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Most read from mAbs

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The Antibody Society is pleased and proud to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue. All the articles are open access; PDFs can be downloaded by following the links below.

Issue 10.8 (November/December 2018)

Rapid, automated characterization of disulfide bond scrambling and IgG2 isoform determination. In this new report, Resemann et al. discuss a rapid LC-MALDI-TOF/TOF workflow that can both identify the IgG2 disulfide linkages and provide a semi-quantitative assessment of the distribution of the disulfide isoforms. They established signature disulfide-bonded IgG2 hinge peptides that correspond to the A, A/B, and B disulfide isoforms, and can be applied to the fast classification of IgG2 isoforms in heterogeneous mixtures.

Charge variant native mass spectrometry benefits mass precision and dynamic range of monoclonal antibody intact mass analysis. Bailey et al. describe charge variant native mass spectrometry (CVMS), an integrated native ion exchange mass spectrometry-based charge variant analytical approach that delivers detailed molecular information in a single, semi-automated analysis. They used pure volatile salt mobile phases over a pH gradient that effectively separated variants based on minimal differences in isoelectric point. Characterization of variants such as deamidation, which are traditionally unattainable by intact mass due to their minimal molecular weight differences, were measured unambiguously by mass and retention time to allow confident MS1 identification. The authors demonstrated that efficient chromatographic separation allows introduction of the purified forms of the charge variant isoforms into the Orbitrap mass spectrometer. Based on their results, they conclude that the CVMS method allows confident assignment of intact monoclonal antibody isoforms of similar mass and relative abundance measurements across three orders of magnitude dynamic range.

A systematic approach for analysis and characterization of mispairing in bispecific antibodies with asymmetric architecture. In this new report, Wang et al. discuss a systematic approach for analysis and characterization of mispairing in asymmetric bispecific antibodies. This approach consists of three orthogonal components, the first of which is a liquid chromatography (LC)-mass spectrometry (MS)–based method to measure the mass of intact antibodies. This method is used for fast analysis of mispairing and requires minimal method development, which makes it an ideal choice for early-stage development. The second component is a hydrophobic interaction chromatography (HIC)–based mispairing method that is suitable for lot release testing. The HIC method is robust and quality control friendly, and offers great linearity, precision, and accuracy. The third component is a two-dimensional LC-MS method for on-line chromatographic peak identification, which not only expedites this task but also reduces the risk of undesirable modifications during conventional fraction collection. These three methods dovetail to form the foundation of a complementary toolbox for analysis and characterization of mispairing in asymmetric bispecific antibodies and provide guidance and support for process development throughout the drug development life cycle.

Characterization and analysis of scFv-IgG bispecific antibody size variants. Cao et al. report size variants that were observed for an appended scFv-IgG bispecific antibody. Structural characterization studies showed that the size variants resulted from the engineered disulfide bond on the scFv, whereby the engineered disulfide was found to be either open or unable to form an intrachain disulfide bond due to cysteinylation or glutathionylation of the cysteines. Furthermore, the scFv engineered cysteines also formed intermolecular disulfide bonds, leading to the formation of highly stable dimers and aggregates. Because both the monomer variants and dimers showed lower bioactivity, they were considered to be product-related impurities that must be monitored and controlled. To this end, the authors developed and optimized a robust, precise, and accurate high-resolution size-exclusion chromatographic method, using a statistical design-of-experiments methodology.

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First approval for emapalumab

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On November 20, 2018, the US Food and Drug Administration approved emapalumab (Gamifant) for the treatment of pediatric (newborn and above) and adult patients with primary hemophagocytic lymphohistiocytosis (HLH) who have refractory, recurrent or progressive disease or intolerance with conventional HLH therapy. Developed by NovImmune SA, emapalumab is a human IgG1 antibody that targets interferon gamma. Emapalumab has received a variety of designations intended to facilitate the development of drugs for rare, serious or life-threatening diseases, including Breakthrough Therapy, Rare Pediatric Disease, and Orphan Drug designations in the US, and Priority Medicines and Orphan Drug designations in the EU. The FDA’s approval was based in part on a clinical study of 27 pediatric patients with suspected or confirmed primary HLH with either refractory, recurrent or progressive disease during conventional HLH therapy or who were intolerant of conventional HLH therapy. Results from this study showed that 63% of patients experienced a response and 70% were able to proceed to stem cell transplant. A marketing application for emapalumab is undergoing evaluation by the European Medicines Agency.

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Most read from mAbs issue 10.7

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The Antibody Society is pleased and proud to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue. All the articles are open access; PDFs can be downloaded by following the links below.

MAbs Issue 10.7 (October 2018)

Platform development for expression and purification of stable isotope labeled monoclonal antibodies in Escherichia coli.  In this report, Reddy et al. present the expression and purification of a stable isotope labeled mAb from a genetically engineered E. coli strain capable of forming disulfide bonds in its cytoplasm. Using 2D NMR spectral fingerprinting, they show that the unlabeled mAb and the mAb singly or triply labeled with 13C, 15N, 2H are well folded, with only minor structural differences relative to the mammalian cell-produced mAb that are attributed to the lack of glycosylation in the Fc domain.

Massive parallel screening of phage libraries for the generation of repertoires of human immunomodulatory monoclonal antibodies. Sasso et al discuss a novel approach for the generation of several novel human immunomodulatory antibodies capable of binding their targets in their native conformation and useful for therapeutic applications. They performed a massive parallel screening of phage libraries by using activated human lymphocytes to generate large collections of scFvs against 10 immune checkpoints: LAG-3, PD-L1, PD-1, TIM3, BTLA, TIGIT, OX40, 4-1BB, CD27 and ICOS. By next-generation sequencing and bioinformatics analysis, they ranked individual scFvs in each collection and identified those with the highest level of enrichment. Human IgGs from three of these collections (i.e., PD-1, PD-L1 and LAG-3) were generated and shown to have comparable or better binding affinity and biological activity than clinically validated mAbs. The repertoires generated in this work represent a convenient source of agonistic or antagonistic antibodies against the ‘Checkpoint Immunome’ for preclinical screening and clinical implementation of optimized treatments.

