Authors’ Reply: “On the Importance of Considering Glycosylation when Evaluating Biologic Therapies” : Journal of the American Society of Nephrology

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Letter to the Editor

Authors’ Reply: “On the Importance of Considering Glycosylation when Evaluating Biologic Therapies”

Angeletti, Andrea1,3; Ravani, Pietro2; Bruschi, Maurizio3; Ghiggeri, Gian Marco1,3

Author Information
JASN 33(8):p 1626, August 2022. | DOI: 10.1681/ASN.2022050534

We thank Dr. Lemaire for the interest in our work and for the relevant observations.

He reported that anti-CD20 mAbs, due to their generation in Golgi animal cell lines, may bring the sialic acid N-glycolylneuraminic (Neu5Gc), activated via linkage to cytidine monophosphate (CMP) by the enzyme cytidine monophosphate N-acetylneuraminic acid hydroxylase (Cmah), to be added to the terminal of glycans by sialyl transferases. In humans, the activated Neu5Gc is not present due to the deletion of the CMAH gene. In addition, exposure to animal proteins may have stimulated amplification of anti-Neu5Gc.1 Moreover, rituximab and ofatumumab are produced in CHO (Chinese hamster ovary) and NS0 (murine myeloma) cells, respectively. NSO express higher Cmah than CHO, with consequent significantly higher immunogenic profile of ofatmumab than rituximab.

The immunogenicity of fully human anti-CD20 mAbs is not often considered in clinical practice but is relevant because it may affect efficacy. Further studies might address possible relevance of meat-heavy Western diets.2

We hypothesized that ofatumumab would be more effective than rituximab in a cohort of patients with steroid-dependent nephrotic syndrome on the basis of the stronger binding with CD20 and higher activation of complement that Lemaire reports. We observed equivalence between the two anti-CD20 mAbs,3 with rituximab superior in subjects aged <9 years.3 We also observed that previous exposure to rituximab results in production of anti-rituximab antibodies, which persists for a limited time but does not affect response to further administration.

Lemaire posits that anti-Neu5GC antibodies may limit ofatumumab efficacy. Therefore, stratification of subjects enrolled in the ofatumumab arm, on the basis of the presence of circulating anti-Neu5Gc antibodies, may affect the results of our clinical trial.

A goal of our present research is development of techniques to detect anti-Neu5Gc antibodies. The application will be extended to other ongoing studies with second-generation anti-CD20 mAbs.

The introduction of anti-CD20 mAbs in 20114 has revolutionized the therapeutic approach to idiopathic nephrotic syndrome in children and to primary and secondary autoimmune glomerulonephritis in adults, such as membranous nephropathy and glomerulonephritis secondary to ANCA-vasculitis.

It is fundamental to confirm the hypothesis in our large cohort and to determine how long circulating anti-Neu5Gc antibodies persist. Detection of anti-Neu5Gc antibodies prior to and during treatment with chimeric, human, or humanized anti-CD20 mAbs would promote a more personalized therapeutic approach.


All authors have nothing to disclose.


P. Ravani and G.M. Ghiggeri were supported by the Italian Ministry of Health, Ricerca Finalizzata (Grant: WFR: PE/Number: 2016-02361576).

Published online ahead of print. Publication date available at

See related letter to the editor, “On the Importance of Considering Glycosylation when Evaluating Biologic Therapies,” on page , and original article, “Human or Chimeric Monoclonal Anti-CD20 Antibodies for Children with Nephrotic Syndrome: A Superiority Randomized Controlled Trial,” in Vol. 32, Iss. 10, on pages .

Author Contributions

A. Angeletti and G.M. Ghiggeri were responsible for conceptualization and wrote the original draft of the manuscript; M. Bruschi was responsible for data curation; and all authors reviewed and edited the manuscript.


1. Varki A: Colloquium paper: Uniquely human evolution of sialic acid genetics and biology. Proc Natl Acad Sci U S A 107: 8939–8946, 2010
2. Samraj AN, Pearce OM, Läubli H, Crittenden AN, Bergfeld AK, Banda K, et al.: A red meat-derived glycan promotes inflammation and cancer progression. Proc Natl Acad Sci U S A 112: 542–547, 2015
3. Ravani P, Colucci M, Bruschi M, Vivarelli M, Cioni M, DiDonato A, et al.: Human or chimeric monoclonal anti-CD20 antibodies for children with nephrotic syndrome: A superiority randomized trial. J Am Soc Nephrol 32: 2652–2663, 2021
4. Ravani P, Magnasco A, Edefonti A, Murer L, Rossi R, Ghio L, et al.: Short-term effects of rituximab in children with steroid- and calcineurin-dependent nephrotic syndrome: A randomized controlled trial. Clin J Am Soc Nephrol 6: 1308–1315, 2011

rituximab; idiopathic nephrotic syndrome; membranous nephropathy; anti-CD20 antibodies; focal segmental glomerulosclerosis; glomerulonephritis; obinutuzumab; vasculitis; pediatric nephrology

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