Cost-effectiveness of 3-year vs 1-year adjuvant therapy with imatinib in patients with high risk of gastrointestinal stromal tumour recurrence in the Netherlands; a modelling study alongside the SSGXVIII/AIO trial

Adjuvant imatinib in high-risk resected gastrointestinal stromal tumors: Merely delaying the inevitable?

INTRODUCTION

Patients with high-risk resected gastrointestinal stromal tumors (GIST) receiving adjuvant imatinib have improved recurrence-free survival (RFS), however whether a complete cytocidal effect exists is unknown. We investigated this using a normalized recurrence timeline measured from end of oncologic treatment (EOOT), defined as the later of resection or end of adjuvant therapy.

METHODS

We reviewed patients with resected high-risk GIST at our cancer center from 2003 to 2018. RFS (measured from resection and EOOT), overall survival (OS), and time to imatinib resistance (TTIR) were analyzed using Kaplan-Meier analysis and multivariable Cox proportional hazards modeling. The performance of the Memorial Sloan Kettering (MSK) GIST nomogram was assessed.

RESULTS

We identified 86 patients with high-risk GIST with a median 106 months of postsurgical follow-up. One-third (n = 29; 34%) did not receive adjuvant imatinib, while 57 (66%) did for a median of 3 years. The MSK nomogram-predicted 5-year RFS for patients receiving adjuvant imatinib was similar to those who did not (29% vs. 31%, p = 0.64). When RFS was measured from EOOT, the MSK-predicted RFS was independently associated with EOOT RFS (hazard ratio 0.22, p = 0.02), while adjuvant imatinib receipt and duration were not. Neither receipt nor duration of adjuvant imatinib were associated with TTIR or OS (all p > 0.05).

CONCLUSIONS

Treatment with adjuvant imatinib delays, but does not clearly impact ultimate recurrence, TTIR, or OS, suggesting many patients with high-risk GIST may receive adjuvant imatinib unnecessarily. Additional studies are needed to establish the benefit of adjuvant therapy versus initiating therapy at first radiographic recurrence.

Cost-Effectiveness Analysis of Tyrosine Kinase Inhibitors in Gastrointestinal Stromal Tumor: A Systematic Review

Background: The introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved the clinical effectiveness of patients with locally advanced and/or metastatic gastrointestinal stromal tumors (GIST), and this systematic review was conducted aiming at the cost-effectiveness analysis of TKIs in GIST.

Methods: A thorough literature search of online databases was performed, using appropriate terms such as “gastrointestinal stromal tumor or GIST,” “cost-effectiveness,” and “economic evaluation.” Data extraction was conducted independently by two authors, and completeness of reporting and quality of the evaluation were assessed. The systematic review was conducted following the PRISMA statement.

Results: Published between 2005 and 2020, 15 articles were incorporated into the systematic review. For advanced GIST, imatinib followed by sunitinib was considered cost-effective, and regorafenib was cost-effective compared with imatinib re-challenge therapy in the third-line treatment. For resectable GIST, 3-year adjuvant imatinib therapy represented a cost-effective treatment option. The precision medicine-assisted imatinib treatment was cost-effective compared with empirical treatment.

Conclusion: Although identified studies varied in predicted costs and quality-adjusted life years, there was general agreement in study conclusions. More cost-effectiveness analysis should be conducted regarding more TKIs that have been approved for the treatment of GIST.

Systematic Review Registration:https://www.crd.york.ac.uk/, PROSPERO: CRD42021225253.

Delayed adjuvant imatinib in patients with high risk of recurrence of gastrointestinal stromal tumor after radical surgery: a retrospective cohort study

PURPOSE

To investigate the impact of delayed adjuvant imatinib on GIST patients with high risk of recurrence.

METHOD

Adult GIST patients were retrospectively collected from our hospital between 2011 and 2018, and patients having high risk of recurrence were included for subsequent analyses. The primary endpoint was recurrence-free survival (RFS).

