The majority of gastrointestinal stromal tumors (GIST) harbor an activating mutation in either the KIT or PDGFRA receptor tyrosine kinases. Approval of imatinib, a KIT/PDGFRA tyrosine kinase ...inhibitor (TKI), meaningfully improved the treatment of advanced GIST. Other TKIs subsequently gained approval: sunitinib as a second-line therapy and regorafenib as a third-line therapy. However, resistance to each agent occurs in almost all patients over time, typically due to secondary kinase mutations. A major limitation of these 3 approved therapies is that they target the inactive conformation of KIT/PDGFRA; thus, their efficacy is blunted against secondary mutations in the kinase activation loop. Neither sunitinib nor regorafenib inhibit the full spectrum of KIT resistance mutations, and resistance is further complicated by extensive clonal heterogeneity, even within single patients. To combat these limitations, next-generation TKIs were developed and clinically tested, leading to 2 new USA FDA drug approvals in 2020. Ripretinib, a broad-spectrum KIT/PDGFRA inhibitor, was recently approved for the treatment of adult patients with advanced GIST who have received prior treatment with 3 or more kinase inhibitors, including imatinib. Avapritinib, a type I kinase inhibitor that targets active conformation, was approved for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. In this review, we will discuss how resistance mutations have driven the need for newer treatment options for GIST and compare the original GIST TKIs with the next-generation KIT/PDGFRA kinase inhibitors, ripretinib and avapritinib, with a focus on their mechanisms of action.
Gastrointestinal stromal tumours (GISTs) are a paradigm for the development of personalized treatment for cancer patients. The nearly simultaneous discovery of a biomarker that is reflective of their ...origin and the presence of gain-of-function kinase mutations in these tumours set the stage for more accurate diagnosis and the development of kinase inhibitor therapy. Subsequent studies of genotype and phenotype have led to a molecular classification of GIST and to treatment optimization on the basis of molecular subtype. The study of drug-resistant tumours has advanced our understanding of kinase biology, enabling the development of novel kinase inhibitors. Further improvements in GIST treatment may require targeting GIST stem cell populations and/or additional genomic events.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Asciminib, a novel ABL tyrosine kinase inhibitor that targets the myristoyl site of the molecule rather than the ATP-binding domain, showed mainly low-grade toxic effects in a minority of patients ...and considerable antileukemic activity in the majority of those who had resistance to or unacceptable side effects from standard TKIs.
Biology of Gastrointestinal Stromal Tumors CORLESS, Christopher L; FLETCHER, Jonathan A; HEINRICH, Michael C
Journal of clinical oncology,
09/2004, Volume:
22, Issue:
18
Journal Article
Peer reviewed
Once a poorly defined pathologic oddity, in recent years, gastrointestinal stromal tumor (GIST) has emerged as a distinct oncogenetic entity that is now center stage in clinical trials of ...kinase-targeted therapies. This review charts the rapid progress that has established GIST as a model for understanding the role of oncogenic kinase mutations in human tumorigenesis. Approximately 80% to 85% of GISTs harbor activating mutations of the KIT tyrosine kinase. In a series of 322 GISTs (including 140 previously published cases) studied by the authors in detail, mutations in the KIT gene occurred with decreasing frequency in exons 11 (66.1%), 9 (13%), 13 (1.2%), and 17 (0.6%). In the same series, a subset of tumors had mutations in the KIT-related kinase gene PDGF receptor alpha (PDGFRA), which occurred in either exon 18 (5.6%) or 12 (1.5%). The remainder of GISTs (12%) were wild type for both KIT and PDGFRA. Comparative studies of KIT-mutant, PDGFRA-mutant, and wild-type GISTs indicate that there are many similarities between these groups of tumors but also important differences. In particular, the responsiveness of GISTs to treatment with the kinase inhibitor imatinib varies substantially depending on the exonic location of the KIT or PDGFRA mutation. Given these differences, which have implications both for the diagnosis and treatment of GISTs, we propose a molecular-based classification of GIST. Recent studies of familial GIST, pediatric GIST, and variant forms of GIST related to Carney's triad and neurofibromatosis type 1 are discussed in relationship to this molecular classification. In addition, the role of mutation screening in KIT and PDGFRA as a diagnostic and prognostic aid is emphasized in this review.