High-throughput screening of antibody variants for chemical stability: identification of deamidation-resistant mutants. In this report, DiCara et al describe a high-throughput method for antibody stability screening during the early stages of antibody discovery and highlight the value of broad searches of antibody sequence space. They developed a high-throughput assay to characterize asparagine deamidation and used it to identify a mutation that unexpectedly stabilizes a critical asparagine. Ninety antibody variants were incubated under thermal stress in order to induce deamidation and screened for both affinity and total binding capacity. Surprisingly, a mutation five residues downstream from the unstable asparagine greatly reduced deamidation.

Extending human IgG half-life using structure-guided design. Booth et al. report on the development of a structure- and network-based framework to interrogate the engagement of IgG with multiple Fc receptors (FcRn, C1q, TRIM21, FcγRI, FcγRIIa/b, FcγRIIIa) simultaneously. They identified features that govern Fc-FcRn interactions and identified multiple distinct pathways for enhancing FcRn binding in a pH-specific manner. Network analysis provided a novel lens to study the allosteric impact of half-life-enhancing Fc mutations on FcγR engagement, which occurs distal to the FcRn binding site. Applying these principles, they engineered a panel of unique Fc variants that enhance FcRn binding while maintaining robust biophysical properties and wild type-like binding to activating receptors.

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We encourage you to join the Society to take advantage of the substantial benefits of membership, including discounts on fees for selected KNect365, CHI, and Hanson Wade meetings, discounted subscriptions to Society-affiliated journals PEDS and mAbs (special subscription rate of US $84 online only access for Antibody Society members)  and access to information in the Members Only section of the website. In particular, we encourage members to take advantage of the discount on registration for Antibody Engineering & Therapeutics, which is the annual meeting of The Antibody Society traditionally held in San Diego in December. Membership is free for students, post-docs and employees of our corporate sponsors!

First approval for cemiplimab-rwlc

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On September 28, 2018, the U.S. Food and Drug Administration (FDA) approved cemiplimab-rwlc (Libtayo) for the treatment of patients with metastatic cutaneous squamous cell carcinoma (CSCC) or locally advanced CSCC who are not candidates for curative surgery or curative radiation. Cemiplimab-rwlc is the third antibody therapeutic targeting PD1 to be granted an FDA approval, but it is the first drug to be approved in the US specifically for advanced CSCC.

FDA’s approval of Libtayo was based on a combined analysis of data from an open-label, multi-center, non-randomized Phase 2 trial known as EMPOWER-CSCC-1 (Study 1540) and two advanced CSCC expansion cohorts from a multi-center, open-label, non-randomized Phase 1 trial (Study 1423). A total of 108 patients (75 with metastatic disease and 33 with locally-advanced disease) were included in the efficacy evaluation. The confirmed objective response rate for all patients treated with Libtayo was 47%. FDA granted cemiplimab Breakthrough Therapy Designation status for advanced CSCC in 2017, and the drug’s marketing application was granted a priority review.

The Antibody Society maintains a comprehensive table of approved mAb therapeutics and those in regulatory review in the EU or US. As of Sep 28, a total of 11 antibody therapeutics had been granted first approvals in either the US or EU in 2018, and marketing applications for another 5 that have not yet been approved in either the EU or US are undergoing review in these regions. Please log in to access the table in either PDF or Excel formats, located in the Members Only section.

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First approval for galcanezumab-gnlm

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On September 27, 2018, the U.S. Food and Drug Administration (FDA) approved galcanezumab-gnlm (Emgality) for the preventive treatment of migraine in adults. Emgality is the third antibody therapeutic approved by FDA in 2018 for this indication. As we reported in previous posts, Aimovig (erenumab-aooe) was approved on May 17, 2018 and Ajovy (fremanezumab-vfrm) was approved on September 14, 2018. The three products target either calcitonin gene-related peptide (CGRP) or the CGRP receptor. The recommended dosage of Emgality is 240 mg loading dose (administered as two consecutive injections of 120 mg each), followed by monthly doses of 120 mg.

The efficacy and safety of Emgality was demonstrated in two Phase 3 clinical trials in patients with episodic migraine (EVOLVE-1, EVOLVE-2) and one Phase 3 clinical trial in patients with chronic migraine (REGAIN). In all three studies, patients were randomized to receive once-monthly placebo, Emgality 120 mg after an initial loading dose of 240 mg, or Emgality 240 mg. In EVOLVE-1, the mean change from baseline (days) was -4.7 days (N=210) for Emgality 120 mg compared to -2.8 days (N=425) for placebo (p<0.001), while in EVOLVE-2, the mean change from baseline (days)was -4.3 days (N=226) for Emgality 120 mg compared to -2.3 days (N=450) for placebo (p<0.001). In the REGAIN study, the mean change from baseline (days) was -4.8 days (N=273) for Emgality 120 mg compared to -2.7 days (N=538) for placebo (p<0.001).

The Antibody Society maintains a comprehensive table of approved mAb therapeutics and those in regulatory review in the EU or US. As of Sep 28, a total of 10 antibody therapeutics had been granted first approvals in either the US or EU in 2018, and marketing applications for another 6 that have not yet been approved in either the EU or US are undergoing review in these regions. Please log in to access the table in either PDF or Excel formats, located in the Members Only section.

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