nd-line treatment setting. However, it did not result in a longer PFS duration than sunitinib. Although the efficacy of ripretinib in this unselected patient population was not significantly different from that of sunitinib, the tolerability profile was better. This review article aims to review the efficacy and tolerability profile of ripretinib, together with its role in the setting of unresectable or metastatic GIST.

Efficacy and Safety of Avapritinib in Treating Unresectable or Metastatic Gastrointestinal Stromal Tumors: A Phase I/II, Open-Label, Multicenter Study

BACKGROUND

Avapritinib is a type 1 kinase inhibitor designed to potently and selectively inhibit oncogenic KIT/PDGFRA mutants by targeting the kinase active conformation. This multicenter, single-arm, open-label, phase I/II bridging study of NAVIGATOR in Chinese patients evaluated the safety and the antineoplastic activity of avapritinib in Chinese patients with unresectable/metastatic gastrointestinal stromal tumors (GIST).

METHODS

Phase I comprised dose escalation for safety and phase II dose determination. Phase II comprised dose expansion for safety/efficacy evaluations in patients with PDGFRA D842V mutations or patients having received at least 3 lines of therapy without PDGFRA D842V mutations. The primary endpoints were recommended phase II dose, safety, and Independent Radiology Review Committee (IRRC)-assessed objective response rate (ORR).

RESULTS

No dose-limiting toxicities occurred (n = 10); the recommended phase II dose was avapritinib 300 mg once daily orally. Fifty-nine patients initially received avapritinib 300 mg. Common grade ≥3 treatment-related adverse events were anemia, decreased white blood cell count, increased blood bilirubin levels, and decreased neutrophil count. In patients with PDGFRA D842V mutations, IRRC- and investigator-assessed ORRs were 75% and 79%, respectively; clinical benefit rates were both 86%. Median duration of response/progression-free survival were not reached. IRCC- and investigator-assessed ORRs in patients in the fourth- or later-line setting were 22% and 35%, respectively. Median progression-free survivals were 5.6 months for both. Overall survival data were immature and not calculated.

CONCLUSION

Avapritinib was generally well tolerated and showed marked anti-tumor activity in Chinese patients with GIST bearing PDGFRA D842V mutations and notable efficacy as fourth- or later-line monotherapy (ClinicalTrials.gov Identifier: NCT04254939).

Ripretinib in advanced gastrointestinal stromal tumors: an overview of current evidence and drug approval

Over the past 20 years, the management of gastrointestinal stromal tumors has acted as an important model in the advancement of molecularly targeted therapies for solid tumors. The success of imatinib has established it as a lasting therapy in the management of early-stage and advanced disease in the first-line setting. Imatinib resistance inevitably develops, resulting in the need for further lines of therapy. Ripretinib is an orally administered switch-control tyrosine kinase inhibitor, specifically developed to target both primary and secondary KIT and PDGFRα resistance mutations. Herein, the authors discuss the molecular rationale, the preclinical evidence and the clinical use of ripretinib in the treatment of gastrointestinal stromal tumors in the advanced stages of disease.

New Drug Approvals for Sarcoma in the Last 5 Years

Sarcoma and locally aggressive connective tissue tumors are a complex group of diseases with a growing number of histotypes in the most recent WHO classification. Most of these tumors are rare (incidence <6/10⁵/y) or ultrarare (<1/10⁶/y). Despite their rarity, sarcomas are often good models for the development of personalized medicine, and a large number of new clinical trials in select histotypes and molecular subsets were reported during the past 5 years, leading to a faster rate of new drug approvals. We analyzed the published literature and the abstracts reported in major congresses dedicated to sarcoma and connective tissue tumor management in the last 5 years. Several targeted therapies, cytotoxic treatments, and immunotherapies have demonstrated activity in dedicated histologic and molecular subtypes of sarcomas. The majority of the studies for ultrarare entities are uncontrolled studies, as a consequence of the rarity of histotypes, but randomized controlled trials were available in the less rare histotypes. Most successful trials were based on biomarker selection, which were often driver molecular alterations, while a large number of ongoing research programs aim to identify biomarkers in parallel to new drug development. Availability of the new agents varies across countries. This article describes the new drugs that made it through to the finish line and new agents with promising activity that are in later stages of investigation in the large family of malignant connective tissue tumors.