RESULTS

According to the interval between the radical surgery and the beginning of adjuvant imatinib, 222 patients were divided into three groups: group A (≤ 2 months, n = 41), group B (2-≤ 4 months, n = 113), and group C (4-≤ 6 months, n = 68). Univariate, multivariate, and survival analyses all showed that patients in group A had significantly more favorable RFS than those in group C but not group B, and patients taking adjuvant imatinib for over 12 months were also associated with longer RFS comparing to adjuvant imatinib of ≤ 12 months. When stratified by the duration of adjuvant imatinib, no significant differences were found in RFS among groups A, B, and C for adjuvant imatinib of ≤ 12 months. While for adjuvant imatinib of over 12 months, both groups A and B had significantly more favorable RFS than group C, and no significant difference in RFS was found between group A and B.

CONCLUSION

Delayed postoperative adjuvant imatinib for over 4 months in patients with high risk of recurrence of GIST may lead to worse RFS, and longer treatment with shorter delay has best results.

Treatment of gastrointestinal tumor (GIST) of the rectum requiring abdominoperineal resection following neoadjuvant imatinib: a cost-effectiveness analysis

Background

Neoadjuvant imatinib for gastrointestinal stromal tumors (GIST) of the rectum can reduce, but may not eliminate, risk of surgical morbidity from permanent bowel diversion. We sought to evaluate the cost-effectiveness of alternative strategies in rectal GIST patients requiring abdominoperineal resection following neoadjuvant imatinib.

Methods

We developed a Markov model using a healthcare payers' perspective to estimate costs in 2017 Singapore dollars (SGD) and quality adjusted life years (QALYs) for upfront abdominoperineal resection (UAPR) versus continued imatinib until progression (CIUP) following 1 year of neoadjuvant imatinib. Transition probabilities and utilities were obtained from published data, and costs were estimated using data from the National Cancer Centre Singapore. Deterministic and probabilistic sensitivity analyses were conducted to probe model uncertainty. Incremental cost-effectiveness ratio below SGD 50,000 per QALY gained was considered cost-effective.

Results

In the base case, UAPR dominates CIUP being both more effective (8.66 QALYS vs 5.43 QALYs) and less expensive (SGD 312,627 vs SGD 339,011). These estimates were most sensitive to 2 variables, utility of abdominoperineal resection and annual recurrence probability post-abdominoperineal resection. However, simultaneously varying the values of these variables to maximally favor CIUP did not render it the more cost effective strategy at willingness to pay (WTP) of SGD 50,000. In probabilistic sensitivity analysis, UAPR had probability of being cost-effective compared with CIUP greater than 95%, reaching 100% at WTP SGD 10,000.

Conclusion

UAPR is more effective and less costly than CIUP for patients with rectal GIST requiring abdominoperineal resection following neoadjuvant imatinib, and is the strategy of choice in this setting.

Effect of the imatinib treatment regimen on the postoperative prognosis of patients with high-risk gastrointestinal stromal tumors

Background: Surgical resection is the standard treatment for localized and potentially resectable gastrointestinal stromal tumors (GISTs), If the postoperative pathology diagnosis indicates that patients are at high risk of recurrence, they should be treated with imatinib. Even though the introduction of imatinib substantially improved the outcome of GIST patients, it is unclear whether different imatinib treatment regimens affect patients' survival. Methods: This retrospective study included 120 patients who underwent tumor resection for high-risk GISTs between January 2009 and October 2018. The patients were divided into three groups: one group of patients received postoperative imatinib adjuvant therapy regularly (regular treatment group); the second group was not treated with imatinib until they were found to have disease progression (observation group); the third group was treated with postoperative imatinib adjuvant therapy irregularly (irregularly treatment group). The progression-free survival (PFS) and overall survival (OS) were compared between the three groups, and the prognostic risk factors were analysed by the Cox regression model. Results: The median PFS was 45 months (range: 25-59). The 3- and 5-year PFS values were 71.3% and 49.9%, respectively. The PFS in the regular group was longer than in the observation group and irregular group (P<0.001). The median OS was 59 months (range:47-78). The 3- and 5-year OS values were 91.6% and 84.2%, respectively. There were no differences in OS among the three groups (P=0.150). The extent of radical resection (P<0.001) and intraoperative tumor rupture (P=0.005) were independent prognostic factors influencing OS. Conclusions: Irregular administration of imatinib was associated with a worse PFS, but it did not affect the OS of patients with high-risk GISTs. Avoiding intraoperative tumor rupture and R0 resection were associated with better survival.

