Developments in the management of advanced soft-tissue sarcoma – olaratumab in context

Lartruvo(®) (olaratumab) is a fully human immunoglobulin G subclass 1 (IgG1) monoclonal antibody that inhibits platelet-derived growth factor receptor alpha (PDGFRα). The antitumor activity of olaratumab has been tested in vitro and in vivo, and inhibition of tumor growth has been observed in cancer cell lines, including glioblastoma and leiomyosarcoma cells. It represents the first-in-class antibody to be approved by regulatory authorities for the treatment of advanced soft-tissue sarcomas (STSs) in combination with doxorubicin, based on the results of the Phase Ib/II trial by Tap et al. The median progression-free survival (PFS), which was the primary end point of the study, was improved for patients treated with olaratumab plus doxorubicin compared to those treated with doxorubicin monotherapy (6.6 vs 4.1 months, respectively; HR 0.672, 95% CI 0.442–1.021, p=0.0615). Moreover, final analysis of overall survival (OS) showed a median OS of 26.5 months with olaratumab plus doxorubicin vs 14.7 months with doxorubicin, with a gain of 11.8 months (HR 0.46, 95% CI 0.30–0.71, p=0.0003). In October 2016, olaratumab was admitted in the Accelerated Approval Program by the US Food and Drug Administration (FDA) for use in combination with doxorubicin for the treatment of adult patients with STSs. In November 2016, the European Medicines Agency (EMA) granted conditional approval for olaratumab in the same indication under its Accelerated Assessment Program. A double-blind, placebo-controlled, randomized Phase III study (ANNOUNCE trial, NCT02451943) is being performed in order to confirm the survival advantage of olaratumab and to provide definitive drug confirmation by regulators. The study is ongoing, but enrollment is closed. The purpose of this review was to evaluate the rationale of olaratumab in the treatment of advanced STSs and its emerging role in clinical practice.