EXTH-78. WP1874, A HIGHLY POTENT UNIQUE DNA BINDING AGENT WITH ENHANCED CNS UPTAKE

As part of our drug discovery program, we have developed structure-based modular designs of unique DNA-binding agents. The approach combines DNA intercalating and DNA “minor-groove-binding” modules. We have discovered compound WP1244 that potentially binds up to 10 bp long sequences of DNA. The unique and intriguing feature of WP1244 is its high CNS uptake combined with the picomolar to low nanomolar cytotoxicity against ependymoma and glioblastoma multiforme (GBM) cell lines and demonstrated in vivo activity in the orthotopic model of GBM. To improve water solubility and develop an IV formulation, we have synthesized WP1874, a mesylate salt of WP1244, and initiated its preclinical characterization. WP1874, similarly to its parental compound, shows high cytotoxicity in ependymoma, GBM, and medulloblastoma cell lines with IC50 in low nanomolar range and it was up to 100 to 200 times more potent than doxorubicin. Interestingly, WP1874 does not appear to be cytotoxic against normal kidney cells (VeroC1008) with IC50 > 10 μM. Preliminary pharmacokinetic and biodistribution studies performed in CD-1 mice with intact brains revealed enhanced penetration of WP1874 to the brain with Cmax 1.5-fold greater than in plasma. Respectively, WP1874 Cmax in the brain was 2.3 ug/g (~2.0 μM) vs. 1.5 μg/ml (1.3 μM) in plasma. Acute toxicity in intravenously administered WP1874 was LD50 >15mg/kg. No mortalities or any apparent toxicity symptoms were recorded for six intravenous weekly doses of WP1874 at 2.5 or 5 mg/kg in CD-1, Balb/c, or nude athymic mice. Intraperitoneal administration was well-tolerated up to 5 mg/kg given three times a week for four cycles. High CNS uptake, excellent cytotoxicity against different brain cancer cell lines, and low toxicity in vivo and in vitro against normal cells warrant further investigation of WP1874 as a mechanically unique potential anticancer agent against CNS malignancies.