NNV024, a Humanized Anti-CD37 Antibody with Enhanced ADCC and Extended Plasma Half-Life for the Treatment of B-Cell Malignancies

Background: There is a significant unmet clinical need for new therapeutic approaches for patients with B-cell non-Hodgkin lymphomas (B-NHL) who relapse or are refractory to anti-CD20 therapies. Moreover, certain B-cell malignancies do not express CD20. High expression of the CD37 antigen on malignant B-cells associated with limited or no expression on other hematopoietic cells makes CD37 a highly attractive alternative target for B-cell depleting therapies. We have therefore developed a humanized anti-CD37 monoclonal antibody (NNV024) engineered to exhibit a strong antibody-dependent cellular cytotoxicity (ADCC).

Methods: Generation of NNV024 was performed by combining in silico CDR-grafting and structure-based back mutation. Candidates were then selected for their affinity to CD37 expressing cell line, Ramos. In silico immunogenicity prediction tools were integrated in the selection process to support the generation of a candidate with low immunogenicity potential (NNV023). Last, to increase ADCC, the selected candidate was afucosylated at the N-linked bi-antennary glycan at N297 of the Fc region (NNV024).

The NNV024 was characterized in vitro and in vivo. Binding to human Fc gamma receptors (FcγRs), neonatal Fc receptor (FcRn), and complement component 1q (C1q) was confirmed by ELISA and SPR. ADCC and antibody-dependent cellular phagocytosis (ADCP) induction were measured using cell-based reporter assays with eleven cell lines derived from B-NHL subtypes such as Burkitt's lymphoma, diffuse large B-Cell lymphoma (DLBCL), and mantel cell lymphoma (MCL). All cell lines express both CD20 and CD37 on their cell surface. In addition, B cell chronic lymphocytic leukaemia (B-CLL) cells isolated from patient samples were used to test induction of ADCC, ADCP and complement-dependent cytotoxicity (CDC) in vitro. NNV024 plasma pharmacokinetics were assessed in Tg32 transgenic mice expressing human FcRn, which is considered a key regulator of IgG plasma half-life. A therapy study comparing NNV024 (n=10) and obinutuzumab (n=10) was performed using a disseminated tumor (Daudi) model in CB17-SCID mice (10⁷ cells/mouse, i.v.). The anti-CD20 Abs rituximab and obinutuzumab as well as the anti-CD37 Ab, Duohexabody-CD37, were used for benchmarking.

Results: As expected, the glyco-engineering increased affinity of NNV024 to FcγRIIIa (K_D before afucosylation: 460.8 ng/mL; K_D after: 104.1 ng/mL). Binding of Abs to FcγRIIIa activates immunological effector cells such as Natural Killer cells, macrophages, monocytes, and eosinophils. NNV024 demonstrated ADCC superior to that observed with obinutuzumab, rituximab, and Duohexabody-CD37. NNV024 exhibited a 2-fold prolonged plasma half-life in mice (8.9±0.8 days) compared to obinutuzumab (4.4±1.3 days) and Duohexabody-CD37 (4.1±1.2 days). Mice survival was enhanced up to ~ 40% when treated with NNV024 (10 µg/mouse - 70.5 days; 50 µg/mouse - 84 days) compared to obinutuzumab at a dose of 10 µg (70.5 days vs. 53 days) or 50 µg (84 days vs. 62 days).

Conclusion: These encouraging preclinical results support further development of NNV024 as a potential therapeutic mAb candidate for the treatment of B-cell malignancies and B-cell driven autoimmune disorders.

Generalov:Nordic Nanovector ASA: Current Employment, Current holder of stock options in a privately-held company. Fiorito:Nordic Nanovector ASA: Current Employment, Current holder of stock options in a privately-held company. Pascal:Veronique Pascal: Current Employment, Current equity holder in publicly-traded company, Current holder of stock options in a privately-held company. Heyerdahl:Nordic Nanovector ASA: Current Employment, Current equity holder in publicly-traded company. Repetto-Llamazares:Nordic Nanovector ASA: Current Employment, Current equity holder in publicly-traded company, Current holder of stock options in a privately-held company. Andersen:Authera AS: Other: Co-founder; Argenx: Other: Funding as part of fee-for-service agreement , Research Funding. Skånland:TG Therapeutics: Research Funding; BeiGene: Research Funding; Abbvie: Honoraria; AstraZeneca: Honoraria. Dahle:Nordic Nanovector ASA: Current Employment, Current equity holder in publicly-traded company, Current holder of stock options in a privately-held company.