A Study of Abemaciclib (LY2835219) in Combination With Other Anti-Cancer Treatments in Children and Young Adult Participants With Solid Tumors, Including Neuroblastoma

Inclusion Criteria: * Parts A and B only: * Participants must be less than or equal to (≤)18 years of age. * Body weight greater than or equal to (≥)10 kilograms and body surface area (BSA) ≥0.5 * Participants with any relapsed/refractory malignant solid tumor (excluding lymphoma), including central nervous system tumors, that have progressed on standard therapies. * For sites that are actively enrolling Parts B and C, participants with neuroblastoma who are eligible for Part C will be excluded from Part B unless approved by Lilly CRP/CRS. * Part C only: * Participants must be less than (\<) 21 years of age. * Participants have a BSA ≥0.2 m². * Participants with first relapse/refractory neuroblastoma. * All Parts * Participants must have measurable or evaluable disease by RECIST v1.1 or RANO. * A Lansky score ≥50 for participants \<16 years of age or Karnofsky score ≥50 for participants ≥16 years of age. * Participants must have discontinued all previous treatments for cancer or investigational agents and must have recovered from the acute effects to Grade ≤1 at the time of enrollment. * Able to swallow and/or have a gastric/nasogastric tube. * Adequate hematologic and organ function ≤2 weeks (14 days) prior to first dose of study drug. * Females of reproductive potential must have negative urine or serum pregnancy test at baseline (within 7 days prior to starting treatment). * Female participants of reproductive potential must agree to use hig…