Treatment-Free Interval as a Prognostic Factor for Survival Outcomes in Patients with Advanced or Recurrent Endometrial Cancer Treated with Pembrolizumab Plus Lenvatinib: A Multi-Institutional Real-World Cohort Study

Abstract

Simple Summary Endometrial cancer that returns or spreads after first-line chemotherapy is difficult to treat. The combination of pembrolizumab (an immunotherapy) and lenvatinib (a targeted therapy) is a standard second-line option, but clinicians have few tools for estimating the prognosis of individual patients. Using de-identified electronic health records from 122 healthcare organizations in the United States and Europe, we compared propensity score-matched patients who started pembrolizumab plus lenvatinib within 6 months of their last dose of carboplatin plus paclitaxel with those who started it 6 months or later. This treatment-free interval is measured from the last chemotherapy dose to the start of the next treatment, not from the date the cancer was found to have progressed. Patients with a treatment-free interval of at least 6 months lived significantly longer (median 23.6 versus 10.0 months), whereas most side-effect rates were similar in the two groups; severe anemia was somewhat more common, and hypothyroidism less common, in patients with a short treatment-free interval. The treatment-free interval, which is available for every patient at no additional cost, can help clinicians counsel patients about the survival and the adverse-event profile observed in each treatment-free interval group. Because all patients received the same treatment, this difference most likely reflects the more aggressive biology of tumors that recur quickly, not a difference in how well the treatment works or any advantage of delaying it.