Pimitespib in patients with advanced gastrointestinal stromal tumor (CHAPTER-GIST-301): a randomized, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Prognosis of advanced gastrointestinal stromal tumors (GIST) refractory to tyrosine kinase inhibitors (TKIs) is poor. This randomized, placebo-controlled, phase 3 trial evaluated the efficacy and safety of pimitespib, a novel heat shock protein 90 inhibitor, in advanced GIST refractory to standard TKIs.

PATIENTS AND METHODS

Patients with histologically confirmed GIST refractory to imatinib, sunitinib, and regorafenib were randomized 2:1 to oral pimitespib 160 mg/day or placebo for five consecutive days per week in 21-day cycles. Following disease progression by blinded central radiological review (BCRR), crossover to open-label pimitespib was permitted. The primary endpoint was progression-free survival (PFS) by BCRR in the full analysis set. Secondary endpoints included overall survival (OS) adjusted using the rank preserving structural failure time method to reduce the expected confounding impact of crossover.

RESULTS

From Oct 31, 2018 to Apr 30, 2020, 86 patients were randomized to pimitespib (n=58) or placebo (n=28). Median PFS was 2.8 months (95% CI 1.6-2.9) with pimitespib versus 1.4 months (0.9-1.8) with placebo (hazard ratio [HR] 0.51 [95% CI 0.30-0.87]; one-sided p=0.006). Pimitespib showed an improvement in crossover-adjusted OS compared with placebo (HR 0.42 [0.21-0.85], one-sided p=0.007). Seventeen (60.7%) patients receiving placebo crossed-over to pimitespib; median PFS after crossover was 2.7 (95% CI 0.7-4.1) months. The most common (≥30%) treatment-related adverse events (AEs) with pimitespib were diarrhea (74.1%) and decreased appetite (31.0%); the most common (≥10%) grade ≥3 treatment-related AE was diarrhea (13.8%). Treatment-related AEs leading to pimitespib discontinuation occurred in 3 (5.2%) patients.

CONCLUSION

Pimitespib significantly improved PFS and crossover-adjusted OS compared with placebo and had an acceptable safety profile in patients with advanced GIST refractory to standard TKIs.

A multicenter, dose-finding, phase 1b study of imatinib in combination with alpelisib as third-line treatment in patients with advanced gastrointestinal stromal tumor

BACKGROUND

Acquired resistance to approved tyrosine kinase inhibitors limits their clinical use in patients with gastrointestinal stromal tumor (GIST). This study investigated the safety, tolerability and efficacy of alpelisib, a phosphatidylinositol 3-kinase inhibitor, used in combination with imatinib in patients with advanced GIST who had failed prior therapy with both imatinib and sunitinib.

METHODS

This phase 1b, multicenter, open-label study consisted of 2 phases: dose escalation and dose expansion. Dose escalation involved 200 mg once daily (QD) alpelisib, initially, followed by 250 and 350 mg. These were combined with 400 mg QD imatinib until maximum tolerated dose (MTD) and/or a recommended phase 2 dose (RP2D) of alpelisib in combination with imatinib was determined. This MTD/RP2D dose was tested to evaluate the clinical activity of this combination in dose expansion.

RESULTS

Fifty-six patients were enrolled, 21 and 35 in the dose escalation and expansion phases, respectively. The MTD of alpelisib given with imatinib was determined as 350 mg QD. Combination treatment showed partial response in 1 (2.9%) and stable disease in 15 (42.9%) patients. Median progression-free survival was 2 months (95% CI 1.8-4.6). Overall, 92.9% patients had adverse events (AEs) while 46.4% had grade 3/4 AEs, hyperglycemia being the most common (23.2%).

