Gefurulimab (ALXN1720): A Comprehensive Clinical and Pharmacological Profile of a Novel Bispecific Nanobody for Generalized Myasthenia Gravis

Executive Summary

Gefurulimab, also identified by its development code ALXN1720, is an investigational, humanized bispecific VHH antibody, or "nanobody," engineered by Alexion, AstraZeneca Rare Disease.[1] It represents a third-generation therapeutic agent within the complement C5 inhibitor class, specifically developed for the treatment of adults with anti-acetylcholine receptor (AChR) antibody-positive (Ab+) generalized myasthenia gravis (gMG).[4] The molecular architecture of gefurulimab is a testament to advanced bioengineering, conferring a dual-action mechanism. One functional domain potently binds to and inhibits the terminal complement protein C5, thereby blocking the pivotal inflammatory pathway implicated in the pathophysiology of gMG. A second, distinct domain binds to serum albumin, a strategic design element intended to significantly extend the drug's circulatory half-life and support a convenient dosing schedule.[1]

The primary differentiating feature of gefurulimab is its patient-centric design, enabled by its unique molecular properties. Its relatively low molecular weight allows for a high-concentration formulation suitable for low-volume, subcutaneous (SC) self-administration on a once-weekly basis.[1] This positions gefurulimab as a potentially more convenient and less burdensome alternative to existing intravenous C5 inhibitors, which require administration in a clinical setting.