Cost-effectiveness of Voretigene Neparvovec-rzyl vs Standard Care for RPE65-Mediated Inherited Retinal Disease

Cost-of-illness studies of inherited retinal diseases: a systematic review

BACKGROUND

While health care and societal costs are routinely modelled for most diseases, there is a paucity of comprehensive data and cost-of-illness (COI) studies for inherited retinal diseases (IRDs). This lack of data can lead to underfunding or misallocation of resources. A comprehensive understanding of the COI of IRDs would assist governmental and healthcare leaders in determining optimal resource allocation, prioritizing funding for research, treatment, and support services for these patients.

METHODS

Following PRISMA guidelines, a literature search was conducted using Medline, EMBASE and Cochrane databases, from database inception up to 30 Jun 2023, to identify COI studies related to IRD. Original studies in English, primarily including patients with IRDs, and whose main study objective was the estimation of the costs of IRDs and had sufficiently detailed methodology to assess study quality were eligible for inclusion. To enable comparison across countries and studies, all annual costs were standardized to US dollars, adjusted for inflation to reflect their current value and recalculated on a "per patient" basis wherever possible. The review protocol was registered in PROSPERO (registration number CRD42023452986).

RESULTS

A total of nine studies were included in the final stage of systematic review and they consistently demonstrated a significant disease burden associated with IRDs. In Singapore, the mean total cost per patient was roughly US$6926/year. In Japan, the mean total cost per patient was US$20,833/year. In the UK, the mean total cost per patient with IRD ranged from US$21,658 to US$36,549/year. In contrast, in the US, the mean total per-patient costs for IRDs ranged from about US$33,017 to US$186,051 per year. In Canada, these mean total per-patient costs varied between US$16,470 and US$275,045/year. Non-health costs constituted the overwhelming majority of costs as compared to healthcare costs; 87-98% of the total costs were due to non-health costs, which could be attributed to diminished quality of life, poverty, and increased informal caregiving needs for affected individuals.

CONCLUSION

IRDs impose a disproportionate societal burden outside health systems. It is vital for continued funding into IRD research, and governments should incorporate societal costs in the evaluation of cost-effectiveness for forthcoming IRD interventions, including genomic testing and targeted therapies.

Single Center Experience with Voretigene Neparvovec Gene Augmentation Therapy in RPE65 Mutation-Associated Inherited Retinal Degeneration in a Clinical Setting

PURPOSE

To assess the impact of baseline data on psychophysical and morphological outcomes of subretinal voretigene neparvovec (VN) (Luxturna, Spark Therapeutics, Inc.) treatment.

DESIGN

Single-center, retrospective, longitudinal, consecutive case series.

PARTICIPANTS

Patients with RPE65-biallelic mutation-associated inherited retinal degeneration (RPE65-IRD) treated between February 2020 and March 2022 with VN and oral immunosuppression according to the manufacturer's recommendation by one surgeon (F.G.H.).

METHODS

Retrospective analysis of surgical and clinical records, ancillary testing, and retinal imaging after VN therapy for RPE65-IRD. Descriptive statistics compared data at baseline up to 32 months post-treatment.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), low-luminance VA (LLVA), Goldmann visual fields (GVFs), chromatic full-field stimulus threshold (FST) testing (FST), scotopic and photopic 2-color threshold perimetry (2CTP), and multimodal retinal imaging.

RESULTS

Thirty eyes of 19 patients were analyzed (10 pediatric patients < 20 years; 20 adult patients > 20 years of age; overall range: 8-40 years) with a median follow-up of 15 months (range, 1-32). The fovea was completely or partially detached in 16 eyes, attached in 12 eyes, and not assessable in 2 eyes on intraoperative imaging. Median BCVA at baseline was better in the pediatric group (P < 0.05) and did not change significantly independent of age. Meaningful loss of BCVA (≥ 0.3 logarithm of the minimal angle of resolution [logMAR]) occurred in 5 of 18 adult eyes, and a meaningful gain (≥-0.3 logMAR) occurred in 2 of 18 adult and 2 of 8 pediatric eyes. The LLVA and scotopic 2CTP improved considerably in pediatric patients. Scotopic blue FST improved at all ages but more in pediatric patients (8/8 eyes gained ≥ 10 decibels [dB]; P < 0.05). In pediatric patients, median GVF improved by 20% for target V4e and by 50% for target III4e (target I4e not detected). Novel atrophy developed in 13 of 26 eyes at the site of the bleb or peripheral of vascular arcades. Improvements in FST did not correlate with development of chorioretinal atrophy at 12 months. Mean central retinal thickness was 165.87 μm (± 26.26) at baseline (30 eyes) and 157.69 μm (± 30.3) at 12 months (26 eyes). Eight adult patients were treated unilaterally. The untreated eyes did not show meaningful changes during follow-up.

CONCLUSIONS

These data in a clinical setting show the effectiveness of VN therapy with stable median BCVA and mean retinal thickness and improvements of LLVA, FST, and 2CTP up to 32 months. Treatment effects were superior in the pediatric group. We observed new chorioretinal atrophy in 50% of the treated eyes.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

EQ-5D-5L health utility scores in Australian adults with inherited retinal diseases: A cross-sectional survey

PURPOSE

Economic evaluations of interventions for ocular disease require utility scores that accurately represent quality of life in the target population. This study aimed to describe the distribution of EQ-5D-5L utility values among Australian adults with symptomatic inherited retinal diseases (IRDs) and to assess the relationship between these scores and vision-related quality of life.

METHODS

A survey was administered predominantly online in 2021. Participants completed the EQ-5D-5L general health utility instrument, the EQ vertical visual analogue scale (EQ-VAS) and the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25). Self-reported IRD diagnoses were classified as being associated with central or widespread retinal involvement.

RESULTS

Responses from 647 participants aged 18-93 years were included, 50.1% were men and 77.6% had an IRD associated with widespread retinal involvement. The majority reported no problems with self-care and no pain/discomfort but did report anxiety/depression and problems with work, study, housework, or family/leisure activities. Most people with widespread involvement reported problems with mobility. Median EQ-5D-5L utility was 0.88 and 0.91 among people with widespread and central involvement, respectively (age and sex-adjusted p = 0.029); and median EQ-VAS was 75 and 80, respectively (adjusted p = 0.003). A moderate curvilinear correlation was observed between EQ-5D-5L and NEI-VFQ-25 composite score (Spearman's ρ 0.69), but not all people with poor vision-related quality of life had low EQ-5D-5L utility values.

