Strategia Therapeutics, Inc.

C4 (cobalt dichloride-N-acetylcysteine [1% CoCl2:2% NAC]) is a novel magnetic resonance imaging contrast marker that facilitates visualization of implanted radioactive seeds in cancer brachytherapy. We evaluated the toxicity of C4. Rats were assigned to control (0% CoCl2:NAC), low-dose (0.1% CoCl2:2% NAC), reference-dose (C4), and high-dose (10% CoCl2:2% NAC) groups. Agent was injected into the left quadriceps femoris muscle of the rats. Endpoints were organ and body weights, hematology, and serum chemistry and histopathologic changes of tissues at 48 hours and 28 and 63 days after dosing. Student’s t tests were used. No abnormalities in clinical signs, terminal body and organ weights, or hematologic and serum chemistry were noted, and no gross or histopathologic lesions of systemic tissue toxicity were found in any treatment group at any time point studied. At the site of injection, concentration-dependent acute responses were observed in all treatment groups at 48 hours after dosing and were recovered by 28 days. No myofiber degeneration or necrosis was observed at 28 or 63 days in any group. In conclusion, a single intramuscular dose of C4 produced no acute or chronic systemic toxicity or inflammation in rats, suggesting that C4 may be toxicologically safe for clinical use in cancer brachytherapy.

The novel positive-contrast magnetic resonance imaging (MRI) marker C4 consists of an aqueous solution of cobalt chloride (CoCl2) complexed with the chelator N-acetylcysteine (NAC). We evaluated whether the presence of C4 or its components would produce reactive oxygen species (ROS, including hydroxyl, peroxyl, or other reactive oxygen species) in cultured cells. Human cancer or normal cells were incubated with 1% (w/v) CoCl2·6H2O or 2% NAC or a combination of both (1% CoCl2·6H2O : 2% NAC in an aqueous solution, abbreviated as Co : NAC) in the presence or absence of H2O2. Intracellular ROS levels were measured and quantified by change in relative fluorescence units. Student’st-tests were used. In all cell lines exposed to 1000 μM H2O2, the Co : NAC led to ≥94.7% suppression of ROS at 5 minutes and completely suppressed ROS at 60 and 90 minutes; NAC suppressed ROS by ≥76.6% at 5 minutes and by ≥94.5% at 90 minutes; and CoCl2·6H2O suppressed ROS by ≥37.2% at 30 minutes and by ≥48.6% at 90 minutes. These results demonstrate that neither Co : NAC nor its components generated ROS; rather, they suppressed ROS production in cultured cells, suggesting that C4 would not enhance ROS production in clinical use.

FF-10501-01 is a selective inosine monophosphate dehydrogenase (IMPDH) inhibitor that has shown activity in cancer cell lines. We studied whether FF-10501-01 is effective in targeting a variety of hypomethylating agent (HMA)-sensitive and -resistant acute myelogenous leukemia (AML) cell lines.

We treated multiple cell lines (including HMA-resistant cells) with FF-10501-01 and analyzed proliferation, apoptosis, and cell cycle status. We also assessed HMA-FF-10501-01 combinations and the ability of extracellular guanosine to rescue cell proliferation in FF-10501-01-treated cells. We performed high-performance liquid chromatography (HPLC) to study guanine nucleotide levels in treated and untreated cells. Finally, we studied the effects of FF-10501-01 in fresh peripheral blood cells taken from AML patients.

FF-10501-01 showed a strong dose-dependent effect on proliferation and induced apoptosis at approximately 30μM. The effects of FF-10501-01 treatment on cell cycle status were variable, with no statistically significant trends. Guanosine rescued proliferation in FF-10501-01-treated cells, and HPLC results showed significant decreases in phosphorylated guanosine levels in MOLM13 cells. FF-10501-01 effectively reduced proliferation at concentrations of 300μM and above in 3 primary AML samples.

FF-10501-01 effectively induces AML cell death and reduces AML peripheral blood cell proliferation by targeting guanine nucleotide biosynthesis regardless of HMA resistance status.