CONCLUSIONS

The MTD of alpelisib was estimated as 350 mg QD when used in combination with imatinib 400 mg QD after oral administration in patients with advanced GIST. The safety and tolerability profile of this combination was acceptable; however, the combination did not demonstrate sufficient clinical activity to justify additional clinical testing.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01735968 (date of initial registration 28/11/2012).

Adjuvant Imatinib in Patients with GIST Harboring Exon 9 KIT Mutations: Results from a Multi-institutional European Retrospective Study

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. Here, the association of dose and other clinicopathologic variables with survival was evaluated in a large multi-institutional European cohort.

EXPERIMENTAL DESIGN

Data from 185 patients were retrospectively collected in 23 European GIST reference centers. Propensity score matching (PSM) and inverse-probability of treatment weighting (IPTW) were used to account for confounders. Univariate and multivariate unweighted and weighted Cox proportional 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 outcomes 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.

Ileal Gastrointestinal Stromal Tumor as a Rare Cause of Gastrointestinal Bleed: A Case Report and Brief Review of the Literature

Gastrointestinal stromal tumors (GISTs) are rare, slowly growing submucosal tumors in the gastrointestinal tract. Due to its indolent nature, GIST can go undetected for a long period of time. Symptomatic patients will typically develop abdominal pain, abdominal fullness, nausea, vomiting, and loss of appetite. However, most commonly and recognizable, patients will have blood in their stool due to rapid bleeding from the tumor. We report a case of a late diagnosis of GIST in the ileum with a favorable outcome.

Impact of adjuvant imatinib on bone and muscle density in patients with resected gastrointestinal stromal tumors

•

By its action on macrophage-colony stimulating factor, imatinib can act on bone microenvironment.

•

Imatinib can influence bone mineral density in patients with chronic myeloid leukemia.

•

The role of imatinib on bone health in GIST patients has not been investigated so far.

•

Imatinib can increase bone mineral density in patients with resected GIST.

Adjuvant treatment with Imatinib is the standard of care for high-risk resected GISTs. Imatinib is known to have an impact on bone mineral density in patients affected by chronic myeloid leukemia, however this effect has never been investigated in GISTs.

We retrospectively evaluated, on CT scans, the effect of adjuvant Imatinib (400 mg/die) on bone mineral density and muscle composition in 14 patients with surgically resected GISTs and in a control group of 8 patients who did not received any treatment. The effect of bone and muscle composition on Imatinib-tolerance was assessed as well.

Overall patients receiving Imatinib experienced an increase in bone mineral density during treatment (p = 0.021); with higher increase in patients with basal values < 120 mg/cm³ (p = 0.002). No changes were observed in the control group (p = 0.918).

Skeletal muscle index and lean body mass did not change over time during Imatinib therapy; however, patients with lower lean body mass and lower body mass index experienced more grade 3 treatment related toxicities (p = 0.024 and p = 0.014 respectively). We also found a non-significant trend between basal BMD and grade 3 toxicities (p = 0.060)

Postoperative Adjuvant Imatinib Therapy-Associated Nomogram to Predict Overall Survival of Gastrointestinal Stromal Tumor

BACKGROUND

Adjuvant imatinib therapy has been shown to improve overall survival (OS) of gastrointestinal stromal tumor (GIST) significantly. Few nomograms combining the use of adjuvant imatinib and clinicopathological characteristics estimate the outcome of patients. We aimed to establish a more comprehensive nomogram for predicting OS in patients with GIST.

