Economic evaluation of letrozole in the treatment of advanced breast cancer in postmenopausal women in Canada

Health Technology Assessment Challenges in Oncology: 20 Years of Value in Health

BACKGROUND

Oncology treatments have changed from chemotherapies to targeted therapies and more recently immuno-oncology. This has posed special challenges in the field of health technology assessment (HTA): capturing quality of life (QOL) associated with toxicity due to chemotherapy, crossover upon progression in targeted therapy trials, and survival extrapolation for immuno-oncology drugs.

OBJECTIVES

To showcase 20 years of Value in Health (ViH) publications in oncology.

METHODS

A review was undertaken of oncology articles published in ViH from May 1998 to August 2018. Full-length articles published in ViH with the keywords "oncology," "cancer," "h(a)ematology," and "malignancy" were included for review. Conference abstracts were excluded.

RESULTS

Four major themes were identified: (1) QOL and the development of multiple functional assessment of cancer therapy tools and mapping instruments; (2) analysis of clinical evidence using indirect comparisons, network analyses, and adjustment for crossovers; (3) modeling, Markov models, partitioned survival models, and extrapolation methods; and (4) financial implications and how to deal with uncertainty, introduction of conditional reimbursement, managed entry, and risk share agreements.

DISCUSSION

This review article highlights the important role ViH has played in disseminating HTA research in oncology. A few key issues loom on the horizon: precision medicine, further development and practical application of new QOL measures, methods for translating clinical evidence, and exploration of modeling techniques. For a better understanding of the complex interplay between access and financial risk management, ViH will no doubt continue to promote pioneering research in HTA and oncology.

Structural Uncertainty of Markov Models for Advanced Breast Cancer

Objective. To examine the impact of structural uncertainty of Markov models in modeling cost-effectiveness for the treatment of advanced breast cancer (ABC). Methods. Four common Markov models for ABC were identified and examined. Markov models 1 and 2 have 4 health states (stable-disease, responding-to-therapy, disease-progressing, and death), and Markov models 3 and 4 only have 3 health states (stable-disease, disease-progressing, and death). In models 1 and 3, the possibility of death can occur in any health state, while in models 2 and 4, the chance of dying can only occur in the disease-progressing health state. A simulation was conducted to examine the impact of using different model structures on cost-effectiveness results in the context of a combination therapy of lapatinib and capecitabine for the treatment of HER2-positive ABC. Model averaging with an assumption of equal weights in all 4 models was used to account for structural uncertainty. Results. Markov model 3 yielded the lowest incremental cost-effectiveness ratio (ICER) of $303,909 per quality-adjusted life year (QALY), while Markov model 1 produced the highest ICER ($495,800/QALY). At a willingness-to-pay threshold of $150,000/QALY, the probabilities that the combination therapy is considered to be cost-effective for Markov models 1, 2, 3, and 4 were 14.5%, 14.1%, 21.6%, and 17.0%, respectively. When using model averaging to synthesize different model structures, the resulting ICER was $389,270/QALY. Conclusions. Our study shows that modeling ABC with different Markov model structures yielded a wide range of cost-effectiveness results, suggesting the need to investigate structural uncertainty in health economic evaluation. When applied in the context of HER2-positive ABC treatment, the combination therapy with lapatinib is not cost-effective, regardless of which model was used and whether uncertainties were accounted for.

An indirect comparison of the efficacy of bevacizumab plus carboplatin and paclitaxel versus pemetrexed with cisplatin in patients with advanced or recurrent non-squamous adenocarcinoma non-small cell lung cancer

OBJECTIVE

There are two new treatment options available for the treatment of adenocarcinoma histology non-small cell lung cancer (NSCLC) which offer improved benefit in terms of progression-free (PFS) and overall survival (OS) over chemotherapy. Both bevacizumab and pemetrexed when combined with chemotherapy significantly increase PFS and OS in patients with advanced NSCLC versus chemotherapy alone. The aim of this analysis was to compare the efficacy for patients with non-squamous adenocarcinoma NSCLC treated with bevacizumab, carboplatin and paclitaxel (BCP) to pemetrexed and cisplatin (PC) by using indirect comparison (ITC) methodology.

