Abstract CT116: Phase I/II study of dianhydrogalactitol (VAL-083) with radiation therapy in patients with newly diagnosed, MGMT-unmethylated glioblastoma

Abstract

Glioblastoma (GBM) is the most common and aggressive primary brain cancer. Current standard-of-care includes surgery followed by chemo-radiation and temozolomide. An unmethylated promoter for O6-methylguanine-DNA-methyltransferase (MGMT) is a validated biomarker for temozolomide-resistance and is strongly correlated with poor outcomes. Unmethylated MGMT represents the majority of newly diagnosed GBM tumors. VAL-083 is a first-in-class bi-functional DNA-targeting agent that has shown activity against GBM in NCI-sponsored clinical trials both as single agent and in combination with radiotherapy. VAL-083 induces interstrand cross-links at N7-guanine, leading to DNA double-strand breaks and cell-death. VAL-083’s unique mechanism-of-action circumvents MGMT-mediated chemoresistance, and it has demonstrated cytotoxicity in MGMT-unmethylated GBM cell-lines, cancer stem cells (CSCs) and in vivo models. Furthermore, VAL-083 acts as a radiosensitizer in GBM CSCs and non-CSCs. We completed a dose-escalation trial of VAL-083 in recurrent GBM, and a generally well-tolerated dosing regimen was selected for further clinical development. The present trial is an ongoing open-label, biomarker-driven, Phase I/II study to evaluate the tolerability and efficacy of VAL-083 in combination with radiotherapy in newly diagnosed MGMT-unmethylated GBM patients. A treatment regimen, consisting of a 6-week induction period of VAL-083 and concurrent radiation (2 Gy daily, 5 days/week) followed by up to 24 weeks of maintenance therapy with single-agent VAL-083, is being evaluated. The study is being conducted in two parts. The dose-confirmation part (20, 30, and 40 mg/m2/day IV infusion on days 1-3 of a 21-day cycle) has been completed, and the expansion part has been initiated in up to 20 additional patients at 30 mg/m2/day IV infusion on days 1-3 of a 21-day cycle. Tumor response will be assessed by MRI, according to RANO criteria. Efficacy endpoints include progression-free survival (PFS) and overall survival (OS). Additional endpoints include safety evaluations and pharmacokinetic assessments of plasma and CSF samples. Trial design, enrollment and safety data update will be provided at the meeting. Clinicaltrials.gov identifier: NCT03050736. Citation Format: Zhong-ping Chen, Chengcheng Guo, Jeffrey Bacha, John Langlands, Anne Steino, Claire Kwan, Sarath Kanekal, Richard Schwartz, Lorena Lopez, Dennis Brown. Phase I/II study of dianhydrogalactitol (VAL-083) with radiation therapy in patients with newly diagnosed, MGMT-unmethylated glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT116.

Dianhydrogalactitol synergizes with topoisomerase poisons to overcome DNA repair activity in tumor cells

“…Moreover, MMR deficiency is also reported to mediate platinum-resistance in the treatment of many other malignant diseases, such as lung, bladder, colorectal, and ovarian cancers 49 . Previous studies have demonstrated that DAG treatment is effective in both MGMT positive and negative GBM cells, suggesting that DAG may be able to circumvent MGMT-mediated TMZ resistance 6 . Eukaryotic cells contain several proteins responsible for the MMR activity, among which MLH1 and MSH2 proteins are the key components for different heterodimers (MLH1-PMS2, MLH1-PMS1, MLH1-MLH3; MSH2-MSH6, MSH2-MSH3) that dictate substrate specificity and cellular function 50 – 53 .…”

“…It is a small water-soluble agent that readily crosses blood–brain-barrier 5 . Recently, DAG has been tested and shown activity either alone or in combination with radiation therapy in GBM clinical trials 6 . However, a detailed understanding of DAG cytotoxicity and cellular survival mechanisms is needed in order to further improve the outcomes of GBM therapeutic strategies in clinic.…”