CONCLUSIONS

EQ-5D-5L health utility values are correlated with vision-related quality of life among adults with IRDs. However, the EQ-5D-5L may not be sensitive to the full impact of vision impairment on quality of life.

The economic burden of inherited retinal disease in Singapore: a prevalence-based cost-of-illness study

OBJECTIVE

To assess the economic impact of inherited retinal disease (IRD) among Singaporeans.

METHODS

IRD prevalence was calculated using population-based data. Focused surveys were conducted for sequentially enrolled IRD patients from a tertiary hospital. The IRD cohort was compared to the age- and gender-matched general population. Economic costs were expanded to the national IRD population to estimate productivity and healthcare costs.

RESULTS

National IRD caseload was 5202 cases (95% CI, 1734-11273). IRD patients (n = 95) had similar employment rates to the general population (67.4% vs. 70.7%; p = 0.479). Annual income was lower among IRD patients than the general population (SGD 19,500 vs. 27,161; p < 0.0001). Employed IRD patients had lower median income than the general population (SGD 39,000 vs. 52,650; p < 0.0001). Per capita cost of IRD was SGD 9382, with a national burden of SGD 48.8 million per year. Male gender (beta of SGD 6543, p = 0.003) and earlier onset (beta of SGD 150/year, p = 0.009) predicted productivity loss. Treatment of the most economically impacted 10% of IRD patients with an effective IRD therapy required initial treatment cost of less than SGD 250,000 (USD 188,000) for cost savings to be achieved within 20 years.

CONCLUSIONS

Employment rates among Singaporean IRD patients were the same as the general population, but patient income was significantly lower. Economic losses were driven in part by male patients with early age of onset. Direct healthcare costs contributed relatively little to the financial burden.

A Decade of Health Innovation: The Impact of New Medicines on Patient Health and the Implications for NICE's Size of Benefit Multiplier

OBJECTIVES

This study aimed to estimate the incremental health benefits of pharmaceutical innovations approved between 2011 and 2021 and the share that would surpass the National Institute for Health and Care Excellence (NICE) "size of benefit" decision weight thresholds.

METHODS

We identified all US-approved drugs between 2011 and 2021. Health benefits, in terms of quality-adjusted life-years (QALYs) for each treatment, were extracted from published cost-effectiveness analyses. Summary statistics by therapeutic area and cell/gene therapy status identified the treatments with the largest QALY gains.

RESULTS

The Food and Drug Administration approved 483 new therapies between 2011 and 2021 and of these 252 had a published cost-effectiveness analysis meeting our inclusion criteria. The average incremental health benefits produced by these treatments were 1.04 QALYs (SD = 2.00) relative to standard of care, with wide variation by therapeutic area. Pulmonary and ophthalmologic therapies produced the highest health benefits with 1.47 (SD = 2.17, n = 13) and 1.41 QALYs gained (SD = 3.53, n = 7), respectively; anesthesiology and urology had the lowest gains (< 0.1 QALYs). Cell and gene therapies produced an average health benefit that was 4 times greater than noncell and gene therapies (4.13 vs 0.96). Among the top treatments in terms of incremental QALYs gained, half (10 of 20) were oncology therapies. Three of 252 treatments (1.2%) met NICE's threshold for a "size of benefit" multiplier.

CONCLUSIONS

Treatments for rare disease, oncology, and cell and gene therapies produced some of the highest level of health innovation relative to previous standard of care, but few therapies would have qualified for NICE's "size of benefit" multiplier as currently constructed.

Emerging Gene Therapy Technologies for Retinal Ganglion Cell Neuroprotection

ABSTRACT

Optic neuropathies encompass a breadth of diseases that ultimately result in dysfunction and/or loss of retinal ganglion cells (RGCs). Although visual impairment from optic neuropathies is common, there is a lack of effective clinical treatments. Addressing a critical need for novel interventions, preclinical studies have been generating a growing body of evidence that identify promising new drug-based and cell-based therapies. Gene therapy is another emerging therapeutic field that offers the potential of specifically and robustly increasing long-term RGC survival in optic neuropathies. Gene therapy offers additional benefits of driving improvements following a single treatment administration, and it can be designed to target a variety of pathways that may be involved in individual optic neuropathies or across multiple etiologies. This review explores the history of gene therapy, the fundamentals of its application, and the emerging development of gene therapy technology as it relates to treatment of optic neuropathies.

Analysis of the Gene Therapies Authorized by the United States Food and Drug Administration and the European Medicines Agency

BACKGROUND

Gene therapy, altering the genes inside human cells, has recently emerged as an alternative for preventing and treating disease. Concerns have been expressed about the clinical value and the high cost of gene therapies.

OBJECTIVE

This study assessed the characteristics of the clinical trials, authorizations, and prices of gene therapies in the United States and the European Union.

RESEARCH DESIGN

We collected regulatory information from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) and manufacturer-listed prices from the United States, UK, and Germany. Descriptive statistics and t tests were conducted in the study.

RESULTS

As of January 1, 2022, the FDA and EMA authorized 8 and 10 gene therapies, respectively. The FDA and EMA granted orphan designation to all gene therapies except talimogene laherparepvec. Pivotal clinical trials were nonrandomized, open level, uncontrolled, phase I-III, and included a limited number of patients. Study primary outcomes were mainly surrogate endpoints without demonstration of direct patient benefit. The price of gene therapies at market entry ranged from $200,064 to $2,125,000 million.

CONCLUSIONS

Gene therapy is used to treat incurable diseases that affect only a small number of patients (orphan diseases). Based on this, they are approved by the EMA and FDA with insufficient clinical evidence to ensure safety and efficacy, in addition to the high cost.

Capturing the Impact of Constraints on the Cost-Effectiveness of Cell and Gene Therapies: A Systematic Review

OBJECTIVE

Decision-makers need to resolve constraints on delivering cell and gene therapies to patients as these treatments move into routine care. This study aimed to investigate if, and how, constraints that affect the expected cost and health consequences of cell and gene therapies have been included in published examples of cost-effectiveness analyses (CEAs).

