Abstract 4572: The CD30/CD16A RECRUIT TandAb AFM13 activates patient NK cells resulting in specific tumor cell killing.
Authors: Rothe Achim , Topp Max S. , Younes Anas , Reusch Uwe , Knackmuss Stefan , Rajkovic Erich , Eichenauer Dennis A. , Hummel Horst , Reiners Katrin S. , Dietlein Markus , Kessler Joerg , Ravic Miroslav , Hucke Christian , Zhukovsky Eugene , Pogge von Strandmann Elke , Engert Andreas 
Published: August 2014

Abstract
AFM13 represents a new class of bispecific antibodies, based on the RECRUIT-TandAb platform, which enables the generation of therapeutics with improved efficacy, convenient administration regimens, and excellent safety profiles. AFM13 was developed for the treatment of Hodgkin Lymphoma (HL) and other CD30+ malignancies. AFM13 targets CD30 on HL tumor cells and recruits NK cells via CD16A. Preclinical data demonstrate specific and highly efficient anti-tumor activity by the selectively recruited NK cell immune response, which addresses key deficiencies of monoclonal antibodies: (i) reduced binding to the 158F allotype of CD16A and (ii) non-selective binding to immune effector cells via both activating CD16A and non-signalling CD16B receptors. In vitro assays demonstrate that AFM13 binds with high affinity to both CD30 and CD16A antigens and rapidly induces lysis of CD30+ cells at picomolar concentrations. Further, AFM13 activates CD16A only in the presence of tumor cells: there is no systemic activation of NK-cells in the absence of target cells. A robust GMP process in mammalian cells and a lyophilized formulation with excellent stability are established. Finally, no toxicity is observed in Cynomolgus monkeys. AFM13 was investigated in an open-label single-arm phase I dose escalation trial in heavily pre-treated patients with relapsed/refractory HL. Each patient received 4 weekly doses of AFM13. Seven dose levels from 0.01 to 7.0 mg/kg were escalated in cohorts of 3 patients. In addition, one cohort of 4 patients received AFM13 twice a week at 4.5 mg/kg for 4 weeks. All dose levels of AFM13 proved to be well tolerated and safe and clear signs of anti-tumor activity were demonstrated. We have performed an analysis of the activation of NK cells and clearance of soluble CD30 in humans since these are key parameters for the mode of action of AFM13. We confirmed a correlation between anti-tumor activity parameters and biomarkers based on a statistically significant dose-dependent increase in the activation of NK cells and reduction in soluble CD30 levels. Since the activation of NK cells has been reported to facilitate low-level expression of CD30 on NK cells, which we also observed in several patients in the highest AFM13 dose groups, we investigated whether this may affect NK cell cytotoxicity. Our ex vivo evaluation of samples from patients that received AFM13 and in vitro evaluation of activated NK cells demonstrated no inhibition of NK cell-mediated cytotoxic activity. Furthermore, AFM13 exhibits a remarkable half-life of 1 day which represents a substantial increase relative to that of diabody-like formats currently being evaluated in the clinic for haematological malignancies. Thus, AFM13 has demonstrated encouraging biologic activity and represents a new targeted therapy for heavily pre-treated patients with HL.
Citation Format: Achim Rothe, Max S. Topp, Anas Younes, Uwe Reusch, Stefan Knackmuss, Erich Rajkovic, Dennis A. Eichenauer, Horst Hummel, Katrin S. Reiners, Markus Dietlein, Joerg Kessler, Miroslav Ravic, Christian Hucke, Eugene Zhukovsky, Elke Pogge von Strandmann, Andreas Engert. The CD30/CD16A RECRUIT TandAb AFM13 activates patient NK cells resulting in specific tumor cell killing. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4572. doi:10.1158/1538-7445.AM2013-4572