Resistance to approved inhibitors of KIT proto-oncogene, receptor tyrosine kinase (KIT), and platelet-derived growth factor receptor α (PDGFRA) is a clinical challenge for patients with advanced ...gastrointestinal stromal tumours. We compared the efficacy and safety of ripretinib, a switch-control tyrosine kinase inhibitor active against a broad spectrum of KIT and PDGFRA mutations, with placebo in patients with previously treated, advanced gastrointestinal stromal tumours.
In this double-blind, randomised, placebo-controlled, phase 3 study, we enrolled adult patients in 29 specialised hospitals in 12 countries. We included patients aged 18 years or older who had advanced gastrointestinal stromal tumours with progression on at least imatinib, sunitinib, and regorafenib or documented intolerance to any of these treatments despite dose modifications, and who had an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2. Eligible patients were randomly assigned (2:1) to receive either oral ripretinib 150 mg once daily (ripretenib group) or placebo once daily (placebo group). Randomisation was done via an interactive response system using randomly permuted block sizes of six and stratified according to number of previous therapies and ECOG performance status. Patients, investigators, research staff, and the sponsor study team were masked to a patient's treatment allocation until the blinded independent central review (BICR) showed progressive disease for the patient. The primary endpoint was progression-free survival, assessed by BICR. The primary analysis was done in the intention-to-treat population and safety was assessed in patients who received at least one dose of study drug. Patients randomly assigned to placebo were permitted to cross over to ripretinib 150 mg at the time of disease progression. The INVICTUS study is registered with ClinicalTrials.gov, number NCT03353753, and with WHO International Clinical Trials Registry Platform, number EUCTR2017-002446-76-ES; follow-up is ongoing.
Between Feb 27, 2018, and Nov 16, 2018, 129 of 154 assessed patients were randomly assigned to receive either ripretinib (n=85) or placebo (n=44). At data cutoff (May 31, 2019), at a median follow-up of 6·3 months (IQR 3·2–8·2) in the ripretinib group and 1·6 months (1·1–2·7) in the placebo group, 51 patients in the ripretinib group and 37 in the placebo group had had progression-free survival events. In the double-blind period, median progression-free survival was 6·3 months (95% CI 4·6–6·9) with ripretinib compared with 1·0 months (0·9–1·7) with placebo (hazard ratio 0·15, 95% CI 0·09–0·25; p<0·0001). The most common (>2%) grade 3 or 4 treatment-related treatment-emergent adverse events in the ripretinib group (n=85) included lipase increase (four 5%), hypertension (three 4%), fatigue (two 2%), and hypophosphataemia (two (2%); in the placebo group (n=43), the most common (>2%) grade 3 or 4 treatment-related treatment-emergent adverse events were anaemia (three 7%), fatigue (one 2%), diarrhoea (one 2%), decreased appetite (one 2%), dehydration (one 2%), hyperkalaemia (one 2%), acute kidney injury (one 2%), and pulmonary oedema (one 2%). Treatment-related serious adverse events were reported in eight (9%) of 85 patients who received ripretinib and three (7%) of 43 patients who received placebo. Treatment-related deaths occurred in one patient in the placebo group (septic shock and pulmonary oedema) and one patient in the ripretinib group (cause of death unknown; the patient died during sleep).
Ripretinib significantly improved median progression-free survival compared with placebo and had an acceptable safety profile in patients with advanced gastrointestinal stromal tumours who were resistant to approved treatments.
Deciphera Pharmaceuticals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gastrointestinal stromal tumors (GISTs) form an interesting group of sarcomas whose unique pathobiology provides a model of how molecularly targeted therapeutics can have a major impact on patient ...welfare. Approximately 85% of GISTs are driven by oncogenic mutations in either of two receptor tyrosine kinases: KIT or platelet-derived growth factor receptor alpha. We review the pivotal relationship between specific mutations in these kinase genes, the origin and pathologic spectrum of GISTs, and the response of these tumors to treatment with kinase inhibitors such as imatinib and sunitinib. Mechanisms of resistance to kinase inhibitor therapy are discussed, and targets for the next generation of therapeutics are considered. The rapid evolution in our understanding of GISTs, which stems directly from the close alliance of basic and clinical researchers in the field, illustrates the growing role of the molecular classification of solid tumors in the development of modern oncological treatments.
