Immunotherapy with check-point inhibitors (CPI) in adult malignancies: a protocol for the systematic review of the quality of economic analyses

Immuno-oncology has led to a paradigm shift in the field of cancer care. Since its inception, this new class of systemic cancer therapy has received at least 26 Food and Drug Administration (FDA) approvals across 17 different cancer types, with 940 more agents being studied in clinical development as of September 2017 [1].

Contrary to traditional cytotoxic chemotherapy, CPIs enhance the body’s immune system to induce antitumor activity [2]. This allows for comparatively more tolerable adverse events and increased efficacy in certain tumor types. CPIs have been integrated within the treatment pathways of many solid and hematologic malignancies, such as lung and head and neck cancer, urothelial and renal cell carcinoma, and lymphoma. Furthermore, CPIs are under development for use in many more tumor types.

Since healthcare in countries such as Canada and the UK is administered under a publicly funded system, governments have insisted that, prior to approval for funding, new therapies must not only demonstrate clinical effectiveness, but also cost-effectiveness as well. Countries without single-payer systems are also facing the need to account for the rising costs of care. The American Society of Clinical Oncology (ASCO) has recently focused attention on the importance of considering financial impacts in addition to other criteria when assessing new therapies [3]. Thus, along with clinical effectiveness, evaluations of the economic effectiveness of immunotherapies, and in particular check-point inhibitors (CPIs), is of importance.

Unlike the validated approaches for the assessment of clinical effectiveness, such as randomized controlled trials, the assessment of cost-effectiveness is currently not as rigorously scrutinized. Some analyses combine real-world patient-level data with quality of life data collected from randomized controlled trials in single disease sites [4]. Other studies combine multiple disease sites across different countries with inherently different perspectives and healthcare payment systems [5, 6]. Decision-makers often use incremental cost-effectiveness ratios (ICERs) to compare new immunotherapy regimens with existing therapies; however, this method is nuanced and plagued by inaccuracies, such that experts in the field are calling into question the true validity of such analyses [7]. Others have proposed the addition of a standardized scale for grading financial toxicity, parallel to the Common Terminology Criteria for Adverse Events, a system commonly used to evaluate new agents in clinical trials [8].

In an attempt to standardize health economic studies, the International Society of Pharmacoeconomics and Outcomes Research (ISPOR) has developed an aggregate guideline for authors and reviewers to take into consideration. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) Statement was developed by international experts, and jointly endorsed by 10 journals including the British Medical Journal in 2013 [9, 10].

Previous studies have adopted the CHEERS checklist as their reference for evaluating the quality of published health economic studies in multiple settings [11‐13]. In particular, the quality of economic analyses of oral cancer drugs [14], multiple myeloma therapies [15], and adjuvant breast cancer radiotherapy [16], have been assessed in this way. These studies have revealed that adherence to the CHEERS standards was quite variable ranging from 50% to nearly complete compliance.

Although many regulatory bodies have approved immunotherapies based on existing economic analyses, there has not been a review of the quality and reporting of health economic studies conducted on this new class of agents.

Thus, we propose to systematically review the methodologic and reporting quality of cost-effectiveness and cost-utility studies comparing new CPIs used in immune-oncology regimens, including anti-PD1 agents (nivolumab and pembrolizumab), anti-PDL1 agents (atezolizumab, avelumab, and durvalumab), and the anti-CTLA4 agents (ipilimumab and tremelimumab), to established therapies in adults with solid and hematologic malignancies.

This review will not be registered with the international prospective register of systematic reviews (PROSPERO) as it does not meet the eligibility criterion of addressing an outcome of direct patient or clinical relevance.

This protocol was developed based on the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) 2015 checklist (Additional file 1: Figure S1) [17, 18], and any protocol amendments will be described, dated, and a rationale provided.

Only studies meeting the following criteria will be included:

A systematic search will be performed in Ovid MEDLINE® (1946 to present), OVID Embase (1974 to present), Cost-effectiveness Analysis Registry (1926 to 2015), Evidence-Based Medicine Reviews, and NIHR-HTA (1989 to present) with the search strategy detailed in Table 1. Literature search results will be uploaded to EPPI-Reviewer 4 [19], in which two reviewers will independently assess the titles and abstracts of all articles retrieved from the database search. The full-text of articles potentially meeting the inclusion criteria will then be assessed for inclusion by the same two independent reviewers. Neither author will be blinded to the authors, institution, or journal of publication. Any disagreements will be resolved through discussion and consensus between the two reviewers, and a third reviewer will be asked to adjudicate on any cases where consensus cannot be reached. Data will then be extracted from all full-text articles selected for analysis according to the data extraction form detailed in Table 2.

A qualitative description of the quality of included articles will be performed and data extracted (Table 2) will be provided in text and table form. All extracted data will be presented by article in table form. A random effects model will be used to assess the association of journal impact factor, year of publication, funding source, tumor site, trial or model-based study, and check-point-inhibitor studied on compliance with CHEERS criteria. The significance, magnitude, and confidence interval of associations will be presented in table form. Significance will be set at a two-sided p value of ≤ 0.05. All data will be analyzed using STATA 14 (StataCorp. 2015. Stata Statistical Software: Release 14. College Station, TX: StataCorp LP). As the current study focuses on the quality and reporting of economic analyses of CPIs, rather than the reported results, and the high heterogeneity expected of the included studies, no attempts will be made to quantitatively synthesize or analyze the results of the underlying studies, nor the risk of bias of the results, of the included articles. Wherever possible, all results will be presented in accordance with the PRISMA guidelines [20, 21].