Abstract 339: Development of a lung cancer model to evaluate the MoA of L-BLP25.

Abstract

Abstract Introduction. L-BLP25 is an antigen-specific cancer immunotherapeutic agent targeting human mucin 1 (hMUC1), which has shown promise in a phase II clinical trial for patients with non-small cell lung cancer. Appropriate animal models are required to dissect the efficacy and immune activity of long-term treatment with L-BLP25. Here we describe a novel, long-term, carcinogen-induced lung adenoma model in hMUC1 transgenic (hMUC1.Tg) mice, which results in multiple tumor foci expressing hMUC1. The immunomodulatory effect of a single low- or high- dose of cyclophosphamide (CPA) on L-BLP25-induced immunity was examined in this model. Methods. To establish the most effective method of carcinogenesis, tumor incidence was assessed in hMUC1.Tg mice receiving vehicle control, carcinogen urethane only (0.75 mg/kg, i.p. 10 times weekly), urethane + 7 mg/kg diethylstilbestrol (DES), or urethane + 14 mg/kg DES (8 times weekly, s.c., starting from week 4 of urethane treatment). A group of WT mice received urethane alone. Vehicle control, low- (100 mg/kg) and high- (300 mg/kg) dose of CPA was administered to urethane-treated groups. L-BLP25 (10 μg) was administered s.c., 8 times weekly, either alone or with low-dose CPA. The treatment groups comprised 6-21 mice. Serum Th1 and Th2 cytokines were quantified by Luminex assay in urethane only-treated hMUC1.Tg mice. Serum Th1, Th2 and inflammatory cytokines were quantified in groups treated with L-BLP25 and CPA. Results. Tumor incidence rates were 0% for vehicle control, 100% (hMUC1.Tg mice) and 80% (WT mice) in urethane only groups and 50% (DES 7 mg/kg) and 66.7% (14 mg/kg DES) in urethane + DES groups, establishing urethane alone as sufficient for inducing lung tumors with multiple foci in hMUC1.Tg mice. hMUC1+ tumors were observed in 100% of hMUC1.Tg mice vs. 0% of WT mice. Immunohistology revealed normal hMUC1 tissue expression in transgenics. Urethane dosing during tumorigenesis in the absence of treatment had no consistent effect upon serum Th1/Th2 cytokines, while it induced a consistent peak in inflammatory cytokines. Low-dose, but not high-dose, CPA reduced the incidence of urethane-induced tumors in MUC1.Tg mice compared to control (p>0.05). Low-dose CPA did not cause a shift towards a Th1 cytokine profile compared to high-dose CPA. Compared to L-BLP25 alone, low-dose CPA given prior to L-BLP25 induced Th1 cytokine IL-12 (p<0.0001) and IL-2 and IFNγ (non-significant) at 24 h after the 8th L-BLP25 dose. Th2 cytokines were elevated to a lesser extent and some inflammatory cytokines were increased. Conclusions. Urethane is sufficient to induce hMUC1-expressing lung tumors with multiple foci in hMUC1.Tg mice, without skewing the Th1/Th2 cytokine profile. When given as a low pretreatment dose, CPA potentiates the Th1 cytokine response to L-BLP25, which might contribute to the reduction of the observed incidence of urethane-induced tumors. Citation Format: Michael W. DeGregorio, Gregory T. Wurz, Audrey M. Gutierrez, Daniel P. Vang, Brittany E. Greenberg, Stephen M. Griffey, Michael Wolf. Development of a lung cancer model to evaluate the MoA of L-BLP25. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 339. doi:10.1158/1538-7445.AM2013-339