An exploratory case study of the impact of expanding cost-effectiveness analysis for second-line nivolumab for patients with squamous non-small cell lung cancer in Canada: Does it make a difference?

On spillovers in economic evaluations: definition, mapping review and research agenda

An important issue in economic evaluations is determining whether all relevant impacts are considered, given the perspective chosen for the analysis. Acknowledging that patients are not isolated individuals has important implications in this context. Increasingly, the term "spillovers" is used to label consequences of health interventions on others. However, a clear definition of spillovers is lacking, and as a result, the scope of the concept remains unclear. In this study, we aim to clarify the concept of spillovers by proposing a definition applicable in health economic evaluations. To illustrate the implications of this definition, we highlight the diversity of potential spillovers through an expanded impact inventory and conduct a mapping review that outlines the evidence base for the different types of spillovers. In the context of economic evaluations of health interventions, we define spillovers as all impacts from an intervention on all parties or entities other than the users of the intervention under evaluation. This definition encompasses a broader range of potential costs and effects, beyond informal caregivers and family members. The expanded impact inventory enables a systematic approach to identifying broader impacts of health interventions. The mapping review shows that the relevance of different types of spillovers is context-specific. Some spillovers are regularly included in economic evaluations, although not always recognised as such, while others are not. A consistent use of the term "spillovers", improved measurement of these costs and effects, and increased transparency in reporting them are still necessary. To that end, we propose a research agenda.

Can Generalized Cost-Effectiveness Analysis Leverage Meaningful Use of Novel Value Elements in Pharmacoeconomics to Inform Medicare Drug Price Negotiation?

OBJECTIVES

Decision makers considering using cost-effectiveness analysis (CEA) to inform health-technology assessment must contend with documented and controversial shortfalls of CEA, including its assumption of disease severity independence and static pricing. ISPOR has recently introduced novel value elements besides direct healthcare cost and effectiveness for the patient, and these should be captured in CEA. Although novel value elements advance our understanding of "what" should be measured (value of hope, severity of disease, health equity, etc), there is limited direction on "how" to measure them in conventional CEA. Furthermore, with Medicare empowered to set drug prices under the Inflation Reduction Act, it is not clear what role CEA might have on where prices are set, given objections to the quality-adjusted life year in conventional approaches.

METHODS

We critically reviewed the evidence for expanding conventional CEA methods to a more generalized approach of generalized CEA (GCEA).

RESULTS

GCEA accounts for methods that address objections to the quality-adjusted life year and incorporate novel value elements. Although GCEA offers advantages, it also requires further research to develop "off-the-shelf" resources to help inform, for example, maximum fair price in the context of Medicare drug price negotiation.

CONCLUSIONS

Should a shift toward GCEA reveal that the societal value of novel medicines exceeds their market-based costs, which will raise the key question of what market failure Medicare negotiation is meant to solve, if any, and therefore what the appropriate role of such negotiation might be to maximize the value society might garner from the development of novel medicines.

Sensitivity Analysis in Economic Evaluations of Immuno-Oncology Drugs: A Systematic Literature Review

OBJECTIVES

This study aimed to review, assess, and report the characteristics and strategies of sensitivity analyses (SAs) that were performed in the context of published economic evaluations of immuno-oncology drugs.

METHODS

The systematic literature search was conducted in Scopus and MEDLINE for articles published from 2005 to 2021. Study selection, based on a predefined set of criteria, was performed by 2 reviewers independently. We included economic evaluations of Food and Drug Administration-approved immuno-oncology drugs that were published in English and assessed the accompanying SAs on a set of items, including the range justification of the baseline parameters within the deterministic SA, the provisions for the correlation/overlay between parameters, and the justification of the chosen parameter distribution for the probabilistic SA, among others.

RESULTS

A total of 98 of 295 publications met the inclusion criteria. A total of 90 studies included a one-way and probabilistic SA and 16 of 98 studies had one-way and scenario analysis, alone or together with probabilistic analysis. Most studies provide explicit references as to the choice of parameters and values; nevertheless, there is a lack of a reference of correlation/overlay between parameters in most of the evaluations. In 26 of 98 studies, the most influential parameter for the incremental cost-effectiveness ratio was the under-evaluation drug cost.

CONCLUSIONS

Most of included articles contained an SA that was implemented according to commonly accepted published guidance. The under-evaluation drug cost, the estimates of progression-free survival, the hazard ratio for overall survival, and the time horizon of the analysis seem to play an important part in the robustness of the outcomes.

