Characterization of the Antibody Response against NeuGcGM3 Ganglioside Elicited in Non-Small Cell Lung Cancer Patients Immunized with an Anti-Idiotype Antibody

Abstract

1E10 mAb is an anti-Id murine mAb (Ab2 mAb) specific for an Ab1 mAb that reacts with NeuGc-containing gangliosides, sulfatides, and Ags expressed in some human tumors. In preclinical studies, this Ab2 Ab was able to mimic NeuGc-containing gangliosides only in animals lacking expression of these Ags in normal tissues. In this study, we report on the immune responses elicited in 20 non-small cell lung cancer patients treated with 1 mg of aluminum hydroxide-precipitated 1E10 mAb. In the hyperimmune sera from 16 of 20 patients, a strong specific Ab response of both IgM and IgG isotypes against NeuGcGM3 ganglioside was observed. Patient immune sera were able to induce complement-independent cell death of NeuGcGM3-expressing X63 murine myeloma target cells. Significant immunoreactivity to NeuGcGM3 was still detected after the complete abrogation of the reactivity against 1E10 mAb by the adsorption of patient sera with this Ab. We hypothesize that Id−Ag+ Abs could reflect the activation of an autologous idiotypic cascade into the patients. Both Id+Ag+ and Id−Ag+ fractions were separated by affinity chromatography and characterized. Although IgG isotype Abs were found in both fractions, IgM isotype Abs were found only in the Id−Ag+ fraction. Both Id+Ag+ and Id−Ag+ Abs were able to specifically recognize and induce cell death in NeuGcGM3-expressing X63 myeloma target cells. Patients that developed IgG and/or IgM Abs against NeuGcGM3 showed longer median survival times.

A Randomized, Multicenter, Placebo-Controlled Clinical Trial of Racotumomab-Alum Vaccine as Switch Maintenance Therapy in Advanced Non–Small Cell Lung Cancer Patients

“…Our group has previously reported the induction of an antibody response against NeuGcGM3 ganglioside in patients with breast, melanoma, SCLC, and NSCLC treated with the racotumomab-alum vaccine (28,29,32,33). In the present study, we confirmed the immunogenicity of this anti-idiotype vaccine.…”

“…The lytic capacity of patients' sera was tested by incubating the 1:5 diluted sera with 10 5 tumor cells in DMEM/F12 medium supplemented with 1% FBS in 5% CO 2 atmosphere at 37 C, for 3 hours (33,39,41). Cell death percent was determined by flow cytometry after the addition of propidium iodide (PI; Sigma-Aldrich) at a final concentration of 10 mg/mL.…”

“…Patients' hyperimmune sera were able to specifically recognize and induce cell death of the NeuGcGM3-expressing X63 myeloma cells. Remarkably, patients who developed IgM or IgG antibodies against NeuGcGM3 showed longer median survival time (33).…”

Lonely killers

“…[58][59][60][61]63 A positive correlation between the development of such antibodies and patient survival was found. 63 Despite the lack of direct cytotoxicity by P3 mAb, 66 the antibodies generated by the anti-idiotypic vaccine were able to directly kill GM3(Neu5Gc)-expressing cells. 91 Furthermore, these antibodies induced a 14F7-like type of cell death, including the formation of the membrane lesions on target cells, even at 4°C.…”

“…GM3(Neu5Gc) is a ganglioside whose expression has been detected in some human tumors, including breast and melanoma. 53,55,56 Several therapeutic strategies have been developed against this target, 14 e.g., vaccines (ganglioside-based 57 and antiidiotypic [58][59][60][61][62][63] ) and mAbs. 55 14F7 mAb is specific for this ganglioside and unable to bind its N-acetylated (Neu5Ac) counterpart.…”