A Study of Olaratumab Alone and in Combination With Standard Chemotherapies in Children With Cancer

Inclusion Criteria:

* The participant must have histological or cytological evidence of a diagnosis of solid tumor, excluding lymphomas and melanoma, but including central nervous system (CNS) tumors, that is relapsed or refractory, not be amenable to curative treatment.
* The participant has the presence of measurable and/or nonmeasurable but evaluable disease as defined by the Response Evaluation Criteria In Solid Tumors (RECIST Version 1.1). Response Assessment in Neuro-Oncology (RANO) Criteria or Macdonald Criteria should be used for CNS tumors.
* The participant has a Lansky (\<16 years of age) or Karnofsky (≥16 years of age) performance score of at least 50.
* The participant has adequate hematologic, organ, and coagulation function ≤2 weeks (14 days) prior to first dose of study drug:

  * Absolute neutrophil count (ANC) ≥750 cubic millimeters (mm³)
  * Platelets ≥75,000/mm³
  * Hemoglobin ≥8 grams per deciliter (g/dL)
  * Total bilirubin (sum of conjugated + unconjugated) ≤1.5 x upper limit of normal (ULN) for age
  * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3.0 x ULN
  * Serum creatinine is based on age/gender
  * Adequate coagulation function as defined by International Normalized Ratio ≤1.5 or prothrombin time ≤1.5 x ULN, and partial thromboplastin time ≤1.5 x ULN
* Both female and male participants of child-bearing potential must agree to use highly effective contraceptive precautions during the trial and up to 3 months following the last dose of olaratumab, or longer for other study drugs according to their label.
* Participants must have fully recovered from the acute toxic effects of all prior anticancer therapies or must adhere to post-treatment conditions as follows:

  * Myelosuppressive chemotherapy
  * Hematopoietic growth factors
  * Biologic (anti-neoplastic agent)
  * Antibody therapy
  * Radiation
  * Stem cell infusion without traumatic brain injury
  * Corticosteroids

Exclusion Criteria:

* Have received treatment within 21 days of the initial dose of olaratumab with an investigational product or non-approved use of a drug or device or are concurrently enrolled in any other type of medical research judged not to be scientifically or medically compatible with this study.
* Participants that have had bone marrow or solid organ transplant are excluded.
* The participant has an active fungal, bacterial, and/or known severe viral infection including human immunodeficiency virus (HIV) or viral (A, B, or C) hepatitis (screening is not required).
* Female participants who are pregnant or breastfeeding are excluded.
* If the participant is to be enrolled in the doxorubicin combination arm, a left ventricular dysfunction (LVEF \< 50%) or shortening fraction of \<27% by echocardiogram (either multigated acquisition \[MUGA\] or echocardiogram \[ECHO\] are required, not both).
* Participants that have received prior anthracycline therapy if the participant is to be enrolled in the doxorubicin combination arm.