Economic Evaluation of Nivolumab Versus Docetaxel for the Treatment of Advanced Squamous and Non-squamous Non-small Cell Lung Cancer After Prior Chemotherapy in China

OBJECTIVE

To evaluate the economic value of nivolumab versus docetaxel for advanced non-small cell lung cancer (aNSCLC) treatment after platinum-based chemotherapy in adults without epidermal growth factor receptor/anaplastic lymphoma kinase aberrations in China.

METHODS

Partitioned survival models evaluated lifetime costs and benefits of nivolumab versus docetaxel by squamous and non-squamous histologies from a Chinese healthcare payer perspective. Progression-free disease, progressed disease, and death health states were considered over a 20-year time horizon. Clinical data were derived from the CheckMate pivotal Phase III trials (ClinicalTrials.gov identifiers: NCT01642004, NCT01673867, NCT02613507); patient-level survival data were extrapolated using parametric functions. China-specific health state utilities, healthcare resource utilisation, and unit costs were applied. Sensitivity analyses explored uncertainty.

RESULTS

Nivolumab resulted in extended survival (1.489 and 1.228 life-years [1.226 and 0.995 discounted]) and quality-adjusted survival benefits (1.034 and 0.833 quality-adjusted life-years) at additional costs of ¥214,353 (US$31,829) and ¥158,993 (US$23,608) versus docetaxel in squamous and non-squamous aNSCLC, respectively. Nivolumab was associated with higher acquisition costs, lower subsequent treatment costs, and lower adverse event management costs than docetaxel in both histologies. Drug acquisition costs, discount rate for outcomes, and average body weight were key model drivers. Stochastic results aligned with the deterministic results.

CONCLUSIONS

Nivolumab yielded survival and quality-adjusted survival benefits at incremental cost versus docetaxel in aNSCLC. As a traditional healthcare payer perspective was applied, the true economic benefit of nivolumab may be underestimated as not all treatment benefits and costs of relevance to society were considered.

Incorporating risk preferences of patients in the valuation of immune checkpoint inhibitors for non-small cell lung cancer

Immunotherapy offers a distinctive mechanism of action compared to traditional treatments, arising from additional value dimensions that may not be captured in standard health technology assessments. Cancer patients may have the expectation that immunotherapy provides durable, long-term survival gains. Moreover, some patients may be willing to take a 'risk' to undergo immunotherapy to achieve better survival outcomes. We reviewed quantitative methods that explored patients' risk preferences in their non-small cell lung cancer (NSCLC) treatment choices, in PubMed (MEDLINE), from January 1, 2015, until July 1, 2022. The consideration of a value dimension ('hope') based on patients' risk-seeking preferences is specifically addressed for the valuation of immune checkpoint inhibitors in NSCLC. We reported that the quantitative methods that aim to measure patients' risk preferences or 'hope' empirically are emerging. Value assessments should not only comprise survival improvements for the mean or median patient but also consider methods that reflect durable, long-term overall survival gains for risk-seeking patients. However, the published evidence for incorporating 'hope' based on patients' stated preferences for uncertain treatment profiles is not strong, and future research could strengthen this evidence base. We encourage further research on the development and validation of quantification methods to incorporate 'hope' and risk preferences of patients treated with immunotherapy for NSCLC and beyond.

Cost-Effectiveness Analysis of Olaparib in Combination with Bevacizumab Compared with Bevacizumab Monotherapy for the First-Line Maintenance Treatment of Homologous Recombination Deficiency-Positive Advanced Ovarian Cancer

BACKGROUND

In the PAOLA-1 trial, olaparib plus bevacizumab demonstrated significant clinical benefit following partial or complete response to platinum-based chemotherapy in homologous recombination deficiency (HRD)-positive ovarian cancer. Our study evaluated the cost effectiveness of olaparib plus bevacizumab compared with bevacizumab alone as a maintenance treatment for women in this population.

METHODS

Our model was a cohort-level partitioned survival model with a lifetime horizon from a US healthcare system perspective. Its four health states were progression-free, post first progression, post second progression, and death, modeled using time to first progression (PFS1), second progression (PFS2), and overall survival (OS) from PAOLA-1. We modeled PFS1 through mixture survival modeling, and PFS2 and OS by fitting standard parametric models. Time-on-treatment was sourced directly from PAOLA-1, with treatment capped at 24 months for olaparib and 15 months for bevacizumab. Costs included drug acquisition and administration, adverse events, disease management, biomarker testing, and subsequent treatments. Deterministic and probabilistic sensitivity analyses tested the results.

