Ublituximab, a Novel, Glycoengineered Anti-CD20 Monoclonal Antibody (mAb), Demonstrates Enhanced Antibody-Dependent Cellular Cytotoxicity (ADCC) Relative to Other Anti-CD20 mAbs (P7-3.011) (2023)

<h3>Objective:</h3> In vitro functional characterization of ublituximab relative to other anti-CD20 mAbs. <h3>Background:</h3> Anti-CD20–mediated B-cell depletion is induced by several mechanisms, including ADCC and complement-dependent cytotoxicity. ADCC is independent of the complement system and is mediated by interactions between the Fc region of anti-CD20 mAbs and the Fcγ receptor (FcγR) on effector cells (eg, natural killer cells), which initiate a series of signaling pathways leading to B-cell depletion. Polymorphisms of the FcγR at amino acid 158 (F/V) can lead to impaired binding to immunoglobulin G and reduce effector-cell engagement. Ublituximab is a novel, chimeric, type 1 mAb targeting a unique epitope of CD20 on B cells. Ublituximab is glycoengineered to exclude certain sugar molecules on its Fc region, conferring greater affinity to FcγRs leading to enhanced ADCC. <h3>Design/Methods:</h3> CD20 binding, FcγRIIIa-receptor binding, and ADCC for ublituximab versus other commercially available CD20 therapies (ocrelizumab, ofatumumab, and rituximab) were evaluated in in vitro studies. CD20 binding was evaluated using a CD20-expressing cell line (Jeko-1) and a MesoScale Discovery electrochemiluminescence assay. FcγR affinity was evaluated using surface plasmon resonance. ADCC activity was evaluated using CD20-expressing Raji cells plus KILR (CD16+) effector cells and diluted human serum samples in a luminescent cytotoxicity assay. <h3>Results:</h3> All evaluated mAbs had comparable CD20-binding affinity (EC<sub>50</sub> [μg/mL): ublituximab, 0.063; ocrelizumab, 0.111; ofatumumab, 0.092; and rituximab, 0.133. Ublituximab had the highest binding affinity (K<sub>D</sub> [nM]) for FcγRIIIa 158V (64.1 versus 1025.8 [ocrelizumab], 1641.4 [ofatumumab], and 1199.8 [rituximab]) and FcγRIIIa 158F (680.3 versus 6762.9 [ocrelizumab], 14,815.2 [ofatumumab], and 6960.9 [rituximab]) as well as the highest ADCC activity (EC<sub>50</sub> [pg/mL]): 2.4 versus 60.8 (ocrelizumab), 74.1 (ofatumumab), and 5457.0 (rituximab). <h3>Conclusions:</h3> Findings from in vitro studies demonstrated that ublituximab has higher FcγR binding and ADCC activity as a result of its glycoengineered Fc region compared with other commercially available anti-CD20 mAbs. <b>Disclosure:</b> Dr. Huang has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. Dr. Huang has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. Dr. Alvarez has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Alvarez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. Dr. Alvarez has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Alvarez has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. Dr. Alvarez has received personal compensation in the range of $50,000-$99,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Alvarez has received personal compensation in the range of $50,000-$99,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Alvarez has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. Dr. Alvarez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi. Dr. Alvarez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Celgene. Dr. Alvarez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD Serono. The institution of an immediate family member of Dr. Alvarez has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB. Mr. Miskin has received personal compensation for serving as an employee of TG Therapeutics. Mr. Miskin has stock in TG Therapeutics . Dr. Lee has nothing to disclose. The institution of Dr. Foley has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Octave. Dr. Foley has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. The institution of Dr. Foley has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics . The institution of Dr. Foley has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon Therapeutics. The institution of Dr. Foley has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sandoz. Dr. Foley has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Biogen. Dr. Foley has stock in InterPRO Bioscience. The institution of Dr. Foley has received research support from Biogen. The institution of Dr. Foley has received research support from Novartis. The institution of Dr. Foley has received research support from Octave. The institution of Dr. Foley has received research support from Genentech. The institution of Dr. Foley has received research support from Imstem. The institution of Dr. Foley has received research support from Aegir.