1. The incremental cost-effectiveness ratio of the pertuzumab group was $436,679 per QALY gained.
2. Even if pertuzumab were free, it would not be considered cost-effective based on a standard willingness-to-pay threshold of $100,000.
Evidence Rating Level: 2 (Good)
Study Rundown: Pertuzumab (a human epidermal growth factor 2 (HER2) inhibitor) became publicly funded in Ontario, Canada in 2013 for patients with metastatic breast cancer due to its survival benefit. However, previous model-based economic evaluations have suggested it may not be cost-effective. This retrospective study evaluated the cost-effectiveness of pertuzumab using real-world population-based data. Patients with metastatic breast cancer who underwent treatment between January 1, 2008, to March 31, 2018, were identified. Those who received pertuzumab, trastuzumab (another HER2 inhibitor) and chemotherapy after pertuzumab funding constituted the pertuzumab group, while those who received the latter two therapies before pertuzumab funding constituted the control group. Cost-effectiveness was denoted by life-years (LY) and quality-adjusted life-years (QALY). Categories incurring the highest cost in the pertuzumab group were pertuzumab, outpatient cancer treatment delivery, physician claims, and trastuzumab costs. Mean total health care cost was higher in the pertuzumab group, with the costs of outpatient cancer treatment, pertuzumab and trastuzumab being the main contributors to this difference. After reducing the price of pertuzumab to zero, the incremental cost-effectiveness ratio (ICER) of pertuzumab was still higher than the standard willingness-to-pay threshold. Limitations to this study include the possibility of selection bias and a short study period relative to longer model-based estimates. The strength of this study is that it supported previous studies’ conclusions of pertuzumab not being cost-effective. In addition, it puts into question the assessment of publicly funding pertuzumab, which could allow for potential consideration of alternative funding approaches. Overall, while pertuzumab may show a clinical benefit as a treatment adjuvant for metastatic breast cancer patients, it is not considered to be cost-effective at a common willingness-to-pay threshold of $100,000.
In-Depth [retrospective cohort]: This real-world population-based retrospective economic evaluation looked at 1823 patients in Ontario, Canada, with metastatic breast cancer, who received treatment between January 1, 2008, to March 31, 2018. The pertuzumab group comprised of 912 patients who received pertuzumab, trastuzumab and chemotherapy after public funding of pertuzumab, whereas the control group comprised of 911 patients who received trastuzumab and chemotherapy before pertuzumab funding. After propensity score matching, there was a total of 579 pairs. 5-year total cost was 89% higher in the pertuzumab group and the difference between the two groups was $192,139 (95% confidence interval [CI], $160,715 to $224,736; P<0.05). The primary contributors for this difference were the costs of outpatient cancer treatment delivery (24% contribution to total difference), trastuzumab (15%) and pertuzumab (60%). The ICER of pertuzumab was $316,203 per LY gained (95% CI, $247,725 to $498,153; P<0.05) and $436,679 per QALY gained (95% CI, $288,990 to $833,190; P<0.05). Lowering the discount rate from 1.5% to 0% only slightly lowered the ICERs of pertuzumab. Reducing the price of pertuzumab to $0 yielded an ICER of $174,027 / QALY gained, which was still significantly above the standard willingness-to-pay threshold of $100,000. The high ICER amount even after eliminating the cost of pertuzumab can be explained by a longer survival in the pertuzumab group, leading to increased use of trastuzumab and by consequent, increased cost. Only when the cost of both trastuzumab and pertuzumab was reduced to 71% was the ICER less than the standard willingness-to-pay threshold. Overall, pertuzumab had an ICER much higher than the conventional willingness-to-pay threshold of $100,000, even when its price was reduced to $0.
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