RESULTS

Compared with bevacizumab alone, olaparib plus bevacizumab increased quality-adjusted life-years (QALYs; +2.89) and life-years (LYs; +3.43) at an incremental cost of $164,209, leading to an incremental cost-effectiveness ratio of $56,863 per QALY. Olaparib plus bevacizumab had a 97.0% probability of being cost effective compared with bevacizumab alone at a willingness-to-pay threshold of $100,000 per QALY.

CONCLUSION

The addition of olaparib to bevacizumab led to clinically significant increases in progression-free survival, resulting in substantial predicted LYs and QALYs gained, while being cost effective in the maintenance treatment of advanced ovarian cancer with HRD in the US.

Should We Consider Including a Value for "Hope" as an Additional Benefit Within Health Technology Assessment?

Health technology assessment (HTA) typically uses average health-related quality of life gain as its main measure of benefit used in economic evaluation. Nevertheless, there have been calls to consider novel aspects of benefit including the "value of hope," defined as a patients' potential preferences for a wider distribution of treatment benefit with a positive skew, in the hope that they will be one of the lucky ones. The value of hope may also derive from feeling hopeful as a positive mental state, which may be missing from current measures of health-related quality of life. The value attributed to feeling hopeful could be related to, or additional to, the value derived from possible risk-seeking preferences. Here, we reflect upon the strength of the case for the inclusion of the "value of hope" taking a critical look at the commonly referenced evidence for including the "value of hope" as risk-seeking preferences. We also draw attention to other conceptions of hope-as an emotion, a cognitive process, or a combination of both-and reflect upon the potential of including these broader notions of hope into HTA. The case for the inclusion of the "value of hope" based on risk-seeking preferences is weak. We suggest research questions that could give further evidence on whether hope is an important missing value from HTA.

The History and Future of the "ISPOR Value Flower": Addressing Limitations of Conventional Cost-Effectiveness Analysis

OBJECTIVES

Since its publication as part of the 2018 ISPOR Special Task Force (STF) on US Value Assessments, the "ISPOR value flower," with its petals highlighting elements that may be overlooked or underappreciated in conventional drug value assessments, has been discussed and debated. We review the history of the value flower, describe recent developments, and consider implications for future value assessments.

METHODS

We discuss various antecedents to the value flower, as well as conceptual and empirical articles published in the past 4 years.

RESULTS

Since the publication of the ISPOR STF report, researchers have provided more rigorous theoretical and mathematical foundations for certain novel value elements (eg, severity of illness, value of insurance, value of hope) through "generalized risk-adjusted cost-effectiveness analysis," which incorporates risk aversion in people's preferences and uncertainty in treatment outcomes. Empirical estimates are also emerging to support key elements, such as insurance value, real option value, value of hope, and value of knowing. Although health technology assessment bodies have applied or are considering certain elements (eg, severity modifiers to cost-effectiveness thresholds), other elements have yet to gain traction.

CONCLUSIONS

Five years after the STF began its work, the development of novel value measures continues to evolve. Although it is encouraging to see supporting empirical studies emerging, more are needed. Additional efforts are also needed to illustrate how the estimates can be used in the deliberative processes that are integral to health technology assessments.

Valuing treatment in oncology: embracing a broader notion of value

Over the past decade, we have witnessed unprecedented, groundbreaking innovation in pharmaceuticals. This has been particularly true in oncology, where new therapies have increased survival and at times offered clinical cure. However, the impact of these promising treatments has been attenuated by persistent access and cost challenges that may limit their effect. A narrative has emerged that many of these so-called breakthroughs are not priced according to the value they provide. Traditional cost-effectiveness analyses would appear to support these doubts, often suggesting that innovative therapies do not represent value for money. However, there is a case to be made that innovative therapies require equally innovative value assessments. To explore this emerging viewpoint, this article provides a brief introduction to the current value debate and oncology-specific considerations when assessing elements of value. We offer a brief background on the nature and development of quality-adjusted life-years as a part of cost-effectiveness analyses and some of their key limitations; a primer on "novel" elements of value, which capture specific aspects of patient and societal preferences not included in quality-adjusted life-years; and their applicability to oncology including discussion on areas where further thought and research might be needed. We conclude with a potential checklist of novel elements of value that should be considered. DISCLOSURES: This Viewpoints article was funded by Novartis, Inc., which also provided funding to COVIA Health Solutions for manuscript development. The sponsor was involved in developing the manuscript. Kamal-Bahl and Puckett are employees of COVIA Health Solutions, a consulting firm that provides services to biopharmaceutical clients, trade organizations, and foundations. Kamal-Bahl holds stock in Merck and Pfizer. Singh is an employee of Novartis Pharmaceuticals. Willke received personal fees from COVIA Health Solutions for work on the manuscript.