Cost-utility analysis of adjuvant imatinib treatment in patients with high risk of recurrence after gastrointestinal stromal tumour (GIST) resection in Thailand

Background

Many patients develop tumour recurrence within a few years after undergoing surgical resection of gastrointestinal stromal tumours (GIST). Adjuvant imatinib treatment is recommended for patients with high risk of GIST recurrence as it can improve recurrence-free survival and overall survival of patients. This study aims to assess the cost-utility of adjuvant imatinib in patients with high risk of GIST recurrence after surgery compared with no adjuvant therapy in Thailand.

Methods

A Markov model was developed to estimate lifetime costs and outcomes of using adjuvant imatinib treatment and other treatment alternatives if recurrence occurred compared with the current situation of no adjuvant therapy in high-risk patients after surgery. A 1-month cycle length was deployed in the model. Transition probabilities were derived from literature review. Costs were collected and calculated for the year 2014 from a societal perspective. Future costs and outcomes were discounted at 3% per year. One-way and probabilistic sensitivity analyses were conducted to assess parameter uncertainties.

Results

Three years of adjuvant imatinib treatment followed by imatinib treatment and best supportive care if recurrence occurred after or during adjuvant therapy, respectively, was the best option as it produced more health outcomes (1.23 life years (LYs) and 1.16 quality-adjusted life years (QALYs)) compared to no adjuvant therapy while yielding the lowest incremental cost-effectiveness ratio (ICER) of 1,648,801 Thai Baht (THB) per QALY gained. Three years of adjuvant imatinib treatment followed by sunitinib treatment if recurrence occurred had an ICER of 2,608,264 THB per QALY gained compared to the best option, while other options were dominated. A one-way sensitivity analysis showed that the utility of patients receiving adjuvant imatinib had the greatest effect on the model, followed by the discount rate and probability of GIST recurrence.

Conclusions

Adjuvant imatinib treatment improved the health benefits of patients with high risk of GIST recurrence. However, in the Thai context, it was not cost-effective at the current price.

Management of hemorrhage in gastrointestinal stromal tumors: a review

Gastrointestinal stromal tumors (GISTs) are relatively common mesenchymal tumors. They originate from the wall of hollow viscera and may be found in any part of the digestive tract. The prognosis of patients with stromal tumors depends on various risk factors, including size, location, presence of mitotic figures, and tumor rupture. Emergency surgery is often required for stromal tumors with hemorrhage. The current literature suggests that stromal tumor hemorrhage indicates poor prognosis. Although the optimal treatment options for hemorrhagic GISTs are based on surgical experience, there remains controversy with regard to optimum postoperative management as well as the classification of malignant potential. This article reviews the biological characteristics, diagnostic features, prognostic factors, treatment, and postoperative management of GISTs with hemorrhage.

Distribution-Weighted Cost-Effectiveness Analysis Using Lifetime Health Loss

BACKGROUND

It is widely acknowledged that concerns for the worse off need to be integrated with the concern for cost effectiveness in priority setting, and several countries are seeking to do so. In Norway, a comprehensive framework for priority setting was recently proposed to specify the worse off in terms of lifetime loss of quality-adjusted life-years (QALYs). However, few studies have shown how to calculate such health losses, how to integrate health loss into cost-effectiveness analyses (CEAs) and how such integration impacts the incremental cost-effectiveness ratios (ICERs). The aim of this study was to do so.