METHODS

In total, 1310 GIST patients undergoing curative resection at four high-volume medical centers between 2001 and 2015 were enrolled. Independent prognostic factors were identified by multivariate Cox analysis. Eligible patients were randomly assigned in a ratio of 7:3 into a training set (916 cases) and a validation set (394 cases). A nomogram was established by R software and its predictive power compared with that of the modified National Institutes of Health (NIH) classification using time-dependent receiver operating characteristic (ROC) curves and calibration plot.

RESULTS

Age, tumor site, tumor size, mitotic index, postoperative imatinib and diagnostic delay were identified as independent prognostic parameters and used to construct a nomogram. Of note, diagnostic delay was for the first time included in a prognostic model for GIST. The calibrated nomogram resulted in predicted survival rates consistent with observed ones. And the decision curve analysis suggested that the nomogram prognostic model was clinically useful. Furthermore, time-dependent ROC curves showed the nomogram exhibited greater discrimination power than the modified NIH classification in 3- and 5-year survival predictions for both training and validation sets (all P < 0.05).

CONCLUSIONS

Postoperative adjuvant imatinib therapy improved the survival of GIST patients. We developed and validated a more comprehensive prognostic nomogram for GIST patients, and it could have important clinical utility in improving individualized predictions of survival risks and treatment decision-making.

Preclinical model-based evaluation of Imatinib resistance induced by KIT mutations and its overcoming strategies in gastrointestinal stromal tumor (GIST)

BACKGROUND

The potential correlation between KIT secondary mutations and Imatinib-resistance in gastrointestinal stromal tumor (GIST) has been hinted, yet their specific linkage and underlying mechanisms remained unelucidated, also the development of substitute strategies dealing with this resistance was urgently needed.

METHODS

In this study, we explored the distribution of the most prevalent forms of KIT mutation in Chinese GIST patients, after that, we established cell lines that was overexpressed with mutant KIT, and by performing RNA sequencing, immunoblotting and cell viability, we analyzed their functional and mechanistic relevance with Imatinib-resistance in GIST cell lines. Additionally, we evaluated the tumor inhibition efficacy of four regimens in Imatinib-resistant GIST cell lines and patient-derived xenograft (PDX) models.

RESULTS

We found that KIT exon 13-V654A and exon 17-N822K were the most common secondary mutations in GIST with primary exon 11 mutations. These two secondary mutations induced Imatinib resistance by activating PI3K-Akt signaling pathway, while PI3K-Akt inhibition rescued the resistance. By assessing the feasibility of other four tyrosine kinase inhibitor (TKIs, Sunitinib/Regorafenib/Avapritinib/Ripretinib) against Imatinib-resistant GIST, we found that Sunitinib was more suitable for KIT exon 13 secondary mutations, the rest were more effective for KIT exon 17 secondary mutations, while all four TKIs displayed efficacy for KIT exon 9 mutations, emphasizing their clinical applications against Imatinib resistance.

CONCLUSIONS

We demonstrated the mechanism by which KIT secondary mutations on exon 13/17 cause Imatinib resistance to GIST, and validated that several novel TKIs were valuable therapeutic options against Imatinib-resistance for both secondary- and primary-KIT mutations.

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.

Fibroblast Growth Factor Receptor (FGFR) Signaling in GIST and Soft Tissue Sarcomas

Sarcomas are a heterogeneous group of rare malignancies originating from mesenchymal tissues with limited therapeutic options. Recently, alterations in components of the fibroblast growth factor receptor (FGFR) signaling pathway have been identified in a range of different sarcoma subtypes, most notably gastrointestinal stromal tumors, rhabdomyosarcomas, and liposarcomas. These alterations include genetic events such as translocations, mutations, and amplifications as well as transcriptional overexpression. Targeting FGFR has therefore been proposed as a novel potential therapeutic approach, also in light of the clinical activity shown by multi-target tyrosine kinase inhibitors in specific subtypes of sarcomas. Despite promising preclinical evidence, thus far, clinical trials have enrolled very few sarcoma patients and the efficacy of selective FGFR inhibitors appears relatively low. Here, we review the known alterations of the FGFR pathway in sarcoma patients as well as the preclinical and clinical evidence for the use of FGFR inhibitors in these diseases. Finally, we discuss the possible reasons behind the current clinical data and highlight the need for biomarker stratification to select patients more likely to benefit from FGFR targeted therapies.

