Inclusion Criteria:

        -Patients must have histologically confirmed diagnosis of a recurrent/progressive WHO grade
        IV malignant gliomas (glioblastoma multiforme and gliosarcoma) and meet the following
        inclusion criteria:

          1. Age ≥18 years of age.

          2. Histologic diagnosis of glioblastoma or gliosarcoma (WHO Grade IV).

          3. KPS of ≥ 70%.

          4. Life expectancy > 12 weeks.

          5. First or second relapse of glioblastoma.

          6. Previous treatment for glioblastoma must include surgery (biopsy, partial resection,
             or full surgical resection), conventional radiation therapy and temozolomide (TMZ).

          7. MRI record must be obtained showing the MRI was conducted at least 4 weeks after any
             salvage surgery, and at least 12 weeks after radiation therapy, or at least 4 weeks
             after radiation for a new lesion outside the prior primary radiation field unless
             relapse is confirmed by tumor biopsy or new lesion outside of radiation field, or if
             there are two MRIs confirming progressive disease per iRANO that are 8 weeks apart

          8. If prior therapy with gamma knife or other focal high-dose radiation, must have
             subsequent histologic documentation of local relapse, or relapse with new lesion
             outside the irradiated field.

          9. Resolution of all chemotherapy or radiation-related toxicities ≤ CTCAE Grade 1
             severity, except for alopecia and hematologic toxicity. Patients taking temozolomide
             can start study treatment 23 days from the last temozolamide dose.For all other
             chemotherapy drugs, study treatment can start as long as all adverse events related to
             their prior treatment are no higher than Grade 1.

         10. Systemic corticosteroid therapy must be at a dose of ≤ 4 mg of dexamethasone or
             equivalent per day during the week prior to Day 1.

         11. Pre-surgical Bi-dimensionally measurable disease (as per iRANO criteria)

         12. Patients must have normal organ and marrow function as defined below:

               -  hemoglobin (Hbg) > 9g/dL,

               -  leukocytes >1,500/mcL

               -  absolute neutrophil count>1,000/mcL

               -  CD4 count > 450/mcL

               -  platelets>125,000/mcL

               -  Serum bilirubin = 1.5 × upper limit of normal (ULN) or = 3 x ULN if Gilbert's
                  disease is documented AST(SGOT) and ALT(SGPT)<2.5 X institutional upper limit of
                  normal

               -  serum creatinine < 1.5 mg/dl

         13. Signed informed consent approved by the Institutional Review Board;

         14. If sexually active, patients must agree to take contraceptive measures for the
             duration of the treatments.

        Exclusion Criteria:

          1. Subjects unable to undergo an MRI with contrast.

          2. Presence of diffuse leptomeningeal disease

          3. History, presence, or suspicion of metastatic disease

          4. Administration of immunosuppressive drugs less than 2 weeks prior to first dose of
             ERC1671, except dexamethasone for cerebral edema as detailed above;

          5. Prior receipt of bevacizumab, or bevacizumab biosimilars or other VEGF- or VEGF
             receptor-targeted agents

          6. Known contraindication or hypersensitivity to any component of bevacizumab.

          7. Evidence of recent hemorrhage on screening MRI of the brain with the following
             exceptions: presence of hemosiderin; resolving hemorrhagic changes related to surgery;
             presence of punctate hemorrhage in the tumor.

          8. Significant vascular disease (e.g., aortic aneurysm, aortic dissection) or recent
             peripheral arterial thrombosis within 6 months prior to Day 1.

          9. Evidence of bleeding diathesis or coagulopathy as documented by an elevated PT, PTT or
             bleeding time and clinically significant;

         10. History of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess
             within 6 months prior to Day 1.

         11. Urine protein: creatinine ratio ≥ 1.0 at screening;

         12. Anticipation of need for major surgical procedure during the course of the study.

         13. Serious non-healing wound, ulcer, or bone fracture.

         14. Active infection requiring treatment, known immunosuppressive disease, active systemic
             autoimmune diseases such as lupus, receipt of systemic immunosuppressive therapy,
             human immunodeficiency virus (HIV) infection, Hepatitis B or Hepatitis C

         15. Uncontrolled hypertension, blood pressure of > 150 mmHg systolic and > 100 mmHg
             diastolic, or history of hypertensive encephalopathy. Subjects with any known
             uncontrolled inter-current illness including ongoing or active infection, symptomatic
             congestive heart failure (NYHA Gr.2 or >), myocardial infarction, unstable angina
             pectoris , within the past 12 months

         16. Stroke, transient ischemic attack, unstable angina, myocardial infarction or
             congestive heart failure (New York Heart Association Grade II or greater) within the
             past 6 months.Unstable or severe intercurrent medical conditions chronic renal
             disease, or uncontrolled diabetes mellitus.

         17. Women who are pregnant or lactating. All female patients with reproductive potential
             must have a negative pregnancy test prior to Day 1 and must use a reliable form of
             contraception during study participation.

         18. Men refusing to exercise a reliable form of contraception.

         19. History of any malignancy (other than glioblastoma) during the last three years except
             non-melanoma skin cancer, in situ cervical cancer, treated superficial bladder cancer
             or cured, early-stage prostate cancer in a patient with Prostate Surface Antigen (PSA)
             level <ULN.