Project description:Gastrointestinal stromal tumor (GIST) represents a paradigm for clinically effective targeted inhibition of oncogenic driver mutations in cancer. Five drugs are currently positioned as the standard of care for the treatment of advanced or metastatic GIST patients. This is the result of continuous, deep understanding of KIT and PDGFRA GIST oncogenic drivers as well as the resistance mechanisms associated to tumor progression. However, the complexity of GIST molecular heterogeneity is an evolving field, and critical questions remain open. Specifically, the clinical benefit of approved and/or investigated targeted agents is strikingly modest at advanced stages of the disease when compared with the activity of first-line imatinib. Ripretinib is a novel switch-pocket inhibitor with broad activity against KIT and PDGFRA oncoproteins and has recently demonstrated antitumoral activity across phase I to phase III clinical trials. Therefore, ripretinib has emerged as a new standard of care for advanced, multi-resistant GIST patients. Based on this data, the Food and Drug Administration has granted in 2020 the approval of ripretinib for GIST patients after progression to imatinib, sunitinib and regorafenib. This, in turn, constitutes a major breakthrough in sarcoma drug development, as there have not been new treatment approvals in GIST for nearly a decade. Herein, we provide a critical review on the preclinical and clinical development of ripretinib in GIST. Furthermore, we seek to assess the biological and clinical impact of this new standard of care on the course of the disease, aiming to provide an insight on future treatments strategies for the next coming years.
Project description:BackgroundThe INVICTUS trial assessed the efficacy and safety of ripretinib compared with placebo in the management of advanced gastrointestinal stromal tumors.MethodWe used a Markov model with three health states: progression-free disease, progression disease and death. We parameterized the model from time-to-event data (progression-free survival, overall survival) of ripretinib and placebo arms in the INVICTUS trial and extrapolated to a patient's lifetime horizon. Estimates of health state utilities and costs were based on clinical trial data and the published literature. The outcomes of this model were measured in quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). Uncertainty was tested via univariate and probabilistic sensitivity analyses.ResultsThe base-case model projected improved outcomes (by 0.29 QALYs) and additional costs (by $70,251) and yielded an ICER of $244,010/QALY gained for ripretinib versus placebo. The results were most sensitive to progression rates, the price of ripretinib, and health state utilities. The ICER was most sensitive to overall survival. When overall survival in the placebo group was lower, the ICER dropped to $127,399/QALY. The ICER dropped to $150,000/QALY when the monthly cost of ripretinib decreased to $14,057. Probabilistic sensitivity analyses revealed that ripretinib was the cost-effective therapy in 41.1% of simulations at the willingness-to-pay (WTP) threshold of $150,000.ConclusionAs the fourth- or further-line therapy in advanced gastrointestinal stromal tumors, ripretinib is not cost-effective in the US. Ripretinib would achieve its cost-effectiveness with a price discount of 56% given the present effectiveness.
Project description:PurposeIn advanced gastrointestinal stromal tumor (GIST), there is an unmet need for therapies that target both primary and secondary mutations of pathogenic KIT/PDGFRA oncoproteins. Ripretinib is a novel switch-control kinase inhibitor designed to inhibit a wide range of KIT and PDGFRA mutations.Patients and methodsThis first-in-human, to our knowledge, phase I study of ripretinib (ClinicalTrials.gov identifier: NCT02571036) included a dose-escalation phase and subsequent expansion phase at the recommended phase II dose (RP2D). Eligible patients included those with advanced GIST, intolerant to or experienced progression on ≥ 1 line of systemic therapy, and other advanced malignancies. Safety, dose-limiting toxicities (DLTs), maximum-tolerated dose (MTD), and preliminary antitumor activity were evaluated.ResultsAt data cutoff (August 31, 2019), 258 patients (n = 184 GIST) were enrolled, with 68 patients in the dose-escalation phase. Three DLTs were reported: grade 3 lipase increase (n = 2; 100 mg and 200 mg twice a day) and grade 4 increased creatine phosphokinase (n = 1; 150 mg once daily). MTD was not reached (maximum dose evaluated, 200 mg twice a day); 150 mg once daily was established as the RP2D. The most frequent (> 30%) treatment-emergent adverse events in patients with GIST receiving ripretinib 150 mg once daily (n = 142) were alopecia (n = 88 [62.0%]), fatigue (n = 78 [54.9%]), myalgia (n = 69 [48.6%]), nausea (n = 65 [45.8%]), palmar-plantar erythrodysesthesia (n = 62 [43.7%]), constipation (n = 56 [39.4%]), decreased appetite (n = 48 [33.8%]), and diarrhea (n = 47 [33.1%]). Objective response rate (confirmed) of 11.3% (n = 16/142) ranging from 7.2% (n = 6/83; fourth line or greater) to 19.4% (n = 6/31; second line) and median progression-free survival ranging from 5.5 months (fourth line or greater) to 10.7 months (second line), on the basis of investigator assessment, were observed.ConclusionRipretinib is a well-tolerated, novel inhibitor of KIT and PDGFRA mutant kinases with promising activity in patients with refractory advanced GIST.