Gastrointestinal Stromal Tumors (GISTs): Novel Therapeutic Strategies with Immunotherapy and Small Molecules

Gastrointestinal stromal tumors (GISTs) are the most common types of malignant mesenchymal tumors in the gastrointestinal tract, with an estimated incidence of 1.5/100.000 per year and 1–2% of gastrointestinal neoplasms. About 75–80% of patients have mutations in the KIT gene in exons 9, 11, 13, 14, 17, and 5–10% of patients have mutations in the platelet-derived growth factor receptor a (PDGFRA) gene in exons 12, 14, 18. Moreover, 10–15% of patients have no mutations and are classified as wild type GIST. The treatment for metastatic or unresectable GISTs includes imatinib, sunitinib, and regorafenib. So far, GIST therapies have raised great expectations and offered patients a better quality of life, but increased pharmacological resistance to tyrosine kinase inhibitors is often observed. New treatment options have emerged, with ripretinib, avapritinib, and cabozantinib getting approvals for these tumors. Nowadays, immune checkpoint inhibitors form a new landscape in cancer therapeutics and have already shown remarkable responses in various tumors. Studies in melanoma, non-small-cell lung cancer, and renal cell carcinoma are very encouraging as these inhibitors have increased survival rates. The purpose of this review is to present alternative approaches for the treatment of the GIST patients, such as combinations of immunotherapy and novel inhibitors with traditional therapies (tyrosine kinase inhibitors).

Diarylureas as Antitumor Agents

The diarylurea is a scaffold of great importance in medicinal chemistry as it is present in numerous heterocyclic compounds with antithrombotic, antimalarial, antibacterial, and anti-inflammatory properties. Some diarylureas, serine-threonine kinase or tyrosine kinase inhibitors, were recently reported in literature. The first to come into the market as an anticancer agent was sorafenib, followed by some others. In this review, we survey progress over the past 10 years in the development of new diarylureas as anticancer agents.

Comparative Efficacy and Safety of Different Regimens of Advanced Gastrointestinal Stromal Tumors After Failure Prior Tyrosine Kinase Inhibitors: A Network Meta-Analysis

INTRODUCTION

The prospect of targeted therapies for advanced gastrointestinal stromal tumors (GISTs) has been dramatically transformed after encouraging results achieved in recent clinical trials. At present, the number of second- and third-line treatments are increasing, although the challenge is to take into account the differences between these interventions. Therefore, our goal is to evaluate the investigation of different regimens currently used in GISTs based on findings from phase II or phase III randomized controlled trials (RCTs), and then indirectly compare the effectiveness and safety of the available therapies.

METHODS

The qualified literatures in relevant sources were searched systematically. Studies to identify RCTs of which main endpoints were progression-free survival (PFS), overall survival (OS), and grade 3 or more adverse events (AEs) in patients with GISTs were considered for inclusion.

RESULTS

Eight RCTs met our inclusion criteria, which involved 2351 patients. For PFS, compared with placebo, imatinib, and sunitinib, regorafenib (HR = 0.12, 95% CI 0.07-0.23; HR = 0.27, 95% CI 0.19-0.39; HR = 0.36, 95% CI 0.19-0.72, respectively) and ripretinib (HR = 0.15, 95% CI 0.09-0.25; HR = 0.33, 95% CI 0.16-0.68; HR = 0.44, 95% CI 0.25-0.78, respectively) were significantly correlated with the improvement of PFS, and regorafenib may be the preferred option according to the analysis of treatment rankings. For OS, compared with placebo, imatinib, and sunitinib, masitinib (HR = 0.13, 95% CI 0.04-0.44; HR = 0.13, 95% CI 0.04-0.51; HR = 0.27, 95%CI 0.09-0.84) and ripretinib (HR = 0.36, 95% CI 0.21-0.62; HR = 0.36, 95% CI 0.16-0.80; HR = 0.18, 95% CI 0.09-0.36, respectively) were significantly more effective, and masitinib may be the best choice according to treatment ranking analysis. Statistically, regorafenib can be considered to be the highest in high-grade AEs, while the rate of severe AEs of ripretinib and masitinib was likely the lowest.