Broadening the Concept of Value: A Scoping Review on the Option Value of Medical Technologies

OBJECTIVES

A recent debate in health economics and outcomes research community identified option value as one of the elements warranting consideration in the assessment of medical technologies. To conduct a scoping review of contributions on option value in the healthcare sector and identify relevant conceptual aspects and methods used to incorporate it in standard economic evaluations.

METHODS

A systematic search was conducted up to July 2020 to identify contributions from electronic bibliographic database and gray literature. Data on the proposed definitions of option value, theoretical implications of its use in economic evaluations, and methods used to estimate it were extracted and analyzed.

RESULTS

We found 57 eligible studies. Three different definitions emerged: insurance value, real option value, and option value of survival. Focusing on the latter (24 studies), we analyzed in depth 8 empirical applications across 7 therapeutic areas. The most relevant methodological challenges were on the perspective used in economic evaluations and how to robustly manage forecasting uncertainty, update cost-effectiveness thresholds, and avoid double-counting issues. For empirical studies assessing the total value of the technology, including option value, estimates ranged from +7% to +469% of its conventional value.

CONCLUSIONS

This review synthesizes theoretical and empirical aspects on option value of healthcare technologies and proposes a terminology to distinguish 3 different concepts identified. Future work should focus primarily on agreeing on whether option value should be included in economic evaluations and, if so, on developing and validating reliable methods for its ex-ante estimation.

Measuring the Value Healthy Individuals Place on Generous Insurance Coverage of Severe Diseases: A Stated Preference Survey of Adults Diagnosed With and Without Lung Cancer

OBJECTIVES

To compare the ex ante willingness to pay (WTP) of healthy individuals for generous insurance coverage of novel lung cancer treatments to the WTP for coverage of such treatment among individuals with lung cancer.

METHODS

A survey was administered to 2 cohorts of US adults: (1) healthy individuals without cancer and (2) individuals diagnosed with lung cancer. A multiple random staircase survey design was used to elicit respondent WTP for coverage of novel lung cancer therapy associated with survival gains.

RESULTS

Of the 84 937 healthy individuals invited, 300 completed the survey. Of the 36 249 in the lung cancer cohort invited, 250 completed the survey. Mean age by cohort was 50.0 (SD 14.6) and 48.4 (SD 16.8) years, and 55.2% and 47.2% were female, respectively. Respondents in the healthy and lung cancer cohorts were willing to pay $97.52 (95% confidence interval (CI) $89.89-$105.15) and $22 304 (95% CI $20 194-$24 414) per month, respectively, for coverage of a novel therapy providing 5-year survival of 15% versus standard-of-care therapy with a 5-year survival of 4%. After accounting for the likelihood that healthy individuals are diagnosed with lung cancer in the future, we estimated that 89.8% of the total value of new lung cancer treatments comes from the WTP healthy individuals place on generous insurance coverage.

CONCLUSIONS

Total societal willingness to pay for lung cancer is much higher than conventionally thought, as most healthy individuals are risk-averse and highly value having lung cancer treatments available to them in the future.

Net benefit separation and the determination curve: A probabilistic framework for cost-effectiveness estimation

Considerations regarding clinical effectiveness and cost are essential in comparing the overall value of two treatments. There has been growing interest in methodology to integrate cost and effectiveness measures in order to inform policy and promote adequate resource allocation. The net monetary benefit aggregates information on differences in mean cost and clinical outcomes; the cost-effectiveness acceptability curve was developed to characterize the extent to which the strength of evidence regarding net monetary benefit changes with fluctuations in the willingness-to-pay threshold. Methods to derive insights from characteristics of the cost/clinical outcomes besides mean differences remain undeveloped but may also be informative. We propose a novel probabilistic measure of cost-effectiveness based on the stochastic ordering of the individual net benefit distribution under each treatment. Our approach is able to accommodate features frequently encountered in observational data including confounding and censoring, and complements the net monetary benefit in the insights it provides. We conduct a range of simulations to evaluate finite-sample performance and illustrate our proposed approach using simulated data based on a study of endometrial cancer patients.

Effectiveness and cost-effectiveness analysis of nimotuzumab for the radiotherapy of locoregionally advanced nasopharyngeal carcinoma

BACKGROUND

This study aimed to assess the effectiveness and cost-effectiveness of nimotuzumab in patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC).

