OBJECTIVES : This study aimed to evaluate health state utility in previously treated metastatic triple-negative breast cancer (mTNBC) patients.

METHODS : This study examined the EQ-5D-3L data collected from patients enrolled in the KEYNOTE-119 trial, a multicenter, worldwide, randomized Phase III trial comparing pembrolizumab to chemotherapy per physician’s choice (Capecitabine, vinorelbine, gemcitabine or eribulin) for subjects receiving second or third treatment for mTNBC. Two approaches of defining health states are considered in analyzing utility: time-to-death and progression-based health states. Generic health statuses assessed from the EQ-5D-3L questionnaire were converted to population-based utility values using published algorithms.

RESULTS : Data came from 560 patients who had at least one evaluable EQ-5D record. No statistically significant difference in the utility scores between the treatment arms were observed, therefore the utilities from the pooled treatment groups are reported. Mean utility for patients in progression-free and progressive disease state is 0.715 (95% CI 0.701, 0.730) and 0.601 (95% CI 0.571, 0.631), respectively. The decrease of mean utility score on disease progression (0.104) is considered as clinically meaningful. Patients were split into five groups based on their time to death after the EQ-5D questionnaire was taken - over 360 days, 180–360 days, 90–180 days, 30-90 and under 30 days. Mean utility in each time-to-death category is 0.765(95% CI 0.750, 0.779), 0.655 (95% CI 0.624, 0.687), 0.586 (95% CI 0.549, 0.624), 0.517(95% CI 0.471, 0.564), and 0.264(95% CI 0.128, 0.401). The results showed a large decrease in utility by time to death category.

CONCLUSIONS : The results showed that quality of life for metastatic TNBC patients rapidly deteriorates during the end of life period. The deterioration of utility associated with disease progression and time to death is clinically meaningful. The utility values estimated from the study will inform economic evaluations of treatments in metastatic TNBC.