Olaratumab for soft tissue sarcoma

Soft tissue sarcomas (STS) are rare malignant tumors. Unfortunately, the first-line doxorubicin-based treatment has not been improved since the 1970s. Platelet-derived growth factor (PDGF) receptor alpha (PDGFR-α) and its ligands are co-expressed in many types of cancer, including sarcomas. They are involved in stimulating growth and regulating stromal-derived fibroblasts and angiogenesis. PDGFR-α and its ligand may play an important role in tumorigenesis and be a potential target in the treatment of sarcomas. Olaratumab is a fully human IgG1-type anti-PDGFR-α monoclonal antibody with a high affinity and a low 50% inhibitory concentration (IC50). Areas covered: The authors review the role of olaratumab in the treatment of STS by focusing on the recent, randomized Phase II JDGD trial that challenged patients with unresectable or metastatic STS with doxorubicin in the presence or absence of olaratumab. This trial showed a great improvement in overall survival (OS), with an increase in survival from 14.7 months to 26.5 months for patients in the experimental arm and showed acceptable toxicity. Expert opinion: Results seem promising. However, it must be qualified, as the study includes several uncertainties. These uncertainties should be addressed by the ongoing Phase 3 JGDJ confirmatory trial, for which the final efficacy analysis is expected by 2019.