OBJECTIVES

: In Canada, the manufacturer submission for public funding of pertuzumab to treat metastatic breast cancer (MBC) estimated an additional 0.642 life years gained (LYG) and an incremental cost-effectiveness ratio (ICER) of $187,376/LYG over 10 years (CADTH-pCODR, 2013). The objective of this retrospective cohort analysis was to examine the comparative real-world population-based effectiveness and cost-effectiveness of adding pertuzumab to trastuzumab-chemotherapy among MBC patients in Ontario, Canada.

METHODS

: MBC patients were identified from the Ontario Cancer Registry and linked to the New Drug Funding Program database to identify receipt of treatment between 1/1/2008 to 3/31/2018. Cases received pertuzumab-trastuzumab-chemotherapy after universal public funding of pertuzumab (Nov 2013); controls received trastuzumab-chemotherapy before pertuzumab funding. Baseline demographic and clinical characteristics (e.g., age, socioeconomic, comorbidities, prior adjuvant therapy) were identified from linked administrative databases and balanced between groups using propensity score matching. Kaplan-Meier methods were used to estimate life-years. 5-year total costs from the public health system perspective were estimated from administrative claims databases. Costs and life-years were adjusted for censoring using inverse probability weighting. ICERs, 95% bootstrapped confidence intervals, and incremental net benefit (INB) were calculated.

RESULTS

: We identified 1,823 MBC patients (912 cases and 911 controls), and matched 579 pairs. Pertuzumab provided an additional 0.63 (CI: 0.48-0.84) LYG at an incremental cost of $196,622 ($180,774-$219,172), with mean ICER of $312,147/LYG ($260,752-$375,492). At a threshold of $100,000/LYG, the INB was -$133,632 (-$151,525, -$115,739) with <1% probability of being cost-effective. Key drivers of incremental cost between groups included drug and cancer clinic costs.

CONCLUSIONS

: The addition of pertuzumab to trastuzumab-chemotherapy for MBC increased survival but at significant costs. The ICER based on direct real-world data was higher than the initial economic model due to higher incremental costs for patients receiving pertuzumab. This study demonstrated feasibility of using real-world data to derive patient-level ICERs to inform life-cycle health technology assessment.