METHOD

A systematic review identified CEAs of cell and gene therapies. Studies were identified from previous systematic reviews and by searching Medline and Embase until 21 January 2022. Constraints described qualitatively were categorised by theme and summarised by a narrative synthesis. Constraints evaluated in quantitative scenario analyses were appraised by whether they changed the decision to recommend treatment.

RESULTS

Thirty-two CEAs of cell (n = 20) and gene therapies (n = 12) were included. Twenty-one studies described constraints qualitatively (70% cell therapy CEAs; 58% gene therapy CEAs). Qualitative constraints were categorised by four themes: single payment models; long-term affordability; delivery by providers; manufacturing capability. Thirteen studies assessed constraints quantitatively (60% cell therapy CEAs; 8% gene therapy CEAs). Two types of constraint were assessed quantitatively across four jurisdictions (USA, Canada, Singapore, The Netherlands): alternatives to single payment models (n = 9 scenario analyses); improving manufacturing (n = 12 scenario analyses). The impact on decision-making was determined by whether the estimated incremental cost-effectiveness ratios crossed a relevant cost-effectiveness threshold for each jurisdiction (outcome-based payment models: n = 25 threshold comparisons made, 28% decisions changed; improving manufacturing: n = 24 threshold comparisons made, 4% decisions changed).

CONCLUSION

The net health impact of constraints is vital evidence to help decision-makers scale up the delivery of cell and gene therapies as patient volume increases and more advanced therapy medicinal products are launched. CEAs will be essential to quantify how constraints affect the cost-effectiveness of care, prioritise constraints to be resolved, and establish the value of strategies to implement cell and gene therapies by accounting for their health opportunity cost.

Challenges for Economic Evaluations of Advanced Therapy Medicinal Products: A Systematic Review

OBJECTIVES

Advanced therapy medicinal products (ATMPs) are drugs for human use for the treatment of chronic, degenerative, or life-threatening diseases that are based on genes, tissues, or cells. This article aimed to identify and critically review published economic analyses of ATMPs.

METHODS

A systematic review of economic analyses of ATMPs was undertaken. Study characteristics, design, sources of data, resources and unit costs, modeling and extrapolation methods, study results, and sensitivity analyses were assessed.

RESULTS

A total of 46 economic analyses of ATMP (from 45 articles) were included; 4 were cell therapy medicinal products, 33 gene therapy medicinal products, and 9 tissue-engineered products. 30 therapies had commercial marketing approval; 39 studies were cost-utility analysis, 5 were cost-effectiveness analysis, and 2 were cost only studies. Four studies predicted that the ATMP offered a step change in the management of the condition and 10 studies estimated that the ATMP would offer a lower mean cost.

CONCLUSIONS

Comparison with historical controls, pooling of data, and use of techniques such as mixture cure fraction models should be used cautiously. Sensitivity analyses should be used across a plausible range of prices. Clinical studies need to be designed to align with health technology assessment requirements, including generic quality of life, and payers should aim for clarity of criteria. Regulators and national payers should aim for compatibility of registers to allow interchange of data. Given the increasing reliance on industry-funded economic analyses, careful critical review is recommended.

Longitudinal analysis of health care costs in patients with childhood onset inherited retinal dystrophies compared to healthy controls

BACKGROUND

We evaluated health care costs in patients with childhood onset visual impairment caused by inherited retinal dystrophies (IRD).

METHODS

The IRD cohort, identified from the Danish Registry of Blind and Partially Sighted Children, was compared to age- and sex-matched controls from the national, Danish population registry. Information on health care expenditures for somatic and psychiatric in- and outpatient services, purchase of prescription medications and paid assistance at home were obtained from national registries for the years 2002-2017.

RESULTS

We included 412 in the IRD cohort (6,290 person years) and 1656 (25,088 person years) in the control cohort. Average, annual health care expenditures from age 0-48 years of age were €1,488 (SD 4,711) in the IRD cohort and €1,030 (4,639) in the control cohort. The largest difference was for out-patient eye care (13.26 times greater, 95% confidence interval 12.90-13.64). Psychiatric in-patient expenditures were 1.71 times greater (95% CI 1.66-1.76) in the IRD cohort but psychiatric out-patient health care costs were comparable between groups.

CONCLUSIONS

Health care costs were approximately 40% greater in the IRD cohort compared to an age- and sex-matched sample from the general Danish population. This is relevant in the current situation with a number of trials aimed at treating IRDs using genetically based therapies. Although eye care expenditures were many times greater, they made up < 10% of the total health care expenditures even in the IRD cohort. The reduced costs related to injuries in the visually impaired cohort was a surprising finding but may reflect a reduced propensity to seek medical care rather than a reduced risk of injuries.

Cost-effectiveness of voretigene neparvovec in the treatment of patients with inherited retinal disease with RPE65 mutation in Switzerland

Objective

We aimed to evaluate the cost-effectiveness of voretigene neparvovec (VN) compared with standard of care (SoC) for patients with inherited retinal disease (IRD) caused by a biallelic RPE65-mutation. VN is a live, non-replicating adeno-associated virus serotype 2 (AAV2). SoC is best supportive care provided to patients with visual impairment. Patients under SoC may experience progressive vision loss leading to complete blindness.

Methods

We adapted a previously published Markov cohort model for IRD. An annual cycle length, life-long time horizon, discount rate of 3% for cost and health outcomes, and Swiss health system perspective were used. Data from a randomised controlled phase III trial of VN versus SoC (ClinicalTrials.gov: NCT00999609) were used to estimate transitions between health states in the first year, after which VN patients were assumed to remain for 39 subsequent years in the health state they were in at the end of the first year. After the 40^th year for VN patients and 1^st year for SoC patients, visual decline was modelled based on observational data on the natural progression of the disease. Quality-adjusted life years (QALYs) were calculated based on an external study which elicited clinicians’ EQ-5D-5L-based utility estimates for IRD patients with a RPE65-mutation. Costs (Swiss Francs (CHF), year 2018-2019) included drug acquisition/ administration, adverse events, testing for sufficient viable retinal cells, and healthcare-related costs of blindness. Societal costs of blindness were added in a complementary analysis. Robustness of the model results were tested in sensitivity and scenario analyses.

