DB107-Retroviral Replicating Vector (RRV) Combined With DB107-Flucytosine (FC) in Patients With Recurrent Glioblastoma or Anaplastic Astrocytoma

This study is testing a two-part experimental treatment for recurrent high-grade brain tumors (glioblastoma or anaplastic astrocytoma). The approach uses a specially engineered virus injected into the tumor during surgery, followed by an antifungal drug (flucytosine) that converts into a cancer-killing agent inside the tumor cells. **You may be eligible if...** - You are between 18 and 75 years old - Your brain tumor (glioblastoma or anaplastic astrocytoma) has come back after initial treatment - Your tumor is visible and measurable on an MRI scan - You have completed your last chemotherapy treatment at least 4 weeks ago - You have received prior radiation therapy **You may NOT be eligible if...** - You have certain serious infections (e.g., HIV, hepatitis B or C) - You are pregnant - You have other active cancers - Your overall health is too poor to tolerate surgery Talk to your doctor to see if this trial is right for you.