Abstract
BackgroundSince 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.MethodsThis 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.ResultsAmong 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.ConclusionChoice 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.
Highlights
Since treatment patterns in metastatic soft tissue sarcoma 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
Most sarcomas are sensitive to gemcitabine/docetaxel and doxorubicin; angiosarcomas are sensitive to taxanes, liposarcomas are sensitive to doxorubicin-based regimens, synovial sarcomas are sensitive to ifosfamide and leiomyosarcomas are sensitive to gemcitabine, doxorubicin, ifosfamide, and trabectedin [4, 7, 8]
Sensitivity analyses To investigate the potential impact of the inadvertent inclusion of patients without mSTS in our study population due to limitations associated with using medical claims to identify patients with mSTS, two sensitivity analyses evaluated changes to study findings when more restrictive claims diagnostic criteria were applied to Soft tissue sarcoma (STS) population identification
Summary
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. The choice of chemotherapy in metastatic STS (mSTS) should be individualized based on empirical knowledge. The first targeted therapy for STS, was approved by the US Food and Drug Administration (FDA) in April 2012 for mSTS among patients with prior chemotherapy [9]; subsequently, olaratumab was approved in the US in October 2016 for treatment of soft tissue sarcomas [10]. National Comprehensive Cancer Network (NCCN) treatment recommendations include single agents (including dacarbazine, doxorubicin and ifosfamide), anthracycline-based combination regimens, or targeted therapy with pazopanib for relapsed or advanced/metastatic disease [2]. Single agent therapies are typically used in the metastatic setting, whereas chemotherapy combinations are generally used in the neoadjuvant/adjuvant setting or in settings where response is favored
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