Results

For the base-case, VN resulted in incremental costs per patient of CHF 764’402 (VN: CHF 901’654, SoC: CHF 137’252), incremental blindness-free years of 7.67 (VN: 28.32, SoC: 20.65) and incremental QALYs of 6.73 (VN: 18.35, SoC: 11.62), leading to an incremental cost-effectiveness ratio of CHF 113’526 per QALY gained. In probabilistic sensitivity analysis, the cost-effectiveness of VN was better than CHF 100,000 per QALY gained in 41% of iterations. For the scenario analysis in which a societal perspective was adopted and for which a 50% work-related productivity loss from blindness was assumed, incremental costs of CHF 423,837 and an ICER of CHF 62’947 per QALY gained were produced. The scenario assuming VN treatment effect lasts for 20 years produced an ICER of CHF 156’171 per QALY gained, whereas assuming a life-long VN treatment effect resulted in an ICER of CHF 96’384 per QALY gained.

Conclusion

The incremental cost-effectiveness ratio of VN compared to the SoC was estimated to be CHF 113’526 and CHF 62’947 per QALY gained, respectively, from a Swiss healthcare system, and societal perspective assuming a 50% productivity loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08211-y.

Childhood-onset retinal dystrophies reduces life-time income by one third - an individual based socio-economic analysis

BACKGROUND

The aim of this study was to evaluate lifetime income, educational level and workforce participation in patients with childhood-onset inherited retinal dystrophies (IRD).

MATERIAL AND METHODS

The registry-based study using national, Danish databases on education, income, employment and social benefits in a cohort of 515 patients with childhood-onset IRD and without severe systemic comorbidities matched 1:4 to an age- and sex to a control sample of the Danish background population. Socio-economic status was modelled with focus on grade mark points after primary education, highest attained education at 30 years or age, employment and unemployment rate, disability pension and lifetime income.

RESULTS

At 30 years of age, the proportion of those who had primary education as the highest achieved level was higher in the IRD group (35.4% versus 18.7%) and they were more likely to be receiving a disability pension (OR 11.77) or be unemployed (OR 6.63). Those at work had the same number of work hours as the control group, and the same proportion had obtained a Master or PhD degree (14%). At 30 years of age, income earnings were lower in the IRD group and the lifetime income was reduced by 30%.

CONCLUSION

A few among those with childhood-onset IRD were able to obtain high educational levels, and many were assigned a disability pension from early adulthood or were unemployed, resulting in a markedly reduced lifetime income although grade mark points from primary education were comparable, suggesting that the difference was not explained by intellectual differences between the groups.

Critical Reflections on Reimbursement and Access of Advanced Therapies

Background: The health economic literature has questioned the cost-effectiveness and affordability of advanced therapies, proposed adjustments to value assessment frameworks, and discussed the use of outcome-based managed entry agreements and staggered payments in the last few years. The aim of this manuscript is to conduct a critical reflection on assessment criteria and access conditions for reimbursement of advanced therapies.

Methods: A narrative review of the peer-reviewed literature and grey literature was conducted in April 2021 by searching PubMed; Google Scholar; policy and legislative documents; websites of health technology assessment agencies, advanced therapy organisations, governmental advanced therapy innovation programmes, consultancy agencies; ISPOR conference abstracts and presentations.

Results: Based on the available evidence, this manuscript argues that: a) advanced therapies can be cost-effective at high prices set by manufacturers; b) the economic evaluation framework adopted by many payers under-values these products; c) advanced therapies can be affordable and may not require spread payments; d) outcome-based managed entry agreements are theoretically attractive, but challenging in practice; e) the cost-effectiveness of advanced therapies depends on the outcome-based managed entry agreement and payment approach; f) there is a role for multinational collaborations to manage reimbursement and access of advanced therapies.

Conclusions: This manuscript shows that there is no single approach to reimbursement and access of advanced therapies. Instead, we support a more tailored assessment of health economic aspects of advanced therapies, which considers the heterogeneity of these products and their target populations.

The first gene therapy for RPE65 biallelic dystrophy with voretigene neparvovec-rzyl in Brazil

PURPOSE

To report the first Brazilian patient with RPE65 deficiency-inherited retinal dystrophy (RPE65-IRD) treated with voretigene neparvovec-rzyl (VN).

METHODS

An adult patient with Leber congenital amaurosis-2 with a homozygous mutation in the RPE65 gene (p.Phe83Leu) was treated bilaterally with VN. The clinical and surgical aspects are described. The baseline and 4-month postoperative ophthalmologic examinations included measurement of the best-corrected visual acuity (BCVA), full-field stimulus threshold (FST) test, Octopus 900 semiautomated kinetic visual fields (VFs), and microperimetry.

RESULTS

No complications developed in this patient. The BCVA remained stable. The full-field stimulus threshold test (FST) and VFs showed clinically significant improvements bilaterally. The patient reported significant improvements in the ability to perform daily activities, mainly for those requiring the VFs and vision in a low-luminescence environment.

CONCLUSIONS

The treatments were beneficial for this patient who was homozygous for RPE65 p.Phe83Leu. The first VN treatments in an adult Brazilian patient in clinical practice showed measurable improvements in visual outcomes that were meaningful for the patient's daily activities.

TRANSLATIONAL RELEVANCE

This case reinforces the clinical trial results and proves that the procedure is feasible in countries such as Brazil.

Challenges of Cost-Effectiveness Analyses of Novel Therapeutics for Inherited Retinal Diseases

PURPOSE

To investigate the challenges and potential improvement strategies of cost-effectiveness analyses performed for therapeutics targeting inherited retinal diseases (IRDs).

DESIGN

Perspective.

METHODS

A literature review was conducted with discussion of current limitations and improvement recommendations.

RESULTS

Cost-effectiveness analysis (CEA) performed for IRD therapeutics has multiple limitations. First, the available methods used to measure health-related quality of life and health utilities can be inaccurate when used in IRDs. Second, the financial burden to patients and society from vision impairment associated with IRDs has been inadequately studied and includes a variety of expenditures ranging from direct costs of IRD specialty health care to indirect expenses associated with daily living activities. Third, our collective understanding is limited in the areas of IRD natural history and health benefits gained from new IRD treatments (eg, gene therapies). In addition, the therapeutic effect from a patient perspective and its duration of action are not fully understood. Due to the scarcity of data, CEA for newly approved therapies has relied on assumptions and creations of predictive models for both costs and health benefits for these new therapeutics in order to calculate the incremental cost-effectiveness ratio.

