LOR-253 is an anticancer small molecule that is currently in a Phase I clinical study in patients with advanced or metastatic solid tumors. LOR-253 has a novel anticancer mechanism based on chelation of intracellular labile zinc, leading to inhibition of angiogenesis as well as G1/S cell cycle arrest due to induction of the tumor suppressor Kruppel-like factor 4 (KLF4). In preclinical studies, LOR-253 has shown potent antitumor activity against several cancers, including non-small cell lung cancer (NSCLC) and colon cancer, without significant toxicity. To support the clinical development of LOR-253 in combination with chemotherapeutics, we investigated the effect of dose scheduling of LOR-253 plus chemotherapy agents on anticancer activity in NSCLC (H226) and colon cancer (SW620) cell lines. Treatment of H226 cells in vitro with docetaxel, paclitaxel, or cisplatin for two days followed by increasing doses of LOR-253 resulted in significantly higher anti-proliferative activity than either agent alone. Assessment of drug interactions by determination of the combination index (D) (Berenbaum MC, Adv Cancer Res., 1981; 35:269-335) showed that the anticancer activities of the combination of LOR-253 with these chemotherapy agents were synergistic (D < 1). In studies with LOR-253 and docetaxel, synergistic anticancer activity against H226 was maintained with either concurrent or sequential treatments of each agent. Anticancer synergy was also seen in SW620 cells treated with LOR-253 in combination with oxaliplatin, CPT-11, or Fluorouracil. The effects of dose scheduling on activity of LOR-253 and docetaxel in vivo was also examined. Nude mice with H226 tumor xenografts were treated with repeat cycles of docetaxel once per week, followed two days later by treatment with LOR-253 for three consecutive days. Docetaxel was administered at an experimentally-determined ED50 dose level (defined as the effective dose at which 50% of mice showed tumor growth inhibition), while LOR-253 was given at its maximum efficacious dose in this model (10 mg/kg) or sub-optimal dose (5 mg/kg). Sequential administration of docetaxel followed by LOR-253 showed significant antitumor activity when docetaxel was given at either ED50 or sub-ED50 doses plus 10 mg/kg of LOR-253, compared to either agent alone given at the same dose, or with concurrent administration of LOR-253 and docetaxel at these dose levels. Preliminary results also show significant antitumor activity of LOR-253 plus docetaxel against H226 tumors in mice treated with repeat cycles of the reverse order of these treatments (LOR-253 for three days, followed by docetaxel 1X/week). In summary, dose scheduling studies with LOR-253 plus chemotherapy drugs demonstrate strong anticancer activities in NSCLC and colon cancer, providing support for the design of LOR-253 combination strategies for treatment of these cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3710. doi:1538-7445.AM2012-3710