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T-cell assays confirm immunogenicity of tungsten-induced erythropoietin aggregates associated with pure red cell aplasia

Tina Rubic-Schneider, Masataka Kuwana, Brigitte Christen, Manuela Aßenmacher, Otmar Hainzl, Frank Zimmermann, Robert Fischer, Vera Koppenburg, Salah-Dine Chibout, Timothy M. Wright, Andreas Seidl and Michael Kammüller

Key Points

  • Tungsten-induced rhEPO aggregates in clinical lots are associated with rhEPO-neutralizing antibodies and PRCA.

  • T-cell responses differentiate nonaggregated from aggregated rhEPO, confirming immunogenicity of tungsten-induced rhEPO aggregates.

Abstract

Immunogenicity of biotherapeutics and the elicitation of anti-drug antibodies are a key concern for their efficacy, pharmacokinetics, and safety. A particularly severe consequence of immunogenicity of a biotherapeutic is the rare development of antibody-mediated pure red cell aplasia (PRCA) in anemic patients treated with aggregated forms of recombinant human erythropoietin (rhEPO). Here, we investigated in vitro T-cell responses to experimentally heat-induced rhEPO aggregates, and to tungsten-induced rhEPO aggregates in clinical lots associated with rhEPO-neutralizing antibodies and PRCA. Heat-stressed rhEPO elicited T-cell responses only in blood obtained from healthy individuals identified as responders, whereas nonstressed rhEPO overall did not induce reactions neither in responders nor nonresponders. Tungsten-induced rhEPO aggregates in clinical lots associated with rhEPO-neutralizing antibodies and PRCA could induce in vitro T-cell responses in blood obtained from healthy donors, in contrast to rhEPO from low tungsten syringes. Importantly, ex vivo T-cell recall responses of patients treated with rhEPO without PRCA showed no T-cell responses, whereas T cells of a patient who developed PRCA after treatment with a clinical batch with elevated levels of tungsten and rhEPO aggregates showed a clear response to rhEPO from that clinical batch. To our knowledge, this is the first time that T-cell assays confirm the root cause of increased rhEPO immunogenicity associated with PRCA.

  • Submitted October 3, 2016.
  • Accepted January 6, 2017.
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