Patient description: A 17 year old boy complains of vomiting, non-bloody diarrhea, abdominal pain, fever, chills and loss of appetite for the past 3 days. He ate a salad at a restaurant prior to his diarrhea onset. Physical exam was remarkable for pallor, jaundice, and diffuse abdominal tenderness. Lab results were as follows: Hemoglobin: 9.7 g/dL Platelet: 110,000 /cu.mm Creatinine: 3.6 mg/dL blood urea nitrogen (BUN): 73 mg/dL direct bilirubin: 2.4 mg/dL lactate dehydrogenase (LDH): 881 IU/L (normal: 110-265 IU/L) Peripheral blood smear showed a moderate number of schistocytes and helmet cells. Shiga-like toxin-producing E. coli (STEC) stx1/stx2 were found in stools. He has no other underlying disease and he is not on any medications.

Clinical trial eligibility criteria: eligible ages (years): 15.0-999.0,  Advanced Malignant Solid Neoplasm C-KIT Tyrosine Kinase Protein Overexpression Clinical Stage IV Cutaneous Melanoma AJCC v8 Metastatic Gastrointestinal Stromal Tumor Metastatic Malignant Solid Neoplasm Metastatic Melanoma Pathologic Stage IV Cutaneous Melanoma AJCC v8 Unresectable Melanoma Unresectable Solid Neoplasm For dose escalation study, patients must have histological confirmation of solid tumors that is metastatic or unresectable. For expansion cohorts, patients must have metastatic or unresectable gastrointestinal stromal tumor (GIST), melanoma, or uncategorized tumors with tumor biopsies that are positive for c-KIT mutations by polymerase chain reaction (PCR) or immunohistochemistry (IHC). For patients enrolled in the melanoma expansion cohort, only select KIT mutations will be eligible. Patients with mutations in exon 13 V654X, 14 T6701, 17 D816X and all exon 18 mutations will not be eligible for enrollment Patients who have completed previous therapies 4-weeks prior to (or within 5 drug half lives) enrollment on study. Radiation therapy wash out period will be 2 weeks. This includes an exception of patients with metastatic GIST tumors who are taking maintenance imatinib mesylate therapy. These patients are allowed to remain on imatinib mesylate therapy up to enrollment in this study Eastern Cooperative Oncology Group (ECOG) performance status < 2 (Karnofsky > 60%) Leukocytes > 3,000/mcL Absolute neutrophil count > 1,500/mcL Platelets > 100,000/mcL Total bilirubin < or = 2.0 mg/dL. (Does NOT apply to patients with Gilbert's syndrome) Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase [SGOT])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase [SGPT]) < 2.5 X institutional upper limit of normal (patients with liver involvement will be allowed < or = 5.0 X institutional upper normal limit) Serum creatinine < 2.0 mg/dL Patients MUST have recovered from all treatment related toxicities to grade 1 National Center Institute (NCI) Common Terminology for Adverse Events (CTCAE) (version [v] 4.0) in severity  Autoimmune disease: Patients with a history of inflammatory bowel disease (including Crohn's disease and ulcerative colitis) and autoimmune disorders such as rheumatoid arthritis, systemic progressive sclerosis [scleroderma], systemic lupus erythematosus or autoimmune vasculitis [e.g., Wegener's granulomatosis] are excluded from this study History of acute diverticulitis, intra-abdominal abscess, gastrointestinal (GI) obstruction, abdominal carcinomatosis or other known risk factors for bowel perforation Any underlying medical or psychiatric condition, which in the opinion of the Investigator, will make the administration of study drug hazardous or obscure the interpretation of adverse events (AEs): e.g. a condition associated with frequent diarrhea or chronic skin conditions, recent surgery or colonic biopsy from which the patient has not recovered, or partial endocrine organ deficiencies Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, history of congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements Known human immunodeficiency virus (HIV), hepatitis B, or hepatitis C Any non-oncology live vaccine therapy used for prevention of infectious diseases (for up to one month prior to or after any dose of ipilimumab) Concomitant therapy with any of the following: IL-2, interferon or other non-study immunotherapy regimens; cytotoxic chemotherapy; immunosuppressive agents; other investigational therapies; or chronic use of systemic corticosteroids (when used in the management of cancers other than intracranial glioblastoma, gliosarcoma or anaplastic astrocytoma, or when used to treat non-cancer-related illnesses) Patients who do not agree to practice appropriate birth control methods while on therapy Pregnant women are excluded from this study. Women of child-bearing potential and men must agree to use contraception prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician