E.Y.R. and N.N.S. have no disclosures to report. J.L.G.B. reports the following disclosures: she received grant support from NCI P30 CA008748 and NCI P50 CA217694. She also receives support from the COG, the consortium that sponsored this trial through NIH National Clinical Trials Network grants U10CA180886 and UM1CA228823. She was part of the leadership for the NCI MATCH trial and the principal investigator of a different subarm (subarm H; APEC1621H), directed at a different molecular target, but had no role in the planning of subarm C (APEC1621C). She has served as a paid consultant for Jazz Pharmaceuticals (limited to 1 pediatric advisory board), an uncompensated consultant on the data and safety monitoring board for Springworks, Merck, and Pfizer and an uncompensated consultant on pediatric advisory boards for BMS and Eisai. She receives institutional research support for clinical trials from Jazz Pharmaceuticals, Lilly, Eisai, Loxo-Oncology, Cellectar, and Bayer.