CONCLUSIONS

CEA studies performed for IRD therapeutics have been limited by the established health utilities in ophthalmology and the lack of disease-specific information. The assumptions and extrapolations in these studies create substantial uncertainty in incremental cost-effectiveness ratio results. An improved framework is required for CEA of IRD therapeutics in order to determine the cost-effectiveness of each therapy brought from clinical trials to clinical practice.

Challenges in the market access of regenerative medicines, and implications for manufacturers and decision-makers: a systematic review

Aim: Regenerative medicines (RMs) are expected to transform the treatment paradigm of rare, life-threatening diseases, while substantial challenges impede its market access. This study aimed to present these challenges. Materials & methods: Publications identified in the Medline and Embase databases until December 2020 were included. Results: Uncertainties around the relative effectiveness and long-term benefits of RMs are most scrutinized. A new reference case for RMs is questionable, but examining impacts of study perspective, time horizon, discount rate and extrapolation methods on estimates is advised. Establishing reasonable prices of RMs requires increased transparency in the development costs and better values measurements. Outcome-based payments require considerable investments and potential legislative adjustments. Conclusion: Greater flexibility for health technology assessment and economic analyses of RMs is necessary. This comprehensive review may prompt more multi-stakeholder conversations to discuss the optimized strategy for value assessment, pricing and payment in order to accelerate the market access of RMs.

Economic Evidence on Potentially Curative Gene Therapy Products: A Systematic Literature Review

OBJECTIVE

The aim of this review was to summarize all available evidence on the cost effectiveness of potentially curative gene therapies and identify challenges that economic evaluations face in this area.

METHODS

We conducted a systematic review of four databases (PubMed/MEDLINE, Embase, CINAHL, EconLit) and grey literature sources. We conducted the search on August 23, 2019 and updated it on November 26, 2020. We included all English, French and Spanish language studies that addressed a gene therapy that had received regulatory approval or had entered a phase III trial, and also reported on costs related to the therapy. Critical appraisal was conducted to assess quality of reporting in included studies.

RESULTS

Fifty-six studies were identified. Of the 42 full economic evaluations, 71% (n = 30) evaluated chimeric antigen receptor T-cell therapies, most used either a Markov model (n = 17, 40%) and/or a partitioned survival model (n = 17, 40%), and 76% (n = 32) adopted a public or private payer perspective. The model characteristics with the greatest impact on cost effectiveness included assumptions about the efficacy of the treatment and the comparators used.

CONCLUSION

All gene therapies in this review were shown to be more effective than their comparators, although due to high costs not all were considered cost effective at standard cost-effectiveness thresholds. Despite their high cost, some gene therapies have the potential to dominate the alternatives in conditions with high mortality/disability. The choice of comparator and assumptions regarding long-term effectiveness had substantial impacts on cost-effectiveness estimates and need to be carefully considered. Both the quality of inputs and the quality of reporting were highly variable.

Considering potential solutions for limitations and challenges in the health economic evaluation of gene therapies

INTRODUCTION

The limited evidence in the clinical trials of gene therapies (GTs) posed substantial challenges for a reliable health technology assessment (HTA). This paper provides insights into the relationship between the background of diseases and the health economics assessment of GTs.Areas covered: The impacts of differentiated severity and unmet needs of genetic diseases, on the economic analysis of GTs, were discussed.Expert opinion: GTs offer a potential cure or significant clinical improvement, while limitations in clinical evidence constitute major obstacles for a robust assessment of clinical effectiveness and economic outcomes. This uncertainty may be balanced by the severity of the targeted condition and the associated unmet needs, thus leading to a relatively higher acceptance for GTs. Overtime, HTA agencies will become more demanding on comprehensive evidence of long-term effectiveness. With a growing number of GTs on the horizon, to what extent the unmet needs of previously devastating diseases will be fulfilled remain unclear. Nonetheless, comparative studies, either with a historical control group or existing treatments, will be necessary to demonstrate the additional benefits associated with GTs.

Voretigene Neparvovec: A Review in RPE65 Mutation-Associated Inherited Retinal Dystrophy

Voretigene neparvovec (Luxturna^®), a recombinant adeno-associated virus vector-based gene therapy, delivers a functioning copy of the human retinal pigment epithelium-specific 65 kDa (RPE65) gene into retinal cells of patients with reduced or absent levels of RPE65 protein, providing the potential to restore the visual cycle. A single-dose subretinal injection of voretigene neparvovec administered in each eye is approved in several countries worldwide for the treatment of vision loss in adult and paediatric patients with confirmed biallelic RPE65 mutation-associated inherited retinal dystrophy (IRD) and with sufficient viable retinal cells. In the pivotal phase III trial, significant improvements from baseline were seen in the mean bilateral multi-luminance mobility test scores in the voretigene neparvovec group compared with the control group at 1 year. The beneficial effects of voretigene neparvovec treatment were maintained after up to 4 years of follow-up (with follow-up continuing for 15 years). Control recipients were eligible to receive voretigene neparvovec at 1 year, and showed improvements at subsequent follow-ups (≤ 3 years post injection) consistent with those in patients who received voretigene neparvovec at baseline. Most adverse reactions in voretigene neparvovec recipients were transient, asymptomatic and non-serious, and resolved without sequelae (may have been related to voretigene neparvovec, the subretinal injection procedure, concomitant corticosteroid use or a combination thereof). Retinal detachment occurred in one patient at year 4. Although ongoing additional long-term efficacy and safety data are required, voretigene neparvovec is an important novel gene therapy for patients with RPE65 mutation-associated IRD and sufficient viable retinal cells.

