Annexon: GA Program Strengthens C1q Platform as GBS Asset Approaches EMA Filing

What happened

Annexon’s story remains anchored in tanruprubart, a first-in-class C1q inhibitor that has shown positive phase 3 data in Guillain-Barré syndrome, supported by a cash runway into late Q1 2027 and ongoing pre-commercial groundwork. The new analysis maintains a Buy rating and highlights that Annexon is now advancing a second C1q inhibitor, vonaprument, in geographic atrophy, reinforcing the platform rather than single-asset nature of the story. Management’s plan to submit an EMA marketing application for tanruprubart in January 2026 and continue active FDA discussions aligns with the regulatory timeline outlined in recent filings. In parallel, vonaprument is in phase 3 testing for dry AMD patients with GA, with topline results from the ARCHER II trial expected in the second half of 2026, matching the company’s stated guidance. Together, these developments confirm a sequenced catalyst path across neurology and ophthalmology and support the view that current valuation does not fully reflect the dual late-stage opportunity.

Implication

For investors, the key takeaway is that Annexon remains a clinically driven, pre-commercial biotech with two late-stage C1q assets and a reaffirmed Buy view, offering multiple shots on goal rather than sole dependence on GBS. Near term, value inflection will hinge on regulatory milestones for tanruprubart—especially the planned January 2026 EMA filing and clarity on the U.S. BLA trajectory and eventual label relative to IVIG and plasmapheresis. Medium term, the ARCHER II topline in geographic atrophy in the second half of 2026 becomes a major binary event that could transform Annexon from a rare-disease neurology story into a broader ophthalmology and complement-platform name. The current cash balance and runway into late Q1 2027 reduce immediate dilution risk through these milestones, though additional capital will almost certainly be required post-2026 for launch scaling and broader pipeline development. Position sizing should therefore balance the attractive upside from two late-stage programs against execution risk in acute-care GBS logistics, competitive dynamics in GA, and the inevitability of future financing once initial catalysts play out.

Thesis delta

Our core BUY thesis—anchored in tanruprubart’s positive phase 3 data in GBS, a clear regulatory path, and a late-stage follow-on asset in GA—remains intact and fundamentally unchanged. The fresh emphasis on vonaprument as a second C1q inhibitor progressing through phase 3 in GA modestly increases our conviction in Annexon as a diversified C1q platform rather than a single-asset GBS bet, but does not alter the timing or binary nature of the H2 2026 GA readout. Overall, we see slightly improved perceived platform durability, yet the central risk/reward drivers continue to be tanruprubart’s regulatory outcomes and the ARCHER II topline data.