Patient description: The patient is a 41-year-old man and a known case of Acromegaly who underwent transsphenoidal surgery 4 months ago. He came to the clinic for the follow up lab studies after his primary resection surgery. His lab study shows the IGF-1 level of 4.5 ULN adjusted by sex and age. His random GH level is 4 ug/L. The recent brain MRI confirmed the residual pituitary tumor. His past medical history is only significant for acromegaly due to pituitary adenoma and the recent surgery. After his surgery he takes only vitamin D and multivitamins.

Clinical trial eligibility criteria: eligible ages (years): 1.0-21.0,  Advanced Malignant Solid Neoplasm Recurrent Ependymal Tumor Recurrent Ewing Sarcoma Recurrent Glioma Recurrent Hepatoblastoma Recurrent Histiocytic and Dendritic Cell Neoplasm Recurrent Langerhans Cell Histiocytosis Recurrent Malignant Germ Cell Tumor Recurrent Malignant Solid Neoplasm Recurrent Medulloblastoma Recurrent Neuroblastoma Recurrent Non-Hodgkin Lymphoma Recurrent Osteosarcoma Recurrent Peripheral Primitive Neuroectodermal Tumor Recurrent Primary Malignant Central Nervous System Neoplasm Recurrent Rhabdoid Tumor Recurrent Rhabdomyosarcoma Recurrent Soft Tissue Sarcoma Refractory Ependymoma Refractory Ewing Sarcoma Refractory Glioma Refractory Hepatoblastoma Refractory Histiocytic and Dendritic Cell Neoplasm Refractory Langerhans Cell Histiocytosis Refractory Malignant Germ Cell Tumor Refractory Malignant Solid Neoplasm Refractory Medulloblastoma Refractory Neuroblastoma Refractory Non-Hodgkin Lymphoma Refractory Osteosarcoma Refractory Peripheral Primitive Neuroectodermal Tumor Refractory Primary Malignant Central Nervous System Neoplasm Refractory Rhabdoid Tumor Refractory Rhabdomyosarcoma Refractory Soft Tissue Sarcoma Wilms Tumor Patient must have enrolled onto APEC1621SC and must have been given a treatment assignment to MATCH to APEC1621J based on the presence of an actionable mutation Patients must have a body surface area >= 0.54 m^2 at the time of study enrollment Patients must have radiographically measurable disease at the time of study enrollment. Patients with neuroblastoma who do not have measurable disease but have metaiodobenzylguanidine (MIBG)+ evaluable disease are eligible. Measurable disease in patients with central nervous system (CNS) involvement is defined as tumor that is measurable in two perpendicular diameters on magnetic resonance imaging (MRI) and visible on more than one slice Note: The following do not qualify as measurable disease Malignant fluid collections (e.g., ascites, pleural effusions) Bone marrow infiltration except that detected by MIBG scan for neuroblastoma Lesions only detected by nuclear medicine studies (e.g., bone, gallium or positron emission tomography [PET] scans) except as noted for neuroblastoma Elevated tumor markers in plasma or cerebrospinal fluid (CSF) Previously radiated lesions that have not demonstrated clear progression post radiation Leptomeningeal lesions that do not meet the measurement requirements for Response Evaluation in Solid Tumors (RECIST) 1.1  Pregnant or breast-feeding women will not be entered on this study due to risks of fetal and teratogenic adverse events as seen in animal/human studies. Pregnancy tests must be obtained in girls who are post-menarchal. Males or females of reproductive potential may not participate unless they have agreed to use an effective contraceptive method for the duration of study treatment and for 3 months after last dose of BVD-523FB (ulixertinib) Patients receiving corticosteroids who have not been on a stable or decreasing dose of corticosteroid for at least 7 days prior to enrollment are not eligible. If used to modify immune adverse events related to prior therapy, >= 14 days must have elapsed since last dose of corticosteroid Patients who are currently receiving another investigational drug are not eligible Patients who are currently receiving other anti-cancer agents are not eligible Patients who are receiving cyclosporine, tacrolimus or other agents to prevent graft-versus-host disease post bone marrow transplant are not eligible for this trial Patients who are currently receiving drugs that are strong inducers or inhibitors of CYP3A4 are not eligible. Strong inducers or inhibitors of CYP3A4 should be avoided from 14 days prior to enrollment to the end of the study. Note: CYP3A4 inducing anti-epileptic drugs and dexamethasone for CNS tumors or metastases, on a stable dose, are allowed Patients who are currently receiving drugs that are strong inducers or inhibitors of CYP1A2 and CYP2D6 are not eligible. Strong inhibitors of CYP1A2 (e.g., ciprofloxacin, enoxacin, fluvoxamine, zafirlukast) should be avoided from 14 days prior to enrollment to the end of the study. Strong inhibitors of CYP2D6 (e.g., bupropion, paroxetine, fluoxetine, quinidine, terbinafine) should also be avoided from 14 days prior to enrollment to the end of the study Patients with known significant ophthalmologic conditions (uncontrolled glaucoma, history of retinal vein occlusion or retinal detachment, excluding patients with longstanding findings secondary to existing conditions) are not eligible Patients who have an uncontrolled infection are not eligible Patients who have received a prior solid organ transplantation are not eligible