Targeting B-cell malignancies with the beta-emitting anti-CD37 radioimmunoconjugate (177)Lu-NNV003

PURPOSE: The aim of this study was to explore the β-emitting lutetium-177 labelled anti-CD37 antibody NNV003 ((177)Lu-NNV003, Humalutin®) for the treatment of non-Hodgkin’s lymphoma in in vitro studies and in animal models. METHODS: Cytotoxicity of (177)Lu-NNV003 was measured in REC-1 (mantle cell lymphoma) and DOHH-2 (diffuse large B cell lymphoma) cell lines. Biodistribution was studied in mice bearing subcutaneous DOHH-2 or MEC-2 (chronic lymphocytic leukaemia) xenografts. The therapeutic effect of a single injection of (177)Lu-NNV003 was measured in mice intravenously or subcutaneously injected with REC-1 cells. Haematological and histopathological assessments were used to evaluate the toxic effect of (177)Lu-NNV003. The immunotherapeutic effect of NNV003 was assessed by measuring binding to Fcγ receptors, activation of ADCC and ADCP. NNV003’s immunogenicity potential was assessed using in silico immunogenicity prediction tools. RESULTS: (177)Lu-NNV003 showed an activity dependent antiproliferative effect in all cell lines. Maximum tumour uptake in vivo was 45% of injected activity/g in MEC-2 tumours and 15% injected activity/g in DOHH-2 tumours. In mice injected intravenously with REC-1 cells, (177)Lu-NNV003 (50–100 MBq/kg) improved survival compared to control groups (p < 0.02). In mice with subcutaneous REC-1 xenografts, 500 MBq/kg (177)Lu-NNV003 extended survival compared to the control treatments (p < 0.005). Transient haematological toxicity was observed in all mice treated with radioactivity. NNV003 induced ADCC and ADCP and was predicted to have a lower immunogenicity potential than its murine counterpart. CONCLUSION: (177)Lu-NNV003 had a significant anti-tumour effect and a favourable toxicity profile. These results warrant further clinical testing in patients with CD37-expressing B cell malignancies. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00259-019-04417-1) contains supplementary material, which is available to authorized users.