Therapeutic targets in childhood B-acute lymphoblastic leukemia: what about HER2/neu?

Camuset, Margaux; Huault, Alice; Grain, Audrey; Clémenceau, Béatrice; Rialland, Fanny; Thomas, Caroline; Chevallier, Patrice; Béné, Marie C; Eveillard, Marion

New immunotherapies based on monoclonal antibodies have recently been developed and are giving promising results in refractory B-lineage acute lymphoblastic leukemia (ALL). Indeed, CD20, CD38, CD22 and HER2/neu could constitute therapeutic targets. However, few studies have reported on the expression level of these markers. Such investigations would be useful to appreciate the potential efficacy/toxicity of immunotherapies targeting these antigens. Indeed, a cohort of 125 B-ALL patients (1-25 years old) was retrospectively enrolled, for whom the same multiparametric flow cytometry assay had been performed over the whole period, allowing for fluorescence intensities comparison. CD20, CD38 and CD22 were expressed in respectively 53,6%, 99,2% 98,4% of the cases, rather homogeneously and at intermediate levels. HER2/neu, a marker of breast cancer also expressed in a subset of ALL, was present in 16 samples (13,4%), but not detectable on hematogones. Interestingly, in this subgroup, patients had a significantly lower 5-year EFS compared to patients without expression of HER2/neu (63,0% versus 80,5%, p=0.02). In conclusion, these 4 antigens could be alternatives of interest especially since CD19 can be downmodulated after current therapies targeting this antigen. Trastuzumab could also be a potential interesting immunotherapy in the HER2/neu expressing group, especially in relapsed childhood ALL. This article is protected by copyright. All rights reserved.