Project description:BackgroundRipretinib 150 mg once daily (QD) is indicated for advanced gastrointestinal stromal tumors (GISTs) as at least fourth-line therapy. In INVICTUS, ripretinib intrapatient dose escalation (IPDE) to 150 mg b.i.d. was allowed after progressive disease (PD) on 150 mg QD by blinded independent central review using modified RECIST 1.1. We report the efficacy and safety of ripretinib IPDE to 150 mg b.i.d. after PD among patients randomized to ripretinib 150 mg QD in the INVICTUS study.Materials and methodsTumor imaging was performed every 28-day cycle for the first four cycles in the ripretinib 150 mg QD period and then every other cycle, including the 150 mg b.i.d.PeriodAmong the ripretinib IPDE patients, progression-free survival (PFS)1 was the time from randomization until PD; PFS2 was the time from the first dose of ripretinib 150 mg b.i.d. to PD or death.ResultsAmong 43 ripretinib IPDE patients, median PFS1 was 4.6 months (95% confidence interval [CI], 2.7-6.4) and median PFS2 was 3.7 months (95% CI, 3.1-5.3). Median overall survival was 18.4 months (95% CI, 14.5-not estimable). Ripretinib 150 mg b.i.d. (median duration of treatment 3.7 months) was well tolerated with new or worsening grade 3-4 treatment-emergent adverse events (TEAEs) of anemia in six (14%) and abdominal pain in three (7%) patients. Ripretinib 150 mg b.i.d. was discontinued because of TEAEs in seven (16%) patients.ConclusionRipretinib 150 mg b.i.d. after PD on 150 mg QD may provide additional clinically meaningful benefit with an acceptable safety profile in patients with at least fourth-line GISTs.Implications for practiceOf the 85 patients with advanced gastrointestinal stromal tumor having received at least three prior anticancer therapies randomized to ripretinib 150 mg once daily (QD) in the phase III INVICTUS study, 43 underwent ripretinib intrapatient dose escalation (IPDE) to 150 mg b.i.d. after progressive disease (PD). Median progression-free survival was 4.6 months before and 3.7 months after ripretinib IPDE. The safety profile of ripretinib 150 mg b.i.d. was acceptable. These findings indicate ripretinib IPDE to 150 mg b.i.d. may provide additional clinical benefit in patients with PD on ripretinib 150 mg QD, for whom limited treatment options exist.
Project description:Gastrointestinal stromal tumor is the most common mesenchymal tumor in the gastrointestinal tract and is most frequently developed in the stomach in the form of submucosal tumor. The incidence of gastric gastrointestinal stromal tumor is estimated to be as high as 25% of the population when all small and asymptomatic tumors are included. Because gastric gastrointestinal stromal tumor is not completely distinguished from other submucosal tumors, a surgical excisional biopsy is recommended for tumors >2 cm. The surgical principles of gastrointestinal stromal tumor are composed of an R0 resection with a normal mucosa margin, no systemic lymph node dissection, and avoidance of perforation, which results in peritoneal seeding even in cases with otherwise low risk profiles. Laparoscopic surgery has been indicated for gastrointestinal stromal tumors <5 cm, and the indication for laparoscopic surgery is expanded to larger tumors if the above mentioned surgical principles can be maintained. A simple exogastric resection and various transgastric resection techniques are used for gastrointestinal stromal tumors in favorable locations (the fundus, body, greater curvature side). For a lesion at the gastroesophageal junction in the posterior wall of the stomach, enucleation techniques have been tried preserve the organ's function. Those methods have a theoretical risk of seeding a ruptured tumor, but this risk has not been evaluated by well-designed clinical trials. While some clinical trials are still on-going, neoadjuvant imatinib is suggested when marginally unresectable or multiorgan resection is anticipated to reduce the extent of surgery and the chance of incomplete resection, rupture or bleeding.