To review the epidemiology, presentation, diagnosis, and management of head and neck paragangliomas.
A literature review of english language papers with focus on most current literature.
...Paragangliomas (PGLs) are a group of neuroendocrine tumors that arise in the parasympathetic or sympathetic ganglia. Head and neck PGLs (HNPGLs) comprise 65% to 70% of all PGLs and account for 0.6% of all head and neck cancers. The majority of HNPGLs are benign, and 6% to 19% of all HNPGLs develop metastasis outside the tumor site and significantly compromise survival. PGLs can have a familial etiology with germline sequence variations in different susceptibility genes, with the gene encoding succinate dehydrogenase being the most common sequence variation, or they can arise from somatic sequence variations or fusion genes. Workup includes biochemical testing to rule out secretory components, although it is rare in HNPGLs. In addition, imaging modalities, such as computed tomography and magnetic resonance imaging, help in monitoring in surgical planning. Functional imaging with DOTATATE-positron emission tomography, 18F-fluorodeoxyglucose, or 18F-fluorohydroxyphenylalanine may be necessary to rule out sites of metastases. The management of HNPGLs is complex depending on pathology, location, and aggressiveness of the tumor. Treatment ranges from observation to resection to systemic treatment. Similarly, the prognosis ranges from a normal life expectancy to a 5-year survival of 11.8% in patients with distant metastasis.
Our review is a comprehensive summary of the incidence, mortality, pathogenesis, presentation, workup and management of HNPGLs.
Gastrointestinal stromal tumors (GIST) are the most common type of sarcoma in the gastrointestinal tract. Surgery is the primary
treatment modality, but many patients suffer disease recurrence or ...metastasis. Fortunately, the management of advanced GIST
has been revolutionized by the use of small molecule kinase inhibitors that target the underlying pathogenetic mutant kinases
found in the vast majority of cases. Approximately 85% of GISTs have oncogenic mutations in KIT, allowing for constitutive
kinase activation that is responsible for cellular proliferation and survival. About 5 to 7% of GISTs have activating mutations
of the homologous platelet-derived growth factor receptor alpha (PDGFRA) kinase. The progression-free and overall survival
of patients with advanced disease is greatly improved by treatment with the kinase inhibitors imatinib and sunitinib. However,
the emergence of drug-resistant tumor clones limits the long-term benefit of these drugs in most patients. Resistance to these
kinase inhibitors is associated with distinctive clinical and molecular features, with the development of secondary mutations
of the oncogenic kinase being the most common mechanism. We review the molecular basis of GIST response and/or resistance
to TKIs, and discuss strategies to prevent and/or overcome drug resistance. These concepts are directly relevant to the development
of targeted molecular therapy for other solid tumors. (Clin Cancer Res 2009;15(24):7510–8)
Ripretinib (DCC-2618) was designed to inhibit the full spectrum of mutant KIT and PDGFRA kinases found in cancers and myeloproliferative neoplasms, particularly in gastrointestinal stromal tumors ...(GISTs), in which the heterogeneity of drug-resistant KIT mutations is a major challenge. Ripretinib is a “switch-control” kinase inhibitor that forces the activation loop (or activation “switch”) into an inactive conformation. Ripretinib inhibits all tested KIT and PDGFRA mutants, and notably is a type II kinase inhibitor demonstrated to broadly inhibit activation loop mutations in KIT and PDGFRA, previously thought only achievable with type I inhibitors. Ripretinib shows efficacy in preclinical cancer models, and preliminary clinical data provide proof-of-concept that ripretinib inhibits a wide range of KIT mutants in patients with drug-resistant GISTs.
•Ripretinib broadly inhibits primary and drug-resistant KIT/PDGFRA mutants•KIT/PDGFRA inhibitor of all known activation loop mutations•In drug-resistant cancers, ripretinib blocks kinase signaling and tumor growth•Circulating tumor DNA data confirm broad inhibition of mutant KIT in GIST patients
To overcome the often multi-subclonal mutations in treatment-resistant GIST, Smith et al. design ripretinib, which targets a broad spectrum of KIT and PDGFRA mutants. Ripretinib shows efficacy in KIT and PDGFRA mutant cancer models and reduces circulating tumor DNA mutant allele frequency in two GIST patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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