PURPOSE: The platelet-derived growth factor receptor (PDGFR) has an important 
role in tumorigenesis and tumor progression. Olaratumab (IMC-3G3) is a fully 
human monoclonal antibody that selectively binds human PDGFRα and blocks ligand 
binding. This phase I study assessed the safety, maximum tolerated dose (MTD), 
recommended phase II dose (RP2D), pharmacokinetics, and preliminary antitumor 
activity of olaratumab in patients with advanced solid tumors.
METHODS: Patients were enrolled into five dose-escalating cohorts of 3-6 
patients each. Olaratumab was administered intravenously weekly at 4, 8, or 16 
mg/kg (cohorts 1-3) or once every other week at 15 or 20 mg/kg (cohorts 4-5), 
with 4 weeks/cycle.
RESULTS: Nineteen patients were treated in five cohorts. There were no 
dose-limiting toxicities; the MTD was not identified with the doses studied. The 
most common olaratumab-related adverse events (AE) were fatigue and infusion 
reactions (10.5 % each). With the exception of 1 patient (20 mg/kg) experiencing 
two grade 3 drug-related AEs after the dose-limiting toxicity assessment period, 
all drug-related AEs were grade 1 or 2. The trough concentrations (C min) for 16 
mg/kg weekly and 20 mg/kg biweekly were higher than 155 μg/mL, and the 
concentration found to be efficacious in preclinical xenograft models. Twelve 
patients (63.2 %) had a best response of stable disease [median duration of 3.9 
months (95 % CI 2.3-8.7)].
CONCLUSIONS: Olaratumab was well tolerated and showed preliminary antitumor 
activity. RP2Ds are 16 mg/kg weekly and 20 mg/kg biweekly. Phase II studies of 
olaratumab as monotherapy and in combination are ongoing in several tumor types.