CTNI-71. RELA FUSION-POSITIVE EPENDYMOMA, DIFFUSE MIDLINE GLIOMA AND GRADE 4 IDH MUTANT ASTROCYTOMA TREATED WITH VAL-083 UNDER EXPANDED ACCESS: CASE REPORTS

Abstract RELA fusion-positive ependymoma is associated with supratentorial location, higher WHO grade and poor prognosis. Diffuse Midline Glioma (DMG) is a relatively rare CNS tumor, originating in the midline location of the brain. Surgical intervention is restricted to biopsy and radiation. Grade-4 astrocytoma, is highly aggressive with rapid progression. Standard treatment includes surgery and radiation therapy, with limited systemic options other than clinical trials for recurrent disease. VAL-083 is a DNA-targeting agent which rapidly induces inter-strand DNA cross-links at O6- and N7-guanine inducing double-strand breaks causing cell death and acts independent of MGMT DNA repair in high-grade gliomas. We report on 4 patients who had recent disease progression and unmethylated MGMT promoter status treated with VAL-083 under an expanded access program: Case #1: a 47-yo male diagnosed with IDHwt, RELA fusion-positive ependymoma. Case #2: an 18-yo male diagnosed with IDHwt, MAP2K1 and RELA fusion-positive ependymoma. Case #3: a 25-yo male diagnosed with IDHmut Grade 4 astrocytoma, with ATRX, INPP4A, RET and TP53 mutations. Case #4: a 21 yo male diagnosed with IDHwt DMG of the brain stem. All patients had multiple recurrences, received radiation and multiple systemic treatment regimens. They received VAL-083 (30 mg/m2 for 3 days every 21 days) under an expanded access program. Patients with ependymoma received 6 and 5 cycles of VAL-083, (case 1 and 2, respectively), while the patients with IDHmut Gr 4. astrocytoma and DMG received 5 and 18 cycles of VAL-083, respectively. No adverse events were reported and no dose reductions were required. These cases highlight that VAL-83 may be a treatment option for recurrent RELA fusion-positive ependymoma, Gr4. IDHmut astrocytoma, and DMG refractory to other treatment regimens. Additional outcomes related to these cases will be presented at the meeting. Clinicaltrials.gov Identifier: NCT03138629. The treatment plans for the EA patients were approved by MD Anderson Cancer Center IRB