PFS is measured from randomization until the first radiographic documentation of progression of disease (PD) as defined by Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1) or death from any cause. Participants who died without PD was considered to have progressed on the day of death. The following censoring rules applied: If no radiologic assessment at baseline or post baseline, participant was censored at the date of randomization. Participants were censored at the day of their last tumor assessment if no PD and were lost to follow up; If death or PD occurred after 2 or more consecutive missing radiographic visits, censoring occurred at the date of the last adequate radiographic visit. If participant started new treatment before PD, the participant was censored at the date of last tumor assessment prior to new therapy. If treatment was discontinued for reasons other than PD and no further assessment, censoring occurred at last tumor assessment.

All randomized participants in Phase 2. Per protocol, phase 1b and optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure. Censored Participants = Phase 2 Olaratumab + Doxorubicin = 11 and Doxorubicin = 19.

All Phase 1b participants who experienced at least 1 TEAE in the Phase 1b portion of the study. Adverse Event with missing relationship to study is counted as related. A summary of SAEs and all other non-serious AEs, regardless of causality, is located in the Reported Adverse Event module.

All participants in Phase 1b.

A summary of SAEs and all other non-serious AEs, regardless of causality, is located in the Reported Adverse Event module.

All randomized participants who received at least 1 dose of study drug in Phase 2 and optional Olaratumab monotherapy.

OS was defined as the date of randomization to the date of death from any cause. Reasons for censoring OS were that participant was known to be alive, participant was lost to follow up during the study or participant withdrew consent to follow up.

All randomized participants in Phase 2. Per protocol, phase 1b and optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure. Censored participants = Phase 2 Olaratumab + Doxorubicin = 27 and Doxorubicin = 15.

Objective Response Rate (ORR) is confirmed best overall tumor response of CR or PR. According to RECIST v1.1, PR defined as a >30% decrease in the sum of the longest diameters (LD) of the target lesions, taking as reference the baseline sum of the LD; CR was defined as the disappearance of all target and non-target lesions. Percentage of participants was calculated as: total number of participants with a best tumor response of PR or CR among participants counted in the denominator/total number of participants treated with any amount of study drug, who has a complete radiographic assessment at baseline, and who has at least 1 complete radiographic assessment at postbaseline x 100%.

All randomized participants in Phase 2 and optional Olaratumab monotherapy.

(PFS) rate is defined as the percentage of participants that are alive and progression-free 3 months after randomization. PFS is measured from randomization until the first radiographic progressive disease as defined by RECIST (version 1.1) or death from any cause. Participants who died without PD were considered to have progressed on the day of death. Censoring applied: If no radiologic assessment at baseline or post baseline, participant was censored at the date of randomization or the day of their last tumor assessment if no PD and were lost to follow up; If death or PD occurred after 2 or more consecutive missing radiographic visits, censoring occurred at the date of the last radiographic visit. If participant started new treatment before PD, participant was censored at the date of last tumor assessment prior to new therapy. If treatment was discontinued for reasons other than PD and no further assessment, censoring occurred at last tumor assessment.

All randomized participants in Phase 2. Per protocol, phase 1b and optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure. Censored Participants = Phase 2 Olaratumab + Doxorubicin = 11 and Doxorubicin = 19.

All participants who had evaluable PK data in Phase 1b and Phase 2. Per protocol, optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure.

All participants who had evaluable PK data in Phase 1b and Phase 2. Per protocol, optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure.

AUCτ = area under the concentration versus time curve during one dosing interval with a measurable concentration.

All participants who had evaluable PK data in Phase1b and Phase 2. Per protocol, optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure.

All participants who had evaluable PK data in Phase 1b and Phase 2. Per protocol, optional Olaratumab monotherapy data was exploratory and not collected for this outcome measure.

Participants with Treatment Emergent (TE) anti-olaratumab antibodies were participants with a 4-fold increase (2 dilutions) increase over a positive baseline antibody titer or for a negative baseline titer, a participant with an increase from the baseline to a level of 1:20.

All participants who had baseline and post baseline anti-olaratumab antibodies.