CONCLUSION

Our results show that ripretinib has the most favorable balance between effectiveness and tolerability among the different treatment regimens for GISTs.

2-Anilinoquinoline based arylamides as broad spectrum anticancer agents with B-RAFV600E/C-RAF kinase inhibitory effects: Design, synthesis, in vitro cell-based and oncogenic kinase assessments

Prompted by the urgent demand for identification of new anticancer agents with improved potency and efficacy, a new series of arylamides incorporating the privileged 2-anilinoquinoline scaffold has been designed, synthesized, and biologically assessed. Aiming at extensive evaluation of the target compounds' potency and spectrum, a panel of 60 clinically important cancer cell lines representing nine cancer types has been used. Compounds 9a and 9c, with piperazine substituted phenyl ring, emerged as the most active members surpassing the anticancer potencies of the FDA-approved drug imatinib. They elicited sub-micromolar or one-digit micromolar GI₅₀ values over the majority of tested cancer cells including multidrug resistant (MDR) cells like colon HCT-15, renal TK-10 and UO-31, and ovarian NCI/ADR-RES. In vitro mechanistic study showed that compounds 9a and 9c could trigger morphological changes, apoptosis and cell cycle arrest in HCT-116 colon cancer cells. Besides, compound 9c altered microtubule polymerization pattern in a similar fashion to paclitaxel. Kinase screening of 9c disclosed its inhibitory activity over B-RAF^V600E and C-RAF kinases with IC₅₀ values of 0.888 μM and 0.229 μM, respectively. Taken together, the current report presents compounds 9a and 9c as promising broad-spectrum potent anticancer candidates, which could be considered for further development of new anticancer drugs.

Pharmacogenetics in the treatment of gastrointestinal stromal tumors - an updated review

INTRODUCTION

Gastrointestinal stromal tumors (GIST) are the best example of a targeted therapy in solid tumors. The introduction of tyrosine kinase inhibitors (TKIs) deeply improved the prognosis of this tumor. However, a degree of inter-patient variability is still reported in response rates and pharmacogenetics may play an important role in the final clinical outcome.

AREAS COVERED

In this review, the authors provide an updated overview of the pharmacogenetic literature analyzing the role of polymorphisms in both GIST treatment efficacy and toxicity.

EXPERT OPINION

Besides the primary role of somatic DNA in dictating the clinical response to TKIs, several polymorphisms influencing their pharmacokinetics and pharmacodynamics have been identified as being potentially involved. In the last 10 years, many potential biomarkers have been proposed to predict clinical response and toxicity after TKI administration. However, the evidence is still too limited to promote a clinical translation. To date, the somatic mutational status represents the main player in clinical response to TKIs in GIST treatment; however, pharmacogenetics could still explain the degree of inter-patient variability observed in GIST patients. A combination of different theoretical approaches, experimental model systems, and statistical methods is clearly needed, in order to translate pharmacogenetics to clinical practice in the near future.

Dose reduction and discontinuation of standard-dose regorafenib associated with adverse drug events in cancer patients: a systematic review and meta-analysis

Background

Regorafenib (REG) is an oral multikinase inhibitor used in colorectal cancer, gastrointestinal stromal tumour and hepatocellular carcinoma. Several adverse events (AEs) are commonly reported during REG administration, and strategies for managing AEs in everyday clinical practice include supportive care, dose modifications and, when necessary, treatment withdrawal. We performed a systematic review and meta-analysis to assess the schedule treatment modifications of REG associated with AEs across randomized controlled clinical trials (RCTs).

