ME-344

ME-344 is a novel drug candidate that inhibits mitochondrial oxidative phosphorylation (OXPHOS), a fundamental metabolic pathway involved in the production of adenosine triphosphate (ATP) in the mitochondria. ATP provides energy to drive many metabolic cell processes, including division, proliferation, and growth. By disrupting the production of ATP, ME-344 has been shown to induce cancer cell death in nonclinical models and was associated with antitumor activity in clinical studies.

The two main sources of ATP production in cells are OXPHOS and glycolysis; the latter is highly active in most tumors. Anti-angiogenics, like the vascular endothelial growth factor (VEGF) inhibitor bevacizumab (AVASTIN®), have the potential to normalize vasculature and decrease reliance on glycolysis. The resulting reduction in glycolysis may trigger an increased dependence on mitochondrial ATP production for energy to support continued tumor proliferation.

In such cases of tumor plasticity, the combination of ME-344 and bevacizumab may induce metabolic synthetic lethality, providing a novel therapeutic strategy. Specifically, leveraging the ability of antiangiogenics like bevacizumab to reduce glycolysis and force tumor cells to switch to mitochondrial respiration via OXPHOS, which is inhibited by ME-344, may reduce access to ATP needed for cell division and growth in tumors.

This approach was first clinically evaluated in a multicenter, investigator-initiated, randomized, open-label, window of opportunity clinical study, evaluating ME-344 (3 doses) plus bevacizumab (1 dose) in 42 women with early HER2-negative breast cancer. Study results demonstrated significant biological antitumor activity as measured by a reduction in the proliferative biomarker Ki-67 compared to placebo. The combination appeared to be generally well tolerated. The data from this study were consistent with preclinical data suggesting that combining ME-344 can augment anti-angiogenic therapy and provided validation for continued evaluation of the combination of ME-344 with bevacizumab and other VEGF inhibitors.

An earlier Phase 1 clinical study evaluating ME-344 as a single-agent in patients with refractory solid tumors also demonstrated anti-tumor activity, further validating the potential of mitochondrial inhibition as a promising therapeutic modality.

We are advancing ME-344 in combination with the anti-angiogenic antibody bevacizumab (Avastin®) in an ongoing Phase 1b study evaluating patients with relapsed metastatic colorectal cancer. The study is evaluating patients with progressive disease after failure of standard therapies. Patients are being administered ME-344 until disease progression or intolerance. The primary objective is progression free survival. Secondary endpoints include overall response rate, duration of response, overall survival, and safety.

ME-344 was previously evaluated in multiple clinical studies, including a multicenter, randomized, open-label, clinical trial that evaluated the combination of ME-344 and bevacizumab an anti-angiogenic therapy, in 42 women with early HER2-negative breast cancer. Results the study were published in the November 2019 issue of Clinical Cancer Research.

The primary objective of the trial was to show proof of ME-344 biologic activity as measured by reductions in the nuclear protein Ki67 (expression of which is strongly associated with tumor cell proliferation and growth) compared to the control group who received bevacizumab plus placebo. Secondary objectives included determining whether ME-344 biologic activity correlates with vascular normalization. The data demonstrate significant biologic activity in the ME-344 treatment group:

• In ME-344 treated patients, mean absolute Ki67 decrease was 13.3 compared to an increase of 1.1 in the bevacizumab monotherapy group (P=0.01).
• In ME-344 treated patients, mean relative Ki67 decrease was 23% compared to an increase of 186% in the bevacizumab monotherapy group (P < 0.01).

Treatment was generally well tolerated; three grade 3 adverse events of high blood pressure were reported, two in the ME-344 arm and one in the bevacizumab monotherapy arm.

Results from our earlier, first-in-human, single-agent Phase 1 clinical trial of ME-344 in patients with refractory solid tumors were published in the April 1, 2015 issue of Cancer. The results indicated that eight of 21 evaluable patients (38%) treated with ME-344 achieved stable disease or better, including five who experienced progression-free survival that was at least twice the duration of their last prior treatment before entry into the trial. In addition, one of these patients, a heavily pre-treated patient with small cell lung cancer, achieved a confirmed partial response and remained on study for two years. ME-344 was generally well tolerated at doses equal to or less than 10 mg/kg delivered on a weekly schedule for extended durations. Treatment-related adverse events included nausea, dizziness and fatigue. Dose-limiting toxicities were observed at both the 15 mg/kg and 20 mg/kg dose levels, consisting primarily of grade 3 peripheral neuropathy.

ME-344 has been evaluated in patients with solid tumors, which represent the most common type of cancer. Most solid tumors are carcinomas, which usually begin in the skin or the surface of internal organs and glands.

ME-344 is being evaluated in combination with bevacizumab, (marketed as Avastin®) in a Phase 1b study in patients with previously treated metastatic colorectal cancer.