The Cost-effectiveness of Gene Therapy for Severe Hemophilia B: Microsimulation Study from the United States Perspective

Adeno-associated virus (AAV)-mediated gene therapy is a novel treatment promising to reduce morbidity associated with hemophilia. While multiple clinical trials continue to evaluate efficacy and safety, limited cost-effectiveness data have been published. This study compared the potential cost-effectiveness of AAV-mediated factor IX(FIX)-Padua gene therapy for severe hemophilia B patients in the United States (US) to on-demand FIX replacement and primary FIX prophylaxis, using either standard or extended half-life FIX products. A microsimulation Markov model was constructed and transition probabilities between health states and utilities were informed by published data. Costs were aggregated using a micro-costing approach. An 18-years-old till death time-horizon from the perspective of a third-party payer in the US was conducted. Gene therapy was more cost-effective than both alternatives considering a $150,000/QALY threshold. The price for gene therapy was assumed $2,000,000 in the base-case scenario, yet one of the one-way sensitivity analyses was conducted using observed manufacturing, administration and five-year follow-up cost of $87,198 for AAV-mediated gene therapy vector as derived from the manufacturing facility and clinical practice at St. Jude Children's Research Hospital. One-way sensitivity analyses showed 10/102 scenarios in which gene therapy was not cost-effective compared to alternative treatments. Notably, gene therapy remained cost-effective in a hypothetical scenario in which we estimated that the discounted factor concentrate price was 20% of the wholesale acquisition cost in the US. Probabilistic sensitivity analysis estimated gene therapy cost-effective at 92% of simulations considering $150,000/QALY threshold. In conclusion, based on detailed simulation inputs and assumptions, gene therapy was more cost-effective than on-demand treatment and prophylaxis for patients with severe hemophilia B.

Methodological Challenges in the Economic Evaluation of a Gene Therapy for RPE65-Mediated Inherited Retinal Disease: The Value of Vision

The emergence of gene therapies challenge health economists to evaluate interventions that are often provided to a small patient population with a specific gene mutation in a single dose with high upfront costs and uncertain long-term benefits. The objective of this study was to illustrate the methodological challenges of evaluating gene therapies and their implications by discussing four economic evaluations of voretigene neparvovec (VN) for the treatment of RPE65-mediated inherited retinal disease. The checklist for economic evaluations of gene therapies of Drummond et al. was applied to the economic evaluations of VN performed by US Institute for Clinical and Economic Review, two country adaptations of the company model in the UK and the Netherlands, and another US publication. The main differences in methodological choices and their impact on cost-effectiveness results were assessed and further explored with sensitivity analyses using the Dutch model. To enable comparison between the economic evaluations, costs were converted to US dollars. Different methodological choices were made in the economic evaluations of VN resulting in large differences in the incremental cost-effectiveness ratio varying from US$79,618 to US$643,813 per QALY. The chosen duration of treatment effect, source of utility values, discount rate and model structure had the largest impact on the cost-effectiveness. This study underlines the findings from Drummond et al. that standard methods can be used to evaluate gene therapies. However, given uncertainty about (particularly long-term) outcomes of gene therapies, guidance is required on the acceptable extrapolation of treatment effect of gene therapies and on how to handle the uncertainty around this extrapolation in scenario and sensitivity analyses to aid health technology assessment research and align submissions of future gene therapies.

Gene therapy for inherited retinal diseases: progress and possibilities

Inherited retinal diseases (IRDs) comprise a heterogeneous group of genetic disorders affecting the retina. Caused by mutations in over 300 genes, IRDs result in visual impairment due to dysfunction and degeneration of photoreceptors, retinal pigment epithelium, or the choroid. Important photoreceptor IRDs include retinitis pigmentosa and Leber congenital amaurosis. Macular dystrophies include Stargardt and Best disease. Currently, IRDs are largely incurable but the landscape of treatment options is rapidly changing for these diseases which, untreated, result in severe visual impairment and blindness.Advances in DNA delivery to the retina and improved genetic diagnosis of IRDs have led to a new era of research into gene therapy for these vision-threatening disorders. Gene therapy is a compelling approach due to the monogenic nature of most IRDs, with the retina being a favourable target for administering genetic vectors due to its immunoprivileged environment, direct visibility, and multiple methods to assess sensitivity and function. Generally, retinal gene therapy involves a subretinal or intravitreal injection of a viral vector, which infects target cells to deliver a therapeutic gene, or transgene. A gene augmentation strategy introduces a functioning copy of a gene to restore expression of a mutated gene, whereas a gene-editing strategy aims to directly edit and correct the mutation. Common delivery vectors include adeno-associated virus (AAV) and lentivirus.Voretigene neparvovec-rzyl (Luxturna) became the first FDA-approved direct gene therapy in December 2017, and the Australian TGA followed suit in August 2020. More are projected to follow, with clinical trials underway for many other IRDs.This review provides an overview of gene therapy for IRDs, including current progress and challenges. A companion article in this issue details target patient populations for IRD gene therapy, and how optometrists can assist in assessing individuals who may be eligible for current and future therapies.

Gene editing technology: Towards precision medicine in inherited retinal diseases

Purpose: To review preclinical and clinical advances in gene therapy, with a focus on gene editing technologies, and application to inherited retinal disease.Methods: A narrative overview of the literature, summarizing the state-of-the-art in clinical gene therapy for inherited retinal disease, as well as the science and application of new gene editing technology.Results: The last three years has seen the first FDA approval of an in vivo gene replacement therapy for a hereditary blinding eye disease and, recently, the first clinical application of an in vivo gene editing technique. Limitations and challenges in this evolving field are highlighted, as well as new technologies developed to address the multitude of molecular mechanisms of disease.Conclusion: Genetic therapy for the treatment of inherited retinal disease is a rapidly expanding area of ophthalmology. New technologies have revolutionized the field of genome engineering and rekindled an interest in precision medicines for these conditions.

Current Management of Inherited Retinal Degeneration Patients in Europe: Results of a Multinational Survey by the European Vision Institute Clinical Research Network

PURPOSE

An increasing number of gene therapies are developed for Inherited Retinal Degenerations (IRD). To date, 1 treatment has been approved for clinical use (FDA USA 2017, EMA Europe 2018, MoHAP UAE 2019, SFDA Saudi Arabia 2019, Swiss Medic Switzerland 2020, TGA Australia 2020, and BFR Brazil 2020). While such therapies do not provide complete cure, they may halt degeneration or partially restore function. Identification of well-characterized patients is an emerging need. We conducted the first multinational survey to understand the management of IRDs in Europe.

METHODS

An electronic survey questionnaire containing 112 questions was developed and sent to the 101 EVICR.net clinical centers (14 European countries and Israel).

