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.

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.

Prevalence of gastrointestinal stromal tumour (GIST) in the United Kingdom at different therapeutic lines: an epidemiologic model

BACKGROUND

The prevalence of patients with gastrointestinal stromal tumourgst (GIST) who fail currently available treatments imatinib and sunitinib (third-line treatment-eligible GIST) is unknown, but is expected to be below an ultra-orphan disease threshold of 2/100,000 population used in England and Wales. Our study was designed to estimate the prevalence and absolute number of UK patients with unresectable/metastatic GIST at first-, second- and eventually third-line treatment.

METHODS

Our open population model estimates the probability that the prevalence of UK third-line treatment-eligible GIST patients will remain under the ultra-orphan disease threshold. Model parameters for incidence, proportion of unresectable/metastatic disease and survival estimates for GIST patients were obtained from a targeted literature review and a UK cancer register. The robustness of the results was checked through differing scenarios taking extreme values of the input parameters.

RESULTS

The base-case scenario estimated a prevalence of third-line treatment-eligible GIST of 1/100,000 and a prevalence count of 598 with a 99.9% likelihood of being below the ultra-orphan disease threshold. The extreme scenarios, one-way and probabilistic sensitivity analyses and threshold analysis confirmed the robustness of these results.

CONCLUSIONS

The prevalence of third-line treatment-eligible GIST is very low and highly likely below the ultra-orphan disease threshold.

The timing and probability of treatment switch under cost uncertainty: an application to patients with gastrointestinal stromal tumor

BACKGROUND

Cost fluctuations render the outcome of any treatment switch uncertain, so that decision makers might have to wait for more information before optimally switching treatments, especially when the incremental cost per quality-adjusted life year (QALY) gained cannot be fully recovered later on.

OBJECTIVE

To analyze the timing of treatment switch under cost uncertainty.

METHODS

A dynamic stochastic model for the optimal timing of a treatment switch is developed and applied to a problem in medical decision taking, i.e. to patients with unresectable gastrointestinal stromal tumour (GIST).

RESULTS

The theoretical model suggests that cost uncertainty reduces expected net benefit. In addition, cost volatility discourages switching treatments. The stochastic model also illustrates that as technologies become less cost competitive, the cost uncertainty becomes more dominant. With limited substitutability, higher quality of technologies will increase the demand for those technologies disregarding the cost uncertainty. The results of the empirical application suggest that the first-line treatment may be the better choice when considering lifetime welfare.

CONCLUSIONS

Under uncertainty and irreversibility, low-risk patients must begin the second-line treatment as soon as possible, which is precisely when the second-line treatment is least valuable. As the costs of reversing current treatment impacts fall, it becomes more feasible to provide the option-preserving treatment to these low-risk individuals later on.

Insights into cancer surveillance in Central and Eastern Europe, Israel and Turkey

The current cancer landscape within transitional economies in central and Eastern Europe and the Mediterranean area is not particularly optimistic. Current perceptions are often based on extrapolations from other countries and regions; and hence the authors collaborated with the South Eastern Europe Oncology Group (SEEROG) to collect information on cancer registration in Central and Eastern Europe, Israel and Turkey. Healthcare authorities and specialist oncology centres in 21 countries in the region were contacted for information on cancer registries in their countries. Based on this information, the authors believe that the recording and reporting of data on cancer in the region is at an acceptable level. The authors discuss and compare institution- and population-based registries, and present opinions on elements of an 'ideal registry' based on the survey replies and comparisons with other registries. A comparison with the sources used for GLOBOCAN 2008 illustrates the need for consistent data to be communicated, published and utilised throughout the region and the oncology community. The authors conclude by considering the potential value of collaboration between health authorities across the region, as well as between the clinical and epidemiological communities, to ensure that cancer data are consistently collected, verified and made public.

Advances in cancer therapeutics and patient access to new drugs

Globally, there are approximately 7.4 million cancer deaths annually, approximately 13% of deaths from all causes. Cancer is a disease of older people and, as the population ages over the next 10-20 years, we can expect an increase in the cancer incidence. Encouragingly, cancer mortality has stabilized in many countries. Part of this success may be attributed to the development of new cancer agents, collectively called 'targeted therapies', that are more specific to key components of tumour growth. Worldwide, however, one of the main factors that limit patient access to these important new drugs is their cost, which is higher than traditional chemotherapy. In this review, the clinical and pharmacoeconomic data of selected targeted agents are discussed. In the second part of this article, the challenges faced by healthcare systems in making such drugs available to patients is reviewed. Current strategies used by many countries around the world to manage cancer drug budgets are presented, along with a proposed approach using pharmacoeconomic methodology that may increase patient access.

Cost effectiveness of tyrosine kinase inhibitor therapy in metastatic gastrointestinal stromal tumors

BACKGROUND

Tyrosine kinase inhibitors (TKIs) such as imatinib mesylate have revolutionized the treatment of primary unresectable and/or metastatic gastrointestinal stromal tumors (GISTs), providing durable disease control and extended survival. Although most patients eventually progress on therapy, dose escalation has been shown to benefit some patients. Sunitinib, a multitargeted kinase inhibitor is effective against imatinib-resistant or intolerant GIST patients. Although the cost of TKI therapy in GIST is high, no other effective systemic treatment options exist.

OBJECTIVE

Review pharmacoeconomic studies to determine the cost effectiveness (CE) of 1st- and 2nd-line TKI therapies in GIST.

METHODS

A literature review using Medline and PubMed databases was conducted to identify published economic analyses of TKI therapy in GIST. Key results from these studies were analyzed.

RESULTS

Six pharmacoeconomic studies were identified, including three analyses of 1st-line imatinib and three analyses of 2nd-line sunitinib. These studies employed various time horizons and discount rates and modeled CE from a number of different perspectives. Most of the pharmacoeconomic studies reviewed used survival as their efficacy endpoint, projecting outcomes beyond available data to model CE. Analyses of 2nd-line sunitinib using survival additionally faced the challenge of adjusting for the effect of placebo crossover to active treatment in the pivotal phase III study. Most studies used Markov techniques with a range of transition probabilities.

CONCLUSIONS

Published pharmacoeconomic studies of 1st- and 2nd-line TKI therapy for advanced GIST employ various time horizons, discount rates, and different CE models. Consequently, these differences make comparisons between studies difficult. Studies of 1st-line imatinib concluded that imatinib was cost effective in advanced, metastatic GIST. Likewise, based on data reviewed here, 2nd-line sunitinib appears to be cost effective in patients with advanced GIST who are intolerant/resistant to imatinib. Key limitations of this review included inconsistency among the studies evaluated with regard to methodologies, countries of origination (currency and healthcare systems), and patient demographics.