METHODS

The proposed framework was applied to data from 15 recent economic evaluations of drugs. Available data were used to calculate the lifetime health loss of the target groups, and the proposed marginal weighting function was employed to adjust standard ICERs according to the size of this loss. Standard and weighted ICERs were compared to a threshold of US$35,000 per QALY gained.

RESULTS

Lifetime health loss can be calculated with the use of available data and integrated by a marginal weighting function with CEAs. Such integration affected standard ICERs to a varying degree and changed the number of interventions considered cost effective from three to eight.

CONCLUSION

Calculation of lifetime health loss and its integration with CEA is feasible and can influence the reimbursement and ranking of interventions. To facilitate regular integration, guidelines for economic evaluations could require (i) adjustment according to distributional concerns and (ii) that data on health loss are extracted directly from the models and reported. Generic databases on health loss could be developed alongside such efforts.

Cost-effectiveness of precision medicine in gastrointestinal stromal tumor and gastric adenocarcinoma

Over the past 20 years, with the incorporation of genetic sequencing and improved understanding regarding the mechanisms of cancer growth/metastasis, novel targets and their associated treatments have emerged in oncology and are now regularly incorporated into the clinical care of patients in the US. Novel, more tumor-specific, non-chemotherapy agents, including agents that are commonly used in the treatment of patients with gastric adenocarcinoma (GA) and gastrointestinal stromal tumor (GIST), fall under a broader treatment strategy, termed "precision medicine". While diagnostic testing and associated treatments in metastatic GA (mGA) are costly and may produce marginal benefit, those associated with GIST, despite being costly, produce significant improvements in patient outcomes. Despite the significant difference in impact, the agents associated with these cancers have similar acquisition costs. In this paper, we will review the current literature regarding cost and cost-effectiveness associated with precision medicine diagnosis and treatment strategies for GA and GIST.

Cost-effectiveness analyses of targeted oral anti-cancer drugs: a systematic review

BACKGROUND

Over the last 15 years, a paradigm shift in oncology has led to the approval of dozens of targeted oral anti-cancer medications (OAMs), which have become the standard of care for certain cancers. While more convenient for patients than infused drugs, the possibility of non-adherence and the frequently high costs of targeted OAMs have proven controversial.

OBJECTIVE

Our objective was to perform the first comprehensive review of cost-effectiveness analyses (CEAs) of targeted OAMs.

METHODS

A literature search in PubMed, The Cochrane Library, and the Health Technology Assessment (HTA) reports published by the National Institute for Health Research HTA Programme in the UK was performed, covering articles published in the 5 years prior to 30 September 2013. Our inclusion criteria were peer-reviewed English-language full-text original research articles with a primary focus on CEA related to targeted OAMs. We categorized these articles by treatment setting (i.e. cancer site/type, line of therapy, and treatment and comparator) and synthesized information from the articles into summary tables.

RESULTS

We identified 41 CEAs covering nine of the 18 targeted OAMs approved by the US FDA as of December 2012. These medications were studied in seven cancers, most often as second-line therapy for advanced-stage patients. In over half of treatment settings where a targeted OAM was compared with treatment that was not a targeted OAM, targeted OAMs were considered cost effective. Limitations in interpreting these findings include the risk of bias due to author conflicts of interest, cross-country variation, and difficulties in generalizing clinical trial evidence to community practice.

CONCLUSIONS

Several types of cost-effectiveness studies remain under-represented in the literature on targeted OAMs, including those for follow-on indications approved after the initial indication for a drug and for off-label indications, head-to-head comparisons of targeted OAMs with other targeted OAMs and targeted intravenous therapies, and studies that adopt a perspective other than the payer's. Keeping up with the increasing number of approved targeted OAMs will also prove an important challenge for economic evaluation.