RESULTS

The overall response rate was 49%. Only 14% of responding centers do not see IRD patients; 52% that manage IRD patients follow ≥200 patients, 16% > 1,000. Databases exist in 86% of the centers; of these, 75% are local files, 28% local Web-based database, and 19% national Web-based. IRD patients are referred to EVICR.net centers mainly by general ophthalmologists, patient self-referrals, and medical retina specialists. Most IRD patients are first seen in adulthood. Most prominent signs and symptoms depend on the age of onset, for example, nystagmus in infancy, or night blindness, and reduced visual acuity at older age. The time from inquiring for first appointment and clinical diagnosis varies among countries: in 29% of centers, the mean time is <4 weeks, although can be up to 35 months in others. The time to genetic diagnosis is ≥4 weeks, the maximum 10 years, likely depending on access to genetic testing, and the improvement of the tests available. Comprehensive eye examination always includes autofluorescence imaging and perimetry (86% static, 76% kinetic, and 21% microperimetry), and frequently optical coherence tomography (OCT) (95%), electroretinography (93%), and fundus photography (93%). Identified genotypes were reported in 40-80% patients by 69% of centers, and in 80-100% by 5%. Genetic testing is provided by public health insurance in 77% of centers, private health insurance in 38%, center budget in 13%, research funds in 18%; and 15% of centers do not have access to genetic testing.

CONCLUSION

At the start of this era of ocular gene therapy for IRD patients, this first international survey on management of IRDs in Europe highlights significant heterogeneity between centers and across countries and provides important baseline data for researchers, clinicians, pharmaceutical companies, and investors.

Market access of gene therapies across Europe, USA, and Canada: challenges, trends, and solutions

This review can inform gene therapy developers on challenges that can be encountered when seeking market access. Moreover, it provides an overview of trends among challenges and potential solutions.

Voretigene Neparvovec in Retinal Diseases: A Review of the Current Clinical Evidence

Subretinal gene therapy trials began with the discovery of RPE65 variants and their association with Leber congenital amaurosis. The RPE65 protein is critical for the normal functioning of the visual phototransduction cascade. RPE65 gene knockout animal models were developed and showed similar diseased phenotypes to their human counterparts. Proof of concept studies were carried out in these animal models using subretinal RPE65 gene replacement therapy, resulting in improvements in various visual function markers including electroretinograms, pupillary light responses, and object avoidance behaviors. Positive results in animal models led to Phase 1 human studies using adeno-associated viral vectors. Results in these initial human studies also showed positive impact on visual function and acceptable safety. A landmark Phase 3 study was then conducted by Spark Therapeutics using a dose of 1.5 x10¹¹ vector genomes after dose-escalation studies confirmed its efficacy and safety. Multi-luminance mobility testing was used to measure the primary efficacy endpoint due to its excellent reliability in detecting the progression of inherited retinal diseases. After the study met its primary endpoint, the Food and Drug Administration approved voretigene neparvovec (Luxturna^®) for use in RPE65-associated inherited retinal diseases.

Health economic evaluation of gene replacement therapies: methodological issues and recommendations

Objective: To provide recommendations for addressing previously identified key challenges in health economic evaluations of Gene Replacement Therapies (GRTs), including: 1) the assessment of clinical effectiveness; 2) the valuation of health outcomes; 3) the time horizon and extrapolation of effects beyond trial duration; 4) the estimation of costs; 5) the selection of appropriate discount rates; 6) the incorporation of broader elements of value; and 7) affordability. Methods: A literature review on economic evaluations of GRT was performed. Interviews were conducted with 8 European and US health economic experts with experience in evaluations of GRT. Targeted literature reviews were conducted to investigate further potential solutions to specific challenges. Recommendations: Experts agreed on factors to be considered to ensure the acceptability of historical cohorts by HTA bodies. Existing prospective registries or, if not available, retrospective registries, may be used to analyse different disease trajectories and inform extrapolations. The importance of expert opinion due to limited data was acknowledged. Expert opinion should be obtained using structured elicitation techniques. Broader elements of value, beyond health gains directly related to treatment, can be considered through the application of a factor to inflate the quality-adjusted life years (QALYs) or a higher cost-effectiveness threshold. Additionally, the use of cost-benefit analysis and saved young life equivalents (SAVE) were proposed as alternatives to QALYs for the valuations of outcomes of GRT as they can incorporate broader elements of value and avoid problems of eliciting utilities for paediatric diseases. Conclusions: While some of the limitations of economic evaluations of GRT are inherent to limited clinical data and lack of experience with these treatments, others may be addressed by methodological research to be conducted by health economists.

A Review of Methodological Considerations for Economic Evaluations of Gene Therapies and Their Application in Literature

OBJECTIVES

To identify methodological considerations discussed in literature addressing economic evaluations (EEs) of gene therapies (GTs). Additionally, we assessed if these considerations are applied in published GT EEs to increase understanding and explore impact.

METHODS

First a peer-reviewed literature review was performed to identify research addressing methodological considerations of GT EEs until August 2019. Identified considerations were grouped in themes using thematic content analysis. A second literature search was conducted in which we identified published evaluations. The EE quality of reporting was assessed using Consolidated Health Economic Evaluation Reporting Standards.

RESULTS

The first literature search yielded 13 articles discussing methodological considerations. The second search provided 12 EEs. Considerations identified were payment models, definition of perspectives, addressing uncertainty, data extrapolation, discount rates, novel value elements, and use of indirect and surrogate endpoints. All EEs scored satisfactory to good according to Consolidated Health Economic Evaluation Reporting Standards. Regarding methodological application, we found 1 methodological element (payment models) was applied in 2 base cases. Scenarios explored alternative perspectives, survival assumptions, and extrapolation methods in 10 EEs.

CONCLUSIONS

Although EE quality of reporting was considered good, their informativeness for health technology assessment and decision makers seemed limited owing to many uncertainties. We suggest accepted EE methods can broadly be applied to GTs, but few elements may need adjustment. Further research and multi-stakeholder consensus is needed to determine appropriateness and application of individual methodological considerations. For now, we recommend including scenario analyses to explore impact of methodological choices and (clinical) uncertainties. This study contributes to better understanding of perceived appropriate evaluation of GTs and informs best modeling practices.

Value of Anti-Vascular Endothelial Growth Factor Gene Therapy for Neovascular Age-Related Macular Degeneration

PURPOSE

To use discounted cash flow (DCF) analysis to estimate the value creation associated with anti-vascular endothelial growth factor (VEGF) genetic therapy for neovascular age-related macular degeneration (nAMD).

DESIGN

Economic analysis.

PARTICIPANTS

Adults undergoing serial intravitreal anti-VEGF injections in 1 eye for nAMD.