METHODS

LA-NPC patients treated between October 2013 and December 2016 were retrospectively reviewed. A well-balanced cohort of patients who received nimotuzumab in addition to standard treatment (n = 50) and patients who did not receive nimotuzumab (n = 100) was selected using propensity score-matching method (1:2 ratio) for the cost-effectiveness analysis.

RESULTS

Compared with concurrent chemoradiotherapy (CCRT) alone, addition of nimotuzumab to CCRT significantly improved the 3-year overall survival (OS) (98.00% vs. 91.00%, P = 0.032). On multivariate analysis, nimotuzumab (hazard ratio = 0.124, 95% confidence interval: 0.017-0.902, P = 0.039) showed prognostic significance for OS. No serious treatment-related adverse events were observed in the nimotuzumab group (P > 0.05). Cost-effectiveness analysis revealed that addition of nimotuzumab increased the average treatment costs by $14,364.63. The additional cost for every one percent increase in OS rate was $ 2,052.09.

CONCLUSION

Addition of nimotuzumab to CCRT for LA-NPC confers significant survival benefits; however, it is not cost-effective.

Economic evaluations of cancer immunotherapy: a systematic review and quality evaluation

OBJECTIVES

Scientific advances in the last decade have highlighted the use of immunotherapy, especially immune checkpoint inhibitors, to be an effective strategy in cancer therapy. However, these immunotherapeutic agents are expensive, and their use must take into account economic criteria. Thus, the objective of the present study was to systematically identify and review published EE related to the use of ipilimumab, nivolumab or pembrolizumab in melanoma, lung cancer, head and neck cancer or renal cell carcinoma, and to assess their quality.

METHODS

The systematic literature research was conducted on Medline via PubMed and the Cochrane Central Register of Controlled Trials to identify economic evaluations published before July 2018. The quality of each selected economic evaluation was assessed by two independent reviewers using the Drummond checklist.

RESULTS

Our systematic review was based on 32 economic evaluations using different methodological approaches, different perspectives and different time horizons. Three-quarters of the economic evaluations are full (n = 24) with a Drummond score ≥ 7, synonymous of "high quality". Among them, 66% reported a strategy that was cost-effective. The most assessed immunotherapeutic agent was nivolumab. In patients with renal cell carcinoma or head and neck cancer, it was less likely to be cost-effective than in patients with melanoma or lung cancer.

CONCLUSIONS

Whether or not these findings will be confirmed remains to be seen when market approval to cover more indications is extended and new effective immunotherapeutic agents become available.

Augmenting Cost-Effectiveness Analysis for Uncertainty: The Implications for Value Assessment-Rationale and Empirical Support

DISCLOSURES

This study received unrestricted funding from the Pharmaceutical Research Manufacturers of America. The authors also do consulting, personally or through their employment, with numerous pharmaceutical manufacturers, payers, and other stakeholders with a general interest in this subject matter.

Nivolumab Versus Docetaxel for Previously Treated Advanced Non-Small Cell Lung Cancer in China: A Cost-Effectiveness Analysis

BACKGROUND AND OBJECTIVE

The economic assessment of immuno-oncology agents in Chinese patients is limited despite a need for new therapies. Nivolumab is the first immune checkpoint inhibitor approved for the second-line treatment of non-small cell lung cancer (NSCLC) in China, and it significantly prolongs overall survival. However, considering the high cost of nivolumab, it is urgent to assess its value in China in terms of both efficacy and cost. The objective of this study was to investigate the cost-effectiveness of nivolumab vs docetaxel in the second-line setting for NSCLC patients from the Chinese healthcare system perspective.

METHODS

A Markov model consisting of three health states, was designed to evaluate the lifetime cost and effectiveness of nivolumab vs docetaxel in the second-line treatment of NSCLC patients. Clinical data was derived from the CheckMate 078 phase III clinical trial, which included 504 patients predominantly from China. Parametric survival models to fit and extrapolate survival data were chosen based on clinical rationality, visual fit and statistical goodness-of-fit. Lifetime costs and health outcomes were calculated, and US$28,899 and $63,564 per quality-adjusted life-year (QALY) were selected as the willingness-to-pay (WTP) threshold values for general regions and affluent regions, respectively. One-way and probabilistic sensitivity analyses were undertaken to explore the robustness of the model. Additional subgroup analyses were performed.

