ORIGINAL RESEARCH ARTICLE published: 08 November 2012 doi: 10.3389/fonc.2012.00160
Preclinical evaluation of racotumomab, an anti-idiotype monoclonal antibody to N-glycolyl-containing gangliosides, with or without chemotherapy in a mouse model of non-small cell lung cancer Valeria I. Segatori 1 , Ana M. Vazquez 2 , Daniel E. Gomez 1 , Mariano R. Gabri 1 and Daniel F. Alonso 1* 1 2
Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Buenos Aires, Argentina Center of Molecular Immunology, Innovation Managing Direction, La Habana, Cuba
Edited by: Amparo Macías, Center of Molecular Immunology, Cuba Reviewed by: Sebastien Calbo, A*Star, Singapore Jianping Huang, NCI/NIH, USA *Correspondence: Daniel F. Alonso, Laboratorio de Oncología Molecular, Universidad Nacional de Quilmes, R. Sáenz Peña 352, Bernal, B1876BXD Buenos Aires, Argentina. e-mail: dfalonso@unq.edu.ar
N-glycolylneuraminic acid (NeuGc) is a sialic acid molecule usually found in mammalian cells as terminal constituents of different membrane glycoconjugates such as gangliosides. The NeuGcGM3 ganglioside has been described as a tumor antigen for non-small cell lung cancer (NSCLC) in humans. Racotumomab is an anti-NeuGc-containing gangliosides anti-idiotype monoclonal antibody (mAb) (formerly known as 1E10) that has received attention as a potential active immunotherapy for advanced lung cancer in clinical trials. In this work, we have examined the antitumor activity of racotumomab in combination or not with chemotherapy, using the 3LL Lewis lung carcinoma as a preclinical model of NSCLC in C57BL/6 mice. Vaccination with biweekly doses of racotumomab at 50–200 μg/dose formulated in aluminum hydroxide (racotumomab-alum vaccine) demonstrated a significant antitumor effect against the progression of lung tumor nodules. Racotumomab-alum vaccination exerted a comparable effect on lung disease to that of pemetrexed-based chemotherapy (100 mg/kg weekly). Interestingly, chemo-immunotherapy was highly effective against lung nodules and well-tolerated, although no significant synergistic effect was observed as compared to each treatment alone in the present model. We also obtained evidence on the role of the exogenous incorporation of NeuGc in the metastatic potential of 3LL cells. Our preclinical data provide support for the combination of chemotherapy with the anti-idiotype mAb racotumomab, and also reinforce the biological significance of NeuGc in lung cancer. Keywords: cancer immunotherapy, anti-idiotype antibody, N-glycolylneuraminic acid, NSCLC, mouse models
INTRODUCTION N-glycolylneuraminic acid (NeuGc) is a sialic acid molecule usually found in mammalian cells as terminal constituents of different membrane glycoconjugates such as the GM3 ganglioside (NeuGcGM3). Gangliosides are a broad family of glycosphingolipids found on the outer cell membrane, involved in cell communication, regulation of the immune response, and cancer progression (Patra, 2008; Lopez and Schnaar, 2009). NeuGcGM3 has been described as a tumor antigen for non-small cell lung cancer (NSCLC) in humans (van Cruijsen et al., 2009; Blanco et al., 2012). The significance of NeuGc overexpression in human cancer is still under investigation. Considering that anti-NeuGc antibodies can be detected in several cancer patients, it was hypothesized that antibody-mediated inflammation could facilitate tumor progression (Varki, 2010). However, it is widely accepted that high titers of these antibodies can induce tumor cell death (Roque Navarro et al., 2008; Varki, 2010; Hernandez et al., 2011). In addition, experimental data indicated that growth-stimulating features of NeuGc on tumor cells can be explained by immune system down-modulation (De Leon et al., 2008).
www.frontiersin.org
Racotumomab is an anti-NeuGc-containing gangliosides antiidiotype monoclonal antibody (mAb), formerly known as 1E10, that has received attention as a potential active immunotherapy for advanced lung cancer in clinical trials (Neninger et al., 2007; Alfonso et al., 2008). As an anti-idiotype antibody, racotumomab is the mirror image of the P3 mAb idiotype which specifically reacts against NeuGc antigens on cell surface (Vazquez et al., 1998). Previously, we evaluated the antitumor activity of racotumomab in syngeneic mouse tumor models. Vaccination with several biweekly intraperitoneal doses of racotumomab coupled to keyhole limpet hemocyanin in Freund’s adjuvant, significantly inhibited the formation of spontaneous lung metastases by F3II mammary carcinoma cells (Vazquez et al., 2000). Administration of low-dose cyclophosphamide together with subcutaneous immunization with aluminum hydroxide-precipitated racotumomab (racotumomab-alum vaccine) significantly reduced F3II primary tumor growth. The antitumor response was comparable to that obtained with standard high-dose chemotherapy in such breast cancer model, but without overt signs of toxicity. Interestingly, combinatory chemo-immunotherapy promoted CD8+ lymphocyte tumor infiltration and increased tumor
November 2012 | Volume 2 | Article 160 | 1