EXPERIMENTAL DESIGN

In the absence of head-to-head trials, ITC was performed on patients with adenocarcinoma histology non-squamous NSCLC to compare the relative benefit of first-line therapies BCP vs. PC by hazard ratios (HR). Subsequently, these HRs were used in a decision-analytic Markov model with a lifelong time horizon to extrapolate the long-term effectiveness of the two treatments.

RESULTS

ITC estimated HRs for the primary endpoints in the bevacizumab study E4599 showed that BCP treatment in non-squamous adenocarcinoma NSCLC patients resulted in a BCP HR of 0.82 versus PC. The long-term predictions from the Markov model yielded a mean survival of 1.48 years (95% CI 1.34, 1.62 years) (or 17.7 months) for BCP compared with 1.29 years (95% CI 1.16, 1.42 years) (or 15.4 months) for PC.

CONCLUSIONS

Based on our decision analysis, triplet BCP targeted therapy in patients with advanced non-squamous adenocarcinoma NSCLC compared with doublet PC chemotherapy results in improved expected values for overall long-term survival. Therefore, from the efficacy perspective, bevacizumab in combination with platinum-based chemotherapy can be considered as the targeted therapy of choice for patients with advanced non-squamous adenocarcinoma NSCLC.

Cost Effectiveness of Ixabepilone Plus Capecitabine for Metastatic Breast Cancer Progressing After Anthracycline and Taxane Treatment

Purpose

Using data from a recent randomized trial, we evaluated the cost effectiveness of ixabepilone plus capecitabine versus capecitabine alone in patients with predominantly metastatic breast cancer considered to be taxane-resistant and previously treated with or resistant to an anthracycline.

Methods

We developed a stochastic decision-analytic model to represent data collected in the trial on medical resource use, health-related quality of life, and clinical outcomes. Estimates of overall survival were conditional on level of tumor response. We assigned monthly costs and utility weights according to periods defined by the duration of study treatment, time from discontinuation of the study drug until disease progression, and from progression until death and were specific to the level of response and receipt of subsequent therapy. Medical resources were valued in 2008 US dollars. We performed Monte Carlo simulations and sensitivity analyses to evaluate model uncertainty.

Results

Overall survival was significantly associated with level of tumor response (P < .001). Total costs were estimated at $60,900 for patients receiving ixabepilone plus capecitabine and $30,000 for patients receiving capecitabine alone. The estimated gain in life expectancy with ixabepilone was 1.96 months (95% CI, 1.36 to 2.64 months); the estimated gain in quality-adjusted survival was 1.06 months (95% CI, 0.09 to 2.03 months). The resulting incremental cost-effectiveness ratio was $359,000 per quality-adjusted life-year (95% CI, $183,000 to $4,030,000). In sensitivity analyses, the results were robust to changes in numerous inputs and assumptions.

Conclusion

Addition of ixabepilone to capecitabine adds approximately $31,000 to overall medical costs and affords approximately 1 additional month of quality-adjusted survival.

Review of cost-effectiveness analyses in hormonal therapies in advanced breast cancer

Many new cancer treatments that slow progression and extend survival are emerging. These advances bring new hope to patients and physicians, but often increase health expenditures in an already cost-conscious environment. To help guide resource allocation decisions, cost-effectiveness models are constructed to compare the costs and outcomes of new treatments with current options, and to encourage the uptake of new technologies. This study focuses on the cost-effectiveness studies published since 1997 for hormonal treatment options in advanced breast cancer. This paper: i) examines the quality of studies in terms of reporting methods and transparency of the models; ii) compares the calculated cost-effectiveness ratios; and iii) makes recommendations for future cost-effectiveness models in advanced breast cancer.

Letrozole: a pharmacoeconomic review of its use in postmenopausal women with breast cancer

