Abstract LB209: An ADC composed of daratumumab and lenalidomide is extremely powerful in killing multiple myeloma cells
Authors: Yu Yueh-Hsiang , Hsieh Ming-Yu , Wu Pei-Wen , Lee Hui-Ju , Lin Pei-Hsuan , Lim Carmay , Chu Hsing-Mao , Chang Tse Wen 
Published: April 2023

Abstract
Introduction: Multiple myeloma (MM) is a neoplastic malignancy characterized by the abnormal proliferation of plasma cells with excessive antibody production in the bone marrow. It accounts for approximately 1.8% of all new cancer cases and 2.1% of cancer deaths in the United States and occurs most frequently among older adults (age &gt; 75). While there are a number of treatments with high response rates, MM relapses frequently within a few years and is considered incurable. Herein, experimental studies and results of a new therapeutic agent under development, TE-1146, are reported. TE-1146 is an antibody drug conjugate (ADC) composed of two therapeutic agents already in use in MM, namely, an anti-CD38 antibody, daratumumab (Dara), and lenalidomide (Lena).
Method: TE-1146 is designed by employing “HIDAR” technology platform, which enables the preparation of homogeneous ADCs with high DAR (drug to antibody ratio). In the TE-1146 molecules, the Fab is replaced by scFv and a cysteine-containing Zn2+-binding motif is engineered at the C-termini of the H chains. Lena molecules are assembled into drug bundles containing 3 Lena molecules and a maleimide group. Two drug bundles are conjugated site-specifically to the Zn2+-activated SH groups of the reconfigured antibody molecule, creating an ADC with DAR of 6. TE-1146 was investigated for cytolytic effects against human MM cell lines H929 in cell cultures in vitro and transplanted H929 tumor in NOD-SCID mice in vivo, in comparison with Dara, Lena, and their combination.
Results: In human plasma, TE-1146 has stability comparable with Dara, and the Lena molecules in the drug bundles remain conjugated. In cultures of H929 cells, TE-1146 caused the lysis of H929 cells at least 100 times more effectively than Dara, Lena, and Dara/Lena combination, based on IC50 comparison. It was shown that H929 cells internalized and degraded TE-1146 and freed Lena. In NOD-SCID mice, the subcutaneously transplanted H929 cells were allowed to grow into solid tumors in 14 days, and TE-1146 and other agents for comparison were administered intraperitoneally. It was found that one single dose of TE-1146 at 20 nmol/kg (conjugated with Lena at 120 nmol/kg) could retard the growth of the transplanted tumor and ultimately eliminate the tumor over 28-42 days, while the combination of one dose Dara at 20-80 nmol/kg and Lena of 46 μmol/kg given daily could not eliminate the tumor. The amount of Lena used in the combination treatment over a 28-day course is 10,700 times that of Lena in TE-1146.
Conclusion: Lenalidomide is extremely powerful in killing multiple myeloma cells if brought into the MM cells. It is estimated that a very minute amount, probably less than 0.01%, of intraperitoneally injected lenalidomide gets into the transplanted MM tumor in the mouse model. TE-1146 may be a more effective and less toxic drug than Daratumumab/Lenalidomide combination in treating patients with hard-to-treat MM.
Citation Format: Yueh-Hsiang Yu, Ming-Yu Hsieh, Pei-Wen Wu, Hui-Ju Lee, Pei-Hsuan Lin, Carmay Lim, Hsing-Mao Chu, Tse Wen Chang. An ADC composed of daratumumab and lenalidomide is extremely powerful in killing multiple myeloma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB209.