Testing the Use of Neratinib or the Combination of Neratinib and Palbociclib Targeted Treatment for HER2+ Solid Tumors (A ComboMATCH Treatment Trial)

Inclusion Criteria: * Patient must have enrolled onto EAY191 and must have been given a treatment assignment to ComboMATCH to EAY191-N5 based on the presence of an actionable mutation as defined in EAY191 * Patients must have a HER2 amplified solid tumor except breast cancer. * If IHC is 0 or 1+, patient (pt) is NOT ELIGIBLE regardless of in situ hybridization (ISH)/FISH or next generation sequencing (NGS) status * If IHC is 3+, pt IS ELIGIBLE regardless of ISH/FISH or NGS status * If IHC is 2+, ISH/FISH OR NGS must be positive for the patient to be ELIGIBLE. Otherwise, pt is NOT ELIGIBLE * If IHC is unknown and… * ISH/FISH is positive, independent of NGS results, the patient IS ELIGIBLE * ISH/FISH is negative and NGS positive with ≥ 7 copies, the patient IS ELIGIBLE * Patients must have recurrent or persistent disease * No known evidence of RB1 loss or deletion including copy number loss or deleterious mutation * Patients must have disease that can be safely biopsied and agree to a pre-treatment biopsy or, if disease cannot be safely biopsied, have archival tissue available from within 12 months prior to the date of registration on the ComboMATCH Registration Trial (EAY191) * Patients must have measurable disease based on RECIST 1.1. A second measurable lesion outside of the biopsiable lesion is required * Patients with treated brain metastases are eligible if follow up brain imaging after central nervous system (CNS) directed therapy shows no evidence of …