Abstract 1162: <i>In silico</i> optimized NAMPT inhibitor for targeted delivery by antibody drug conjugates as novel therapeutic modality for treatment of liquid and solid malignancies

Abstract Background: About half of the currently FDA-approved antibody drug conjugates (ADCs) are based on microtubule inhibitors, making them effective only against actively dividing cells. Non-dividing tumor stem cells in contrast cannot be eradicated and may cause resistance and tumor relapse. Hence, there is a high demand for novel payloads with unique modes of action to overcome the current limitations. Inhibition of NAMPT, the rate-limiting enzyme in the salvage biosynthetic pathway of NAD+ starting from nicotinamide, induces cell death due to energy shortage in both dividing and non-dividing cell populations. Herein, we present encouraging in vitro and in vivo results of ADCs based on in silico designed NAMPT inhibitors (NAMPTi) as payloads, highlighting the potential of NAMPT inhibition as an emerging mode of action in ADC technology. Materials and methods: In Silico modelling: PDB published co-crystals of NAMPT with NAMPTi were used for database generation, compound enumeration, virtual screening and lead optimization of candidates in a multistep process using Schrödinger Suite. In vitro viability cell lines: L540 (CD30+); MDA-MB-453 (HER2+) ADC: The cysteine-reactive NAMPTi linker-payload constructs were synthesized at Heidelberg Pharma and conjugated to both interchain and engineered cysteine residues of anti-CD30 or anti-HER2 antibodies yielding ADCs with an average DAR of 10. Animal models: The anti-tumor efficacy of NAMPTi-based ADCs was evaluated in female NXG mice intravenously inoculated with L540 tumor cells, and female NMRI-nu mice inoculated subcutaneously with NCI-N87 tumor cells. Animals were treated with single or multiple doses of anti-CD30 and anti-HER2 ADCs, respectively. Results: Computational models allowed the discovery of unexploited features within NAMPT catalytic pocket with the potential to be used for a new generation of NAMPTi. This new generation of NAMPTi was accessed through a new in silico campaign leading to NAMPTi optimized for the use as ADC payloads, translating in excellent in vitro and in vivo anti-tumor efficacy. Single and multiple dose treatment resulted in complete remission of NCI-N87 tumors and survival of L540 disseminated tumor-bearing animals was significantly prolonged upon treatment. Conclusions: Targeted drug delivery to CD30+ and HER2+ cell lines was achieved using ADCs with in silico optimized NAMPTi linker-payloads. The use of computational approaches in the optimization of NAMPTi enabled to address unexploited features of the catalytic pocket resulting in more potent, selective and stable inhibitors, which were optimized for the targeted delivery by ADC technology. The use of anti-CD30 and HER2 ADCs loaded with NAMPTi in the therapy of CD30+ Hodgkin lymphoma and HER2+ breast cancer models, highlights this new modality as a promising approach in cancer therapy. Citation Format: Pablo Ruedas Batuecas, Hendrik Gruss, Sarah Jane Neuberth, Alexander Hempelmann, Anikó Pálfi, Marija Vranic, Andreas Pahl, Torsten Hechler. In silico optimized NAMPT inhibitor for targeted delivery by antibody drug conjugates as novel therapeutic modality for treatment of liquid and solid malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1162.