Methods

Eligible studies included RCTs assessing standard dose REG versus placebo. Outcomes of interest included: AE-related permanent discontinuation, dose interruptions and dose reductions.

Results

We retrieved all the relevant RCTs through PubMed/Med, Cochrane library and EMBASE: 7 eligible studies involving a total of 2099 patients (Regorafenib: 1362; placebo: 737) were included in our analysis. The use of REG was associated with higher incidence and risk of all outcomes of interest when compared with placebo. The incidences of permanent discontinuation, dose interruptions and dose reductions in patients receiving REG were 9.7%, 57.2% and 47%, respectively, versus 3.3%, 16.7% and 7.7% of placebo group; compared with placebo, the summary relative risks (RRs) of permanent discontinuation, dose interruptions and dose reductions in REG arm were 2.80 (95% CI 1.85-4.22), 3.21 (95% CI 2.59-3.99) and 6.02 (95% CI 3.28-11.03), respectively.

Conclusions

Treatment with REG at the standard dose of 160 mg is associated with a significant increase in AE-related permanent discontinuation, dose interruptions and dose reductions. Prompt identification and management of AEs seem mandatory to obtain maximal benefit from REG treatment. In the current landscape, dose personalization of REG may have the potential to improve quality of life, minimize treatment discontinuation and maximize patient outcomes.

Chloroquine Combined with Imatinib Overcomes Imatinib Resistance in Gastrointestinal Stromal Tumors by Inhibiting Autophagy via the MAPK/ERK Pathway

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. However, up to 40–50% of GISTs develop secondary resistance after an average of 24 months of imatinib treatment. It has been reported that autophagy can promote the survival of GIST cells and induce drug resistance. Presently, the specific mechanism of autophagy in GISTs with imatinib resistance is not clear.

Materials and Methods

The cell-counting kit (CCK)-8 method and flow cytometry were used for in vitro drug sensitivity testing and autophagy level detection. Detection of the apoptosis level was by flow cytometry with the annexin V Kit. Western blotting was used to analyze the role of autophagy and apoptosis in GIST cells with CQ alone, imatinib alone, or in combination, and to analyze MAPK pathway expression. In vitro results were confirmed by in vivo experiments using the mice model. Hematoxylin and eosin and immunohistochemical staining were used to detect the pathological characteristics and immunophenotype of the transplanted tumor. Detection of KIT and PDGFRA gene mutations in the transplanted imatinib-resistant GIST was done by denaturing high performance liquid chromatography (DHPLC) and direct sequencing. ERK and KIT expression and regulation levels were detected by Western blotting.

Results

In vitro and vivo experiments, the autophagy level of imatinib-resistant cells was higher than that of normal cells; CQ combined with imatinib can promote apoptosis by blocking autophagy of imatinib-resistant cells. In the meanwhile, we found that the phosphorylation level of ERK may be related to autophagy.

Conclusion

Our data suggest that autophagy through the MAPK/ERK pathway may play a pivotal role in imatinib-resistant GIST proliferation. Moreover, combining an autophagy inhibitor with imatinib may be a potential valuable strategy in overcoming acquired resistance in GIST patients.

