Olaratumab (IMC-3G3) is a fully human IgG1 monoclonal antibody that selectively 
binds the external domain of human platelet-derived growth factor receptor-α 
with high affinity and blocks ligand binding. This was a single-center, 
dose-escalation, phase I trial of olaratumab in Japanese patients with 
advanced/refractory solid malignancies. Three to six patients were enrolled into 
each of three cohorts: Patients received i.v. olaratumab: 10 mg/kg on days 1 and 
8 every 3 weeks (cohort 1); 20 mg/kg every 2 weeks (cohort 2); and 15 mg/kg on 
days 1 and 8 every 3 weeks (cohort 3). Doses were escalated from cohort 1 
through cohort 3. The primary objective was to establish the safety and 
pharmacokinetic profile of olaratumab. Sixteen patients were treated across 
three cohorts. There were no dose-limiting toxicities, so the maximum tolerated 
dose was not reached. The most common olaratumab-related treatment-emergent 
adverse events (TEAEs) were proteinuria (25.0%) and elevated aspartate 
transaminase (12.5%). One patient (cohort 2) had two olaratumab-related Grade 3 
TEAEs (increased aspartate aminotransferase and tumor hemorrhage); otherwise, 
olaratumab-related TEAEs were Grade 1/2. Seven patients (43.8%) had a best 
response of stable disease. Based on the pharmacokinetic concentration profile 
of olaratumab, the trough concentrations following single and multiple doses at 
15 mg/kg on days 1 and 8 every 3 weeks (cohort 3) and multiple doses at 20 mg/kg 
every 2 weeks (cohort 2) were above the 155 μg/mL target. Thus, these two doses 
could represent an acceptable schedule for future trials in Japanese patients. 
Olaratumab had an acceptable safety profile and was well tolerated.