Laboratory findings in patients treated with complement factor C3 inhibitor pegcetacoplan

Area of Science:

• Complement biology
• Immunology
• Nephrology

Background:

• Pegcetacoplan, a C3 and C3b inhibitor, is approved for paroxysmal nocturnal hemoglobinuria (PNH).
• Its efficacy is explored in C3 glomerulopathy due to complement dysregulation.
• Pegcetacoplan induces counterintuitive laboratory alterations.

Purpose of the Study:

• To analyze complement system changes in patients treated with pegcetacoplan.
• To understand the implications of pegcetacoplan therapy on laboratory diagnostics.

Main Methods:

• In-depth complement analysis was performed on patients with PNH and C3 glomerulopathy undergoing pegcetacoplan treatment.
• Laboratory findings were correlated with in vitro experiments and mass spectrometry.

Main Results:

• Pegcetacoplan treatment led to a 300% increase in C3 levels, attributed to increased C3 half-life, not assay artifact.
• A three-fold increase in properdin and an additional C3-band on serum protein electrophoresis were observed.
• Pegcetacoplan effectively inhibited the alternative complement pathway while largely sparing the classical pathway.

Conclusions:

• Clinicians and laboratory specialists must be aware of pegcetacoplan-induced laboratory findings.
• Understanding these changes is crucial for accurate patient management in clinical practice.