METHODS

Discounted cash flow modeling with scenario analysis was used to derive a present value for a 1-time alternative treatment to lifelong anti-VEGF treatment for nAMD. Multiple sensitivity analyses were performed on the basis of patient age at time of first injection and frequency interval of intravitreal injection.

MAIN OUTCOME MEASURES

Present values of DCF and scenario analyses.

RESULTS

Discounted cash flow analysis of intravitreal anti-VEGF treatment for nAMD resulted in a base-case valuation of $208 420.61, $219 093.31, and $17 379.41 for a 1-time alternative treatment to aflibercept, ranibizumab, and bevacizumab, respectively. This figure covaried significantly with anti-VEGF agent according to the patient age at first injection ($78 323.19-$292 449.87) and frequency of injections ($148 422.91-$388 096.81). In addition, for bevacizumab, variability was driven by the hypothetical degree of clinical superiority of 1-time therapy to repeated intravitreal injections due to reduction in adverse events ($17 379.41-$18 250.79) or reduction in direct or indirect costs associated with age-related macular degeneration ($17 379.41-$657 406.55).

CONCLUSIONS

Anti-VEGF gene therapy approaches can create significantly different value propositions based on the agent modeled, patient age at first injection, frequency of injections, and clinical profile of the medication. Although the use of aflibercept or ranibizumab as a comparative cost metric is logical from a bioequivalence perspective, the disparity in medication costs should not be the primary value driver in applied models. Instead, bevacizumab should be the base case ($17 379.41), with additional value driven from an improvement in quality of life through clinical superiority. A reduction in direct and indirect costs can be used to approximate the value from maintained visual acuity, which is elaborated in the DCF analysis approach described in this article. This model can serve as a basis for assessing the price ceiling of myriad gene therapy approaches. Given the high present values for these therapeutics, innovative costing and reimbursement mechanisms should be further explored, with contingencies for sustained efficacy.

Cost Effectiveness of Voretigene Neparvovec for RPE65-Mediated Inherited Retinal Degeneration in Germany

Purpose

Voretigene Neparvovec-rzyl (VN) is the first available treatment for biallelic RPE65 mutation-associated inherited retinal degeneration, which is usually associated with infancy-onset severe visual impairment and complete blindness during the third life decade. We aim to estimate the cost effectiveness of VN in Germany considering medication costs of €410,550 per eye and potential indirect cost offsets by higher labor force participation.

Methods

We developed an individual patient sampling model to simulate patients over their lifetime. In a Monte Carlo analysis, 1000 simulations are performed. Cycle length of the two-state Markov model is 1 year. For each cycle, visual field and best-corrected visual acuity are tracked, compared with natural progression and converted to quality of life. Direct and indirect costs are recorded and the incremental cost-utility ratio is calculated.

Results

In the base case scenario, VN provides 4.82 additional quality-adjusted life-years over a patient's lifetime at an incremental cost-utility ratio of €156,853 per additional quality-adjusted life-year gained. Sensitivity analyses show the robustness of the results when altering treatment effect duration, discounting of quality-adjusted life-years and costs, direct costs, and natural progression.

Conclusions

Under a lifetime perspective, VN proves to be cost effective for the German statutory health insurance system despite high initial treatment costs. Because VN has important implications for future gene therapies, cost-utility analyses have high economic relevance from a societal perspective.

Translational Relevance

Our research analyzes the value of a gene augmentation therapy in clinical care in terms of quality of life gains for patients with blindness from retinal degeneration.

Progress in treating inherited retinal diseases: Early subretinal gene therapy clinical trials and candidates for future initiatives

Due to improved phenotyping and genetic characterization, the field of 'incurable' and 'blinding' inherited retinal diseases (IRDs) has moved substantially forward. Decades of ascertainment of IRD patient data from Philadelphia and Toronto centers illustrate the progress from Mendelian genetic types to molecular diagnoses. Molecular genetics have been used not only to clarify diagnoses and to direct counseling but also to enable the first clinical trials of gene-based treatment in these diseases. An overview of the recent reports of gene augmentation clinical trials by subretinal injections is used to reflect on the reasons why there has been limited success in this early venture into therapy. These first-in human experiences have taught that there is a need for advancing the techniques of delivery of the gene products - not only for refining further subretinal trials, but also for evaluating intravitreal delivery. Candidate IRDs for intravitreal gene delivery are then suggested to illustrate some of the disorders that may be amenable to improvement of remaining central vision with the least photoreceptor trauma. A more detailed understanding of the human IRDs to be considered for therapy and the calculated potential for efficacy should be among the routine prerequisites for initiating a clinical trial.

An Economic Evaluation of Voretigene Neparvovec for the Treatment of Biallelic RPE65-Mediated Inherited Retinal Dystrophies in the UK

INTRODUCTION

Voretigene neparvovec (VN) is a gene therapy and the first approved pharmacological treatment for biallelic RPE65-mediated inherited retinal dystrophies (IRD), a rare condition that starts in early life and causes vision to progressively deteriorate towards complete blindness. In a phase III trial, treatment with VN significantly improved functional vision and visual function, and in October 2019 the National Institute for Health and Care Excellence (NICE) Highly Specialised Technologies (HST) process recommended VN for patients in England and Wales. We assessed the cost-effectiveness of VN compared with best supportive care (BSC) in individuals with biallelic RPE65-mediated IRD in the UK.

METHODS

A Markov model was developed to estimate the incremental cost per quality-adjusted life-year (QALY) gained for VN compared with BSC, from the perspective of the UK National Health Service and Personal Social Services. Phase III trial data were used to inform transition probabilities up to year 1, after which the treatment effect was assumed to be maintained for 40 years, followed by a decline in vision. A bespoke elicitation exercise involving clinical experts, patients and carers was conducted to estimate utility values for each model health state.

RESULTS

At list price, VN is associated with incremental costs of £612,404 and incremental QALYs of 6.4, resulting in an incremental cost-effectiveness ratio (ICER) of £95,072 per QALY gained. Voretigene neparvovec is associated with a significant undiscounted QALY gain (20.5) and is therefore eligible for additional QALY weighting under the NICE HST process; an ICER of up to £205,000 per QALY gained could be considered cost-effective under this framework.

CONCLUSION

The results of the model show VN to be a cost-effective use of healthcare resources in the UK at list price. The availability of a commercial discount in the UK (as considered in the NICE appraisal) means that in reality the ICER will be even lower. Plain language summary available for this article.