A retrospective cohort study of treatment patterns among patients with metastatic soft tissue sarcoma in the US

Since treatment patterns in metastatic soft tissue sarcoma (mSTS) have not been studied subsequent to US approval of pazopanib in 2012, this study sought to examine mSTS treatment patterns by line of therapy, including regimen and duration of therapy.

This retrospective study employed administrative claims from a large US health plan from 1/2006-9/2015. Adult mSTS patients were required to have an NCCN-recommended therapy and be continuously enrolled in the health plan during the study period. The most frequent regimens for distinct lines of therapy (LOT) were assessed. Sensitivity analyses evaluated changes to study findings using two alternate medical and pharmacy claims diagnostic algorithms to define the STS study population.

Among 555 patients with mSTS, mean age was 59 years and 54% were male. During the study period, 41% of patients initiated ≥ 2 LOTs; 16% had ≥ 3 LOTs and 5% had ≥ 4 LOTs. Docetaxel + gemcitabine was most common in LOT1, pazopanib in LOT2 and LOT3, and doxorubicin in LOT4. The five most common LOT1 regimens represented 53% of patients; among the remaining 47%, the most common regimen represented < 6% of patients. Among patients with pazopanib in LOT2 and LOT3, the most common prior regimen was docetaxel + gemcitabine (47% and 30% respectively). Kaplan-Meier estimation of median treatment duration overall for LOT1 was 3.5 months, while for LOT2 and LOT3, median treatment duration was 2.9 and 3.3 months, respectively. For both sensitivity analyses, patient demographic and clinical characteristics were similar to the original study population, and the five most frequently used regimens in LOT1 and LOT2 were similar among the three populations regardless of the population selection criteria employed.

Choice of regimen by LOT among patients with mSTS is varied; < 65% of patients in any LOT received the five most common regimens. Pazopanib, the only approved targeted therapy, is primarily used in second and later lines of therapy and is mostly given post docetaxel + gemcitabine.