Case Study | Engineering Stabilization of a CD52-Targeting Monoclonal Antibody Against Deamidation

Alemtuzumab is a humanized anti-CD52 monoclonal antibody developed by Genzyme and approved in 2001 for the treatment of chronic lymphocytic leukemia (CLL). Genzyme was later acquired outright by Sanofi for $20.1 billion, and this drug became part of Sanofi’s portfolio. In addition to alemtuzumab, Sanofi subsequently developed a second-generation anti-CD52 monoclonal antibody—Gatralimab, the subject of this case study. Unfortunately, Gatralimab was discontinued and removed from Sanofi’s development pipeline. 01 Problem Identification Asparagine deamidation is a critical post-translational modification in antibodies that can significantly affect protein structure and function. During developability assessment of the unmodified Gatralimab molecule, researchers identified N33G in the light-chain CDR1 as a deamidation hotspot; this modification markedly impaired molecular affinity. Under accelerated conditions, the molecule was incubated in buffers of varying pH. Over time, the extent of deamidation at N33G in the light-chain CDR1 increased progressively—and higher pH further accelerated this deamidation. Surface plasmon resonance (SPR) assays confirmed that deamidated molecules exhibited significantly reduced binding affinity. To further confirm the functional impact of N33 deamidation in the light-chain CDR1, researchers engineered an N33D mutant. Functional evaluation revealed that this mutant’s binding activity was ~400-fold lower than that of the wild-type molecule. 02 Structural Analysis of Antigen–Antibody Interaction To gain deeper insight into the structural basis of antigen–antibody interaction, researchers performed X-ray crystallography. The heavy-chain CDR1 and CDR3, along with the light-chain CDR1 and CDR2, all participated in antigen binding. Specifically, the light-chain CDR1 formed two direct interactions with the phosphate group of the CD52 peptide antigen: (i) hydrogen bonding between N33 and a phospho-oxygen atom, and (ii) ionic interaction between K35 and another phospho-oxygen atom. This structural analysis explains why the N33D mutation nearly abolished binding affinity: substitution with aspartic acid introduces electrostatic repulsion. Another key finding from the structural analysis was that G34 lies outside the interaction interface—making it a more suitable candidate for mutagenesis without disrupting antigen binding. 03 Engineering Optimization Having identified N33 as the deamidation hotspot—and having structurally confirmed its critical role—researchers initiated engineering efforts. Although G34 appeared more amenable to mutation (as noted above), the root cause remained N33; thus, initial attempts focused on modifying N33 itself. N33 substitutions were designed either conservatively (e.g., N33Q) or to preserve the hydrogen bond observed in the crystal structure between N33 and the antigen. High-throughput screening revealed that all N33 variants—including the conservative N33Q substitution and the sequence-reversed KGN mutant—led to substantial losses in antigen-binding affinity.

SAMR Extends Antitrust Review of Kimberly-Clark’s Acquisition of Kenvue | Kimberly-Clark May Divest Kenvue’s Feminine Care Business in New Zealand

Recently, multiple media outlets and self-media accounts reported on the State Administration for Market Regulation’s (SAMR) extension of the antitrust review of Kimberly-Clark’s acquisition of Kenvue. Some reports referenced the author’s submission of feedback comments to SAMR, for example: ・ Chinese regulators reviewing Kimberly-Clark’s $49-billion acquisition deal ・ Is a >¥300-billion household products merger stalled? ・ A ¥300-billion merger faces regulatory hurdles in China, adding uncertainty to the global consumer goods landscape Since June 2014, the author has submitted over 150 feedback comments—covering at least 150 simplified merger filings—on cases reviewed under China’s simplified procedure for concentration of undertakings. In some instances, supplementary comments were also submitted. However, in most cases, the author received neither follow-up phone calls nor emails from SAMR’s antitrust enforcement officers. Related discussions include: ・ SAMR approved Jiangxi Fangda Iron and Steel Group’s acquisition of equity in five subsidiaries of Desheng Group on May 20, 2026—but the approval was not publicly announced until June 8, while Fangda Group issued a stock trading volatility announcement on June 3. ・ Alleged failure to respond to third-party feedback: Approval on March 13, 2026, of the joint venture formation between Shenzhen Bao’an District Industrial Investment Guidance Fund… and Shenzhen Saimi Industrial Private Equity Investment Fund… ・ Alleged failure to respond to third-party feedback: Unconditional approval on March 10, 2026, of Shiheng Special Steel Group Co., Ltd.’s acquisition of equity in twenty-two companies, including Shandong Tai Shan Iron and Steel Group Co., Ltd. However, on June 2, 2026, the author did receive a telephone call from antitrust enforcement officers at the Shaanxi Provincial Administration for Market Regulation. The approximately 17-minute conversation concerned the feedback comments the author had submitted to SAMR’s Antitrust Enforcement Division II on May 17, 2026, regarding Kimberly-Clark’s proposed acquisition of Kenvue. ・ Feedback on Simplified Merger Filing: Kimberly-Clark Corporation’s Acquisition of Kenvue Inc. During the call, the author reiterated concerns previously raised in the written feedback—particularly regarding market definition and the reliability of reported market share data—and additionally proposed using complementary economic indicators to holistically assess the market influence of merging parties. Over the past nearly 18 years of merger review practice in China, antitrust enforcement authorities have never explicitly required merging parties to disclose the sources of their market share data. Consequently, external stakeholders often cannot ascertain whether the filing party may have colluded with third-party market research firms to artificially manipulate market share figures. Moreover, because China’s merger review process incurs no filing fees, antitrust enforcement agencies face practical constraints in procuring independent, third-party market research data—or in commissioning third-party verification of the authenticity and methodological rigor of data submitted by filing parties—for every case. As of June 11, 2026, SAMR has never publicly initiated investigations or imposed penalties on filing parties suspected of submitting false or misleading information in simplified merger filings. Related discussions include: ・ What legal consequences may arise from fraudulent submissions in simplified merger filings? Unlike traditional industrial sectors—where authoritative production and output data are readily obtainable from industry regulators or associations—in digital economy and consumer goods sectors, complex pricing mechanisms and high price volatility make market share calculations based on turnover particularly susceptible to discrepancies across different institutions, due to variations in statistical methodology.

EU Approves Kimberly-Clark's Acquisition of Kenvue Subject to Conditions

15 hours ago

The European Commission approved Kimberly-Clark's acquisition of Kenvue after concessions addressed antitrust concerns. Kimberly-Clark will divest feminine hygiene brands including Kotex in the European Economic Area.

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EU Approves Kimberly-Clark's Acquisition of Kenvue Subject to Conditions

EU Approves Kimberly-Clark's Acquisition of Kenvue Subject to Conditions

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