Cost-effectiveness of combined atezolizumab/nab-paclitaxel for advanced triple-negative breast cancer.

e19388 Background: The IMpassion 130 trial found prolonged progression-free and overall survival among PD-L1-positive, advanced triple-negative breast cancer (TNBC) patients receiving atezolizumab and nab-paclitaxel versus nab-paclitaxel alone. These results were the basis of the first FDA approval of a breast cancer immunotherapeutic agent. With the high cost of combined therapy we present a cost-effectiveness analysis of the addition of atezolizumab to nab-paclitaxel for the treatment of advanced TNBC in PD-L1-positive patients. Methods: We constructed a Markov model to simulate cancer progression, survival, and toxicity in advanced TNBC patients receiving atezolizumab and nab-paclitaxel compared to nab-paclitaxel alone. Transition probabilities were derived from the IMpassion 130 trial, while costs (in 2019 US dollars) and health utilities were estimated from the literature. Cost effectiveness was assessed with incremental cost-effectiveness ratios (ICERs), expressed as dollar per quality-adjusted life-year (QALY), with values of less than $100,000/QALY considered cost effective. We conducted one-way and probabilistic sensitivity analyses to examine model uncertainty. Results: Our base-case model found that treatment with atezolizumab and nab-paclitaxel increased overall cost by $120,800 and improved effectiveness by 0.11 QALYs compared with nab-paclitaxel alone, leading to an ICER of $1,101,000/QALY. The base-case model was not sensitive to any single variable. Women in the combined atezolizumab and nab-paclitaxel arm spent more time with stable disease before progression and with progressive disease before death compared to those treated with nab-paclitaxel alone. In our base-case analysis the addition of atezolizumab was not cost effective at any price of atezolizumab secondary to the high costs of stable and progressive disease. If we assumed lower costs of stable disease and progression, our model became sensitive to the cost of atezolizumab. A probabilistic sensitivity analysis found that adding atezolizumab would be cost ineffective 99.9% of the time at a willingness-to-pay of $100,000/QALY. Conclusions: Despite improved clinical outcomes, the addition of atezolizumab would not be considered cost effective in part due to the high costs of stable disease and disease progression among women with advanced TNBC. Novel therapeutics in this costly patient cohort will need to bend the cost curve of stable and progressive disease before becoming cost effective at thresholds acceptable by today’s standards.