Patient description: The patient is a 16-year-old girl recently diagnosed with myasthenia gravis, class IIa. She complains of diplopia and weakness affecting in her upper extremities. She had a positive anti-AChR antibody test, and her single fiber electromyography (SFEMG) was positive. She is on acetylcholinesterase inhibitor treatment combined with immunosuppressants. But she still has some symptoms. She does not smoke or use illicit drugs. She is not sexually active, and her menses are regular. Her physical exam and lab studies are not remarkable for any other abnormalities. BP: 110/75 Hgb: 11 g/dl WBC: 8000 /mm3 Plt: 300000 /ml Creatinine: 0.5 mg/dl BUN: 10 mg/dl Beta hcg: negative for pregnancy

Clinical trial eligibility criteria: eligible ages (years): 1.0-20.0,  Advanced Malignant Solid Neoplasm Recurrent Brain Neoplasm Recurrent Malignant Solid Neoplasm Refractory Brain Neoplasm Patients must be >/= 12 months and < 21 years of age at the time of study enrollment Patients must have had a previous histological verification of a solid tumor at the original diagnosis and/or recurrence including brain tumors; for patients with brain stem gliomas and optic pathway tumors, the requirement for histological evaluation may be waived; the patient's disease must be considered refractory to conventional/standard therapy, or a disease for which no conventional therapy exists and is progressive The patient must have a stable clinical (neurologic in case of brain tumors) exam and be on a stable dose of steroids for at least 1 week prior to study entry; the patient should have a measurable and/or evaluable disease; measurable disease which is defined as the presence of at least one lesion that can be accurately measured in two dimensions (each measures at least 10 mm) or evaluable disease which is defined as at least one lesion that can be accurately measured in at least one dimension (measure at least 10 mm) Karnofsky performance status >= 50 for patients >= 16 years of age and a Lansky performance status >= 50 for patients aged < 16 years Life expectancy: must be >= 12 weeks Chemotherapy Must not have received myelosuppressive chemotherapy within 3 weeks of the study entry (6 weeks if prior nitrosourea); prior treatment with either dasatinib or temsirolimus but not both is allowed; at least 3 weeks must have elapsed from the last dose Biologic therapy (anti-neoplastic) Must not have received oral tyrosine kinase inhibitors (other than dasatinib) or other similar agents within 3 weeks of the study entry and all toxicities must have resolved to < grade 2 prior to enrollment Must not have received bevacizumab or other monoclonal antibody therapy within 4 weeks of study the entry  Patients with evidence of recent intratumoral hemorrhage (within 3 months of study enrollment), gastrointestinal bleeding, history of coronary artery disease or on anticoagulation therapy Pregnant or breast-feeding women will not be entered on this study Uncontrolled current illness including, but not limited to, uncontrolled infection, need for hemodialysis, need for ventilatory support, psychiatric illness/social situations that would limit compliance with study requirements History of hypersensitivity to any component of the formulation Patients with known human immunodeficiency virus (HIV) are ineligible for this study Patients must not have received prior therapy with dasatinib and temsirolimus for any indication Patients with clinically significant cardiovascular disease: history of ischemic or hemorrhagic stroke within past 6 months; uncontrolled hypertension, on at least 2 repeated determinations on separate days within past 3 months; myocardial infarction or unstable angina within past 6 months; New York Heart Association grade III or greater congestive heart failure, serious cardiac arrhythmia requiring medication, unstable angina pectoris within past 6 months; clinically significant peripheral vascular disease within past 6 months; pulmonary embolism, deep vein thrombosis (DVT), or other thromboembolic event within past 6 months; diagnosed congenital long QT syndrome; any history of clinically significant ventricular arrhythmias (such as ventricular tachycardia, ventricular fibrillation, or torsades de pointes); prolonged QTc interval on pre-entry electrocardiogram (> 450 msec); subjects with hypokalemia or hypomagnesemia if it cannot be corrected prior to dasatinib administration Anticonvulsants: patients on enzyme inducing anticonvulsants (EIAED) will be excluded; if patients were previously on EIAEDs that have been discontinued, patients must have been off EIAEDs for >= 2 weeks prior to initiation of dasatinib Anticoagulants/anti-platelets: patients on therapeutic (treatment) dose of anticoagulants (e.g. warfarin, low molecular-weight heparin) are not eligible; patients are not allowed to take aspirin, clopidogrel, ticlopidine, Aggrenox; patients on prophylactic anticoagulation may be enrolled and treated on study as long as their platelet count is monitored closely and maintained at > 75,000 while they are receiving dasatinib Inducers and Inhibitors of cytochrome P450 family 3, subfamily A, polypeptide 4 (CYP3A4): patients required to be on any CYP3A4/5 inhibitors or inducers will be excluded (with the exception of dexamethasone, but all efforts should be made to reduce the dose of dexamethasone); patients must discontinue drug at least 7 days prior to starting dasatinib