A pilot study of first-line olaratumab, doxorubicin and ifosfamide in patients with metastatic soft tissue sarcoma.

Abstract

Olaratumab (O) is a monoclonal antibody that specifically binds PDGFRα. The addition of O to doxorubicin (D) has been approved by the regulatory authorities for metastatic soft tissue sarcoma (MSTS). Since the combination of D + ifosfamide (I) is commonly used in MSTS and is associated with a higher response rate than D alone, it seems reasonable to combine O with the combination of D + I (ODI). We report our preliminary experience with O + D+I in MSTS. Between 01/01/2015 and 30/05/2018, 15 patients (pts) with MSTS were treated with ODI as first-line therapy. The treatment protocol consisted of IV D 50mg/m2 and I 5000mg/m2, day 1 (3 pts), or D 37.5mg/m2 and I 3000mg/m2 days 1-2 (12 pts). O (15mg/kg) was given IV on days 1, 8, and cycles were repeated every 21days. With a median follow up of 16months, 63 cycles of ODI were given. Objective response was achieved in 4 pts (27%) (CR in 3, PR in 1); 5 pts (33%) remained with stable disease for ≥ 5 mo. Median overall survival was 22months. Major hematological toxicities (grade 3-4) included: neutropenia-7 pts (47%), and neutropenic fever-3 pts (20%). Non-hematological toxicities included grade 3 diarrheas in 2 pts (13%) after the second cycle. There was no treatment-related mortality. According to our preliminary experience, adding olaratumab to doxorubicin and ifosfamide is active and its safety profile is comparable to that of doxorubicin and ifosfamide alone in MSTS.