Combination therapy with Olaratumab/doxorubicin in advanced or metastatic soft tissue sarcoma -a single-Centre experience

Background The antibody targeting platelet-derived growth factor receptor alpha (PDGFRA), olaratumab, was approved in 2016 for metastatic soft tissue sarcoma (STS) in combination with doxorubicin based on promising results of a phase Ib/II trial by the Food and Drug Administration (FDA). However, recently the phase III ANNOUNCE trial could not confirm the additional value of olaratumab in this context. Methods Here, in a retrospective analysis we share our single-centre experience with olaratumab/doxorubicin in STS by including n = 32 patients treated with olaratumab/doxorubicin between 2016 and 2019. Results Median progression-free survival (PFS) in the overall cohort was 3.1 months (range 0.6-16.2). A response [complete remission (CR), partial remission (PR) or stable disease (SD)] was seen in n = 11 (34%) cases, whereas n = 21 (66%) patients showed progressive disease (PD). In n = 9 patients surgery was performed subsequently in an individual therapeutic approach. Out of n = 5 patients receiving additional regional hyperthermia, n = 3 achieved PR or SD. Conclusions This single-centre experience does also not support the promising phase Ib/II results for olaratumab/doxorubicin in STS. However, our findings do not preclude that olaratumab combination therapy could be valuable in a neoadjuvant setting. This warrants further exploration also taking into account the heterogeneous nature of STS.