Phase I Study of Safety and Immunogenicity of ADU-623

Inclusion Criteria: * Patients with a pathologic diagnosis of WHO Grade III or Grade IV astrocytic tumors that have completed standard of care or with radiographic evidence of progression following standard of care. * Tumor tissue blocks available to perform both EGFRvIII and NY-ESO-1 testing * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 or Karnofsky Performance Status (KPS) 70-100 * Age 18 years or above * Have a life expectancy of more than 12 weeks * Laboratory values (performed within 5 days) within designated range. * For women and men of childbearing potential, an acceptable method of highly effective contraception * Ability to give informed consent and comply with the protocol. Exclusion Criteria: * Have a known allergy to both penicillin and sulfa * Have artificial (prosthetic) joint(s), orthopedic screw(s), metal plate(s) or other exogenous implant(s) or device(s) that cannot be easily removed (i.e., prosthetic heart valves). * Have any evidence of hepatic cirrhosis or clinical or radiographic ascites. * Have radiographic or clinically significant pleural effusion. * Receipt of prophylactic vaccine within 28 days of study treatment. * Unable to avoid close contact with another individual known to be at high risk of listeriosis (e.g., newborn infant, pregnant woman, HIV-positive individual). * History of allergy to yeast or any other component of the ADU-623 vaccine (e.g., glycerol). * Have an immunodeficiency disease or immunocompromised state (e.g., use of immunosuppressive agents; chemotherapy or radiation therapy within 14 days of study treatment). * Have had major surgery or significant traumatic injury occurring within 28 days before treatment administration or anticipated surgery or procedure requiring general anesthesia during study participation (including 28 days after last dose of ADU-623). * Use of more than 4 grams per day of acetaminophen. * Have received an investigational product within 28 days of study treatment or planned to receive within 28 days after vaccine administration. * Have an unhealed surgical wound. * Have clinically significant heart disease (such as uncontrolled angina, myocardial infarction with the last 3 months, congestive heart failure of New York Heart Association III or IV). * Have valvular heart disease that requires antibiotic prophylaxis for prevention of endocarditis. * Have an intercurrent illness that is either life-threatening or of clinical significance such that it might limit compliance with study requirements including, but not limited to, ongoing or active infection, metabolic or neurological disease, peripheral vascular disease or psychiatric illness. * Have insufficient peripheral venous access to permit completion of the study dosing and compliance with study phlebotomy regimen. * Have received a diagnosis of HIV, HCV, or HBV (patients with hepatitis C antibody positive may be enrolled if they are confirmed with negative viral load at screening). * Have an active autoimmune disease or history of autoimmune disease requiring systemic steroids or other immunosuppressive treatment. * Other medical or psychiatric conditions that in the opinion of the Principal Investigator would preclude safe participation in protocol. * Pregnant or lactating women, as treatment has unknown effect on the embryo or child. * Patients requiring chronic corticosteroid use will be excluded as this may mask toxic effects related to the vaccine and may prevent the development of effective immune responses following vaccination.