Project description:Background Ripretinib was recently approved for the fourth-line targeted therapy for advanced gastrointestinal stromal tumor (GIST) refractory to imatinib, sunitinib, and regorafenib based on the pivotal INVICTUS phase III study. The INVICTUS study demonstrated significantly improved median progression-free survival (PFS) of 6.3 months and an overall survival (OS) insignificant benefit of ripretinib of 15.1 months as compared with placebo in 85 patients with advanced metastatic GIST. However, treatment outcome for the Chinese population, including in Taiwan and Hong Kong, was lacking. Material and Method A compassionate study regarding ripretinib use for patients with advanced/metastatic GIST was conducted from March 2020 to March 2021 to assess the treatment efficacy and safety in Taiwan and Hong Kong patients. Result Twenty evaluable patients (16 men and 4 women) with heavily pretreated metastatic GIST receiving ripretinib from March 2020 to March 2021 were enrolled to evaluate the treatment outcome. The response and clinical benefit rates to ripretinib were 25% (5/20) and 60% (12/20), respectively. The median PFS and OS in this compassionate cohort receiving ripretinib were 6.1 months and not reachable, respectively. Albumin less than 3.5 and disease progression after ripretinib use were the two independent unfavorable factors for PFS. There were 14 out of 20 (70%) experiencing any grade adverse event (AE). Loss of hair is the most common grade I to II AE with an incidence of 55%. Grade III AEs included diarrhea, skin rash, and anemia with one patient (5%) for each AE. Conclusions Late-line ripretinib use in pretreated Taiwan and Hong Kong patients with advanced GIST showed efficacy consistent with the INVICTUS study. Albumin less than 3.5 and disease progression after ripretinib use were the two independent unfavorable factors for PFS. Ripretinib is generally tolerable, with loss of hair being the most common AE.
Project description:The contemporary clinical landscape of gastrointestinal stromal tumor (GIST) has evolved rapidly over the past several years. Widely used treatment guidelines--from the European Society of Medical Oncology (ESMO) and the National Comprehensive Cancer Network--have recently been updated and represent the most up-to-date, comprehensive tools guiding the optimal management of GIST. In these, and in other published guidelines, close alignment among recommendations now exists for many of the clinical issues relevant to GIST management--surgery, use of the tyrosine kinase inhibitors imatinib and sunitinib and the role of pre- and post-operative imatinib, among others. This trend towards a global consensus in the treatment of GIST is the result of a relatively large amount of new data across the spectrum of its management. However, for some clinical considerations, recommendations still partially deviate. This review examines clinical recommendations and opinions on the management of GIST in the context of the latest data in the field and with an eye towards a multidisciplinary approach including surgical oncology, medical oncology, pathology and diagnostic radiology. Points of consensus are highlighted. Expert opinion is presented on management areas where no scientific evidence or firm recommendations currently exist; lingering and unresolved questions or issues are included. Within this framework, we present an evaluation of current global guidelines on the following areas in GIST management: surgery in the metastatic setting; neoadjuvant therapy; adjuvant therapy; mutational analysis; maintenance tyrosine kinase inhibitor therapy; and radiological imaging in GIST. A summary of consensus across these guidelines based on clinical trial data is juxtaposed with expert opinion where gaps in data still remain.
Project description: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.
Project description:Tumor rupture is an important risk factor predictive of recurrence after macroscopically complete resection of gastrointestinal stromal tumors (GISTs), and an indication for defined interval or even lifelong adjuvant therapy with imatinib according to guidelines. However, there is no consensus or universally accepted definition of the term 'tumor rupture', and, consequently, its incidence varies greatly across reported series. Without predefined criteria, the clinical significance of rupture has also been difficult to assess on multivariate analysis of retrospective data. We reviewed the relevant literature and international guidelines, and, based on the Oslo criteria, proposed the following six definitions for 'tumor rupture': (1) tumor fracture or spillage; (2) blood-stained ascites; (3) gastrointestinal perforation at the tumor site; (4) microscopic infiltration of an adjacent organ; (5) intralesional dissection or piecemeal resection; or (6) incisional biopsy. Not all minor defects of tumor integrity should not be classified as rupture, i.e. mucosal defects or spillage contained within the gastrointestinal lumen, microscopic tumor penetration of the peritoneum or iatrogenic damage only to the peritoneal lining, uncomplicated transperitoneal needle biopsy, and R1 resection. This broad definition identifies GIST patients at particularly high risk of recurrence in population-based cohorts; however, its applicability in other sarcomas has not been investigated. As the proposed definition of tumor rupture in GIST has limited evidence based on the small number of patients with rupture in each retrospective study, we recommend validating the proposed definition of tumor rupture in GIST in prospective studies and considering it in clinical practice.