Prognostic Indicators for Gastrointestinal Stromal Tumors: A Review

Gastrointestinal stromal tumors (GISTs) are potentially malignancies that can occur anywhere in the digestive tract. Tyrosine kinase inhibitors (TKIs) such as imatinib have proven effective since the discovery of KIT and PDGFRA. The current version of NCNN, ESMO and EURACAN guidelines recognized that the three main prognostic factors are the mitotic rate, tumor size and tumor site. In addition, tumor rupture is also recognized as an independent risk factor. However, recent evidence shows that various types of gene mutations are associated with prognosis, and influencing factors such as gastrointestinal bleeding and high Ki67 index have been associated with poor prognosis. It shows that the current risk classification is still insufficient and controversial. With the emergence of more and more lack mutation in KIT/PDGFRA GISTs (KIT/PDGFRA wild-type GISTs) or drug resistance genes, primary and secondary drug resistance problems are caused, which makes the treatment of late or metastatic GIST face challenges. Therefore, this article will review the clinicopathological characteristics of GIST, the special molecular subtypes and other factors that may affect prognosis. We will also explore reliable prognostic markers for better postoperative management and improve the prognosis of patients with GIST.

Revolutions in treatment options in gastrointestinal stromal tumours (GISTs): the latest updates

OPINION STATEMENT

The treatment of advanced GIST is rapidly evolving with the development of novel molecular compounds such as avapritinib and ripretinib, but also promising results have been achieved with cabozantinib in a phase II trial. The availability of over five lines of treatment for patients with advanced GIST is likely to completely shift the current second-line and third-line treatment options, and will also potentially enable a personalised approach to treatment. Imatinib will most likely remain as the first-line treatment of choice for the vast majority of GIST patients. However, for GIST patients with tumours harbouring a D842V mutation in PDGFRA exon 18, avapritinib has shown efficacy and will become first-line therapy for this molecular subgroup. For second- and third-line treatment, results are awaited of a number of clinical trials. However, second-line and further treatment could potentially be tailored depending on secondary mutations found in imatinib-resistant GISTs. As secondary resistance to TKIs remains the biggest challenge in the treatment of GIST and despite negative results with alternating regimens in phase II, combination treatments should be further evaluated to tackle this issue. Moreover, the favourable safety profiles observed with avapritinib and ripretinib suggest that combination treatments are feasible, for instance, combining two TKIs or a TKI with drugs targeting downstream signalling pathways, such as PI3K inhibitors or MEK inhibitors. Finally, in line with further personalisation of treatment in GIST, a multidisciplinary approach is essential, and local treatment options, such as RFA, resection in case of unifocal progression, and radiotherapy, should be considered.

Clinicopathologic and Surgical Characteristics Study of 151 Cases of GIST

BACKGROUND

Gastrointestinal stromal tumor (GIST) is the most appearing mesenchymal tumor of the gastrointestinal system. In this study, we are aiming to share the most up to date knowledge about diagnosis and treatment of these tumors by transferring our clinical experience about GISTs.

METHODS

The 151 patients who were operated between 2006-2020 and whose pathological examination was reported as GIST were analyzed retrospectively. Demographic, clinical, and pathological features and treatment methods of patients were evaluated.

RESULTS

Seeventy-six of the patients were women and 75 of them were men whose age averages were 66.1 (31-86). The most common location was the stomach (55.6%), followed by the small intestine, retroperitoneal, large intestine, rectum, esophagus, and another organ. With surgical intervention, 139 of them had been cured. Twelve of cases were accepted as inoperable. The diameter of tumors in our cases were between 0.4 cm and 35 cm. Determined mitotic activity was ≤ 5 in 71 patients and 5 < in 80 patients. In 8 of 12 unresectable cases, it has been seen that partial remission after the treatment of 12-month tyrosine kinase inhibitors, C-KIT, was positive in 96.7% of our cases. CD34 and Ki-67 was analyzed in patients. CD34 was found positive in 98 (64.9%) of them, Ki-67 was positive in 82 (54.3%) patients. Patients had been observed for 40 months.

CONCLUSION

Despite GISTs are not appearing frequently, nowadays they have started to be seen more frequently than before with the growing present-day diagnostic methods. The ideal treatment is performing radical resection without leaving any tumor cells behind. Tyrosine kinase inhibitors have an important place in unresectable cases.

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.