RESULTS

In base case analysis, Nivolumab yielded an additional 0.24 QALYs, at a cost of $93,307 per QALY. Sensitivity analyses suggested that the results to be most sensitive to the price of nivolumab per kg (mean $60.00; range $26.00-$60.00) and the mean patient weight (65 kg, range 52-78 kg). Utility values in progression-free survival state (mean 0.804; range 0.643-0.965) and overall survival hazard ratio (0.68; 97.7% CI 0.52-0.90) had moderate impact on the model results. Subgroup analyses indicated that nivolumab was most cost-effective for patients who were 65 years of age or older ($85,171/QALY), followed by female patients ($85,273/QALY) and patients with tumor PD-L1 expression at least 1% ($90,309/QALY).

CONCLUSIONS

Nivolumab is unlikely to be cost-effective compared with docetaxel for patients with previously treated advanced NSCLC in China. Ensuring that nivolumab is included in the National Reimbursement Drug List (NRDL) may be a valid mean of meeting extensive treatment demands in China.

A Systematic Review of Economic Evaluations Assessing the Cost-Effectiveness of Licensed Drugs Used for Previously Treated Epidermal Growth Factor Receptor (EGFR) and Anaplastic Lymphoma Kinase (ALK) Negative Advanced/Metastatic Non-Small Cell Lung Cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the most commonly diagnosed cancers. There are many published studies of cost-effectiveness analyses of licensed treatments, but no study has compared these studies or their approaches simultaneously.

OBJECTIVE

To investigate the methodology used in published economic analyses of licensed interventions for previously treated advanced/metastatic NSCLC in patients without anaplastic lymphoma kinase or epidermal growth factor receptor expression.

METHODS

A systematic review was performed, including a systematic search of key databases (e.g. MEDLINE, EMBASE, Web of Knowledge, Cost-effectiveness Registry) limited to the period from 01 January 2001 to 26 July 2019. Two reviewers independently screened, extracted data and quality appraised identified studies. The reporting quality of the studies was assessed by using the Consolidated Health Economic Evaluation Reporting Standards and the Philips' checklists.

RESULTS

Thirty-one published records met the inclusion criteria, which corresponded to 30 individual cost-effectiveness analyses. Analytical approaches included partitioned survival models (n = 14), state-transition models (n = 7) and retrospective analyses of new or published data (n = 8). Model structure was generally consistent, with pre-progression, post-progression and death health states used most commonly. Other characteristics varied more widely, including the perspective of analysis, discounting, time horizon, usually to align with the country that the analysis was set in.

CONCLUSIONS

There are a wide range of approaches in the modelling of treatments for advanced NSCLC; however, the model structures are consistent. There is variation in the exploration of sensitivity analyses, with considerable uncertainty remaining in most evaluations. Improved reporting is necessary to ensure transparency in future analyses.

Developing Open-Source Models for the US Health System: Practical Experiences and Challenges to Date with the Open-Source Value Project

The Innovation and Value Initiative started the Open-Source Value Project with the aim to improve the credibility and relevance of model-based value assessment in the context of the US healthcare environment. As a core activity of the Open-Source Value Project, the Innovation and Value Initiative develops and provides access to flexible open-source economic models that are developed iteratively based on public feedback and input. In this article, we describe our experience to date with the development of two currently released, Open-Source Value Project models, one in rheumatoid arthritis and one in epidermal growth factor receptor-positive non-small-cell lung cancer. We developed both Open-Source Value Project models using the statistical programming language R instead of spreadsheet software (i.e., Excel), which allows the models to capture multiple model structures, model sequential treatment with individual patient simulations, and improve integration with formal evidence synthesis. By developing the models in R, we were also able to use version control systems to manage changes to the source code, which is needed for iterative and collaborative model development. Similarly, Open-Source Value Project models are freely available to the public to provide maximum transparency and facilitate collaboration. Development of the rheumatoid arthritis and non-small-cell lung cancer model platforms has presented multiple challenges. The development of multiple components of the model platform tailored to different audiences, including web interfaces, required more resources than a cost-effectiveness analysis for a publication would. Furthermore, we faced methodological hurdles, in particular related to the incorporation of multiple competing model structures and novel elements of value. The iterative development based on public feedback also posed some challenges during the review phase, where methodological experts did not always understand feedback from clinicians and vice versa. Response to the Open-Source Value Project by the modeling community and patient organizations has been positive, but feedback from US decision makers has been limited to date. As we progress with this project, we hope to learn more about the feasibility, benefits, and challenges of an open-source and collaborative approach to model development for value assessment.