Ability to swallow entrectinib intact The subject has a gastrointestinal disease that would prevent him or her from being able to swallow or absorb flucytosine Patients unable to swallow capsules whole are not eligible; nasogastric or gastric (G) tube administration is not allowed Patients must be able to swallow tablets or capsules; a patient with any gastrointestinal disease that would impair ability to swallow, retain, or absorb drug is not eligible Subject must be able to swallow solid dosage forms. Subjects must be able to swallow whole capsule. Patients must be able to swallow capsules; nasogastric or gastrostomy feeding (G) tube administration is not allowed Ability to swallow the study drugs Patients must be able to swallow whole tablets or capsules; nasogastric or gastrostomy tube (G-tube) administration is not allowed Patients must be able to swallow whole tablets or capsules; nasogastric or gastrostomy tube (G-tube) administration is not allowed; any gastrointestinal disease which would impair ability to swallow, retain, or absorb drug is not allowed Participant must be able to swallow tablets or capsules. A participant with any gastrointestinal disease that would impair ability to swallow, retain, or absorb drug is not eligible. STRATUM A: Participant must be able to swallow medication; it is acceptable to administer medication via a gastrostomy tube (g-tube) if participant has a g-tube; it is not acceptable to place a g-tube for the purpose of delivering study medication STRATUM B: Participant must be able to swallow medication; it is acceptable to administer medication via a g-tube if participant has a g-tube; it is not acceptable to place a g-tube for the purpose of delivering study medication STRATUM C: Participant must be able to swallow medication; it is acceptable to administer medication via a g-tube if participant has a g-tube; it is not acceptable to place a g-tube for the purpose of delivering study medication Able to swallow study drug Must be able to swallow ribociclib and oral aromatase inhibitor, such as letrozole Patients must be able to swallow whole capsules; nasogastric or gastrointestinal (G)-tube administration is not allowed Able to swallow the study drugs whole The subject must be able to swallow ribociclib (LEE) Patient has a condition that would prevent him or her from being able to swallow Toca FC tablets or absorb flucytosine. Patients who are not able to swallow the lenalidomide capsule as a whole are excluded from this study; (capsule cannot be opened, chewed, or crushed) Other Requirements\r\n* Patients must be able to give informed consent\r\n* Patients must have ECOG performance status , or and/or Karnofsky performance status (KPS) > \r\n* Patients must be able to swallow\r\n* Patients must be able to sit up with or without assistance\r\n* Patients must be able to undergo contrast-enhanced MRI (Cohort D) Capacity to swallow Patients who are unable to swallow the medication in its prescribed form are not eligible; the drug cannot be administered via gastric feeding (G)-tube; there will be no exceptions for this criteria Able to swallow and absorb the medication Able to swallow or have medication administered through a gastrostomy tube (G-tube) and absorb the medication Able to swallow or have medication administered through a gastrostomy (G)-tube and absorb the medication Willingness and ability to swallow study drugs Patients must be able to swallow whole tablets or capsules; nasogastric or gastrostomy (G)-tube administration is not allowed; any gastrointestinal disease which would impair ability to swallow, retain, or absorb drug is not allowed Patients must be able to swallow the drug Parts A and B: Patients who are able to swallow liquid or use a nasogastric or gastrostomy (G) tube are eligible Patients taking the capsule formulation must be able to swallow capsules; feeding tube administration is allowed for patients receiving the oral solution (OS) Inability to swallow or absorb orally-administered medication. Patients must be able to swallow whole capsule Able to swallow oral formulation of the study agent Able to swallow thin liquids or have a feeding tube for delivery of nutrition Ability to swallow liquids Able to swallow and absorb the medication Adequate swallowing function or gastric-tube for drug administration; of note, lapatinib can be administered via gastrostomy (G)-tube in a slurry for patients who cannot swallow Patients must be able to swallow the vorinostat capsules or have a feeding tube to allow for drug suspension Able to swallow medication Able to swallow the study drugs whole. Subject must be able to swallow medication Ability to swallow the study drugs whole. Patients who are not able to swallow the lenalidomide capsule as a whole are excluded from this study (capsule cannot be opened, chewed, or crushed) Does the subject have any gastrointestinal disease that would prevent him or her from being able to swallow or absorb flucytosine? Ability to swallow study drug whole as a capsule Patients must be able to swallow capsules whole; nasogastric or gastrostomy (G) tube administration is not allowed Ability to swallow the study drugs Able to swallow the study drug (no contraindication to oral agents). Able to swallow the study drug (no contra indication to oral agents). Able to swallow thin liquids Able to swallow supplements Able to swallow medication Participants must be able to swallow the oral doses of erlotinib and PPE Patient is able to swallow a capsule Be able to swallow medication Patients must be able to swallow whole tablets or capsules; nasogastric or g-tube administration is not allowed; any gastrointestinal disease which would impair ability to swallow, retain, or absorb drug is not allowed