Letrozole (Femara), an aromatase inhibitor that blocks estrogen synthesis by inhibiting the final step of the estrogen biosynthetic pathway, is approved for use in a wide range of breast cancer settings. Randomised clinical trials in postmenopausal women with hormone-responsive early-stage breast cancer have demonstrated that, as adjuvant therapy, letrozole has greater efficacy than tamoxifen. It is also more effective than placebo as extended adjuvant therapy after completion of tamoxifen therapy in these patients. In women with hormone-responsive advanced breast cancer, letrozole is superior to tamoxifen in prolonging the time to disease progression and time to treatment failure in a first-line setting, and is at least as effective as anastrozole and more effective than megestrol for some endpoints (in one of two trials) in a second-line setting. Letrozole is generally well tolerated, and in a health-related quality-of-life analysis from a large clinical trial, patient well-being with letrozole as extended adjuvant therapy did not differ from that with placebo. Modelled analyses from the UK and the US suggest that, in postmenopausal women with hormone-receptor-positive early-stage breast cancer, letrozole is likely to be a cost-effective alternative to tamoxifen as adjuvant therapy; moreover, using letrozole as extended adjuvant therapy after tamoxifen, rather than no further treatment, is also a cost-effective treatment strategy. Sensitivity analyses have shown these results to be robust. In terms of direct healthcare costs, pharmacoeconomic models suggest that letrozole is a cost-effective alternative to tamoxifen as first-line therapy in postmenopausal women with hormone-responsive advanced breast cancer from the perspectives of the UK NHS, the Canadian and Italian public healthcare systems and the Japanese national health insurance system. Incremental costs per QALY or progression-free year gained over tamoxifen were well within the recommended limits for acceptability of new agents that are more effective and more expensive than existing therapies in the UK, Japan and Canada. Modelled analyses from the UK and Canada have also suggested that letrozole is cost effective as second-line therapy for advanced breast cancer in postmenopausal women who have disease progression following anti-estrogen therapy. In conclusion, letrozole is an effective and well tolerated treatment for postmenopausal women with early-stage or advanced hormone-responsive breast cancer. Pharmacoeconomic analyses from UK and North American perspectives support the use of letrozole in hormone-responsive early-stage breast cancer in both the adjuvant and extended adjuvant settings. In addition, other modelled analyses conducted in a variety of healthcare systems across different countries consistently suggest that letrozole is cost effective in advanced treatment settings.

Aromatase inhibitors in breast cancer: a review of cost considerations and cost effectiveness

Aromatase inhibitors (AIs) have been evaluated clinically in a wide range of breast cancer treatment settings. Although these agents appear to have clinical superiority, they are more expensive than the therapies (primarily tamoxifen) they have been compared with, thus economic evaluation is required to consider their incremental value to the payer. This paper reviews published economic evaluations of AIs as first-line therapy for advanced cancer, and as adjuvant therapy for early breast cancer. The evaluations in the advanced setting demonstrate a range of different modelling techniques and consider the payer's perspective in three healthcare systems. There is broad similarity in the application of standard cohort Markov modelling techniques to evaluate AIs in the early breast cancer setting, covering four separate health system perspectives. AIs appear cost effective compared with current practice. An analysis in the advanced setting suggests that letrozole may be the more cost-effective AI. No direct comparisons of alternative AIs in the adjuvant setting are reported, although indirect comparisons may be feasible. Future evaluations of treatment strategies over the entire course of the disease may also be needed.

A stochastic economic evaluation of letrozole versus tamoxifen as a first-line hormonal therapy: for advanced breast cancer in postmenopausal patients

BACKGROUND

Letrozole is a third-generation aromatase inhibitor that is a feasible alternative to tamoxifen as a first-line hormonal therapy for patients with advanced breast cancer.

OBJECTIVE

This paper presents the results of an economic evaluation comparing letrozole and tamoxifen as first-line hormonal therapies in postmenopausal women diagnosed with advanced breast cancer.

PERSPECTIVE

UK National Health Service.

DESIGN

A decision model (Markov process) was built describing possible patient pathways from the point of diagnosis to death. The model was populated using patient-specific clinical trial data, data from the existing literature, and expert opinion. Stochastic analyses of the model were undertaken, whereby the majority of the input parameters were described as probability distributions to represent the uncertainty about their true value. Costs were presented in year 2000 values.

RESULTS

The baseline results showed that letrozole is a cost-effective alternative to tamoxifen with a mean incremental cost per life-year gained of pound 2342, whilst the incremental cost increases to just over pound 10,000 at the 95th percentile of the cost-effectiveness range (2000 values).

CONCLUSIONS

The results of the economic analysis indicate that letrozole is a cost-effective alternative first-line therapy compared with tamoxifen for postmenopausal women with advanced breast cancer, achieving additional life-years with a modest increase in costs.