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Annexon, Inc.

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Business Summary

Annexon, Inc. is a clinical-stage biopharmaceutical company focused on developing targeted immunotherapies for complement-mediated neuroinflammatory diseases, which affect approximately 10 million people worldwide. The company's core business model revolves around its proprietary platform designed to inhibit the classical complement pathway by targeting C1q, the pathway's initiating molecule. This approach aims to suppress excessive or aberrant classical complement activity to slow or halt disease progression while preserving beneficial immune functions of other complement pathways. The company generates revenue through the sale of equity securities and warrants, as it currently has no products approved for commercial sale and has incurred significant losses since its inception in March 2011.

The company's pipeline includes three flagship programs: tanruprubart, vonaprument, and ANX1502. Tanruprubart is an investigational targeted immunotherapy for Guillain-Barré Syndrome (GBS), an acute, rare neuromuscular emergency affecting approximately 150,000 people annually worldwide . In a placebo-controlled Phase 3 trial, approximately 90% of GBS patients treated with tanruprubart improved by week 1, and more than twice as many treated patients achieved a normal state of health at week 26. The company filed a Marketing Authorization Application (MAA) with the European Medicines Agency (EMA) for tanruprubart in GBS in January 2026. Vonaprument is an investigational neuroprotective inhibitor of C1q for dry Age-related Macular Degeneration (AMD) with Geographic Atrophy (GA), a leading cause of blindness affecting over eight million people worldwide . In the Phase 2 ARCHER trial, vonaprument reduced the risk of 15-letter vision loss by more than 70%. Enrollment of 659 patients in the global Phase 3 ARCHER II trial was completed in July 2025. ANX1502 is a novel oral small molecule inhibiting the activated form of C1s, an enzyme that initiates the classical cascade, and is being evaluated in an ongoing proof-of-concept (POC) study in patients with cold agglutinin disease (CAD).

For the fiscal year ended December 31, 2025, Annexon reported a net loss of $206.7 million , compared to a net loss of $138.2 million for the year ended December 31, 2024. The accumulated deficit as of December 31, 2025, was $917.4 million . Total operating expenses increased by $62.3 million , or 40% , from $154.1 million in 2024 to $216.4 million in 2025. Research and development expenses, a significant portion of operating expenses, increased by $65.3 million , or 55% , to $184.7 million in 2025 from $119.4 million in 2024. General and administrative expenses decreased by $2.9 million , or 8% , to $31.7 million in 2025 from $34.6 million in 2024. Interest and other income, net, decreased by $6.2 million to $9.7 million in 2025 from $15.9 million in 2024, primarily due to lower average cash and investment balances.

The increase in research and development expenses was primarily driven by a $27.1 million increase in contract manufacturing expenses supporting tanruprubart global regulatory submissions and the manufacturing technology transfer of vonaprument to a commercial-ready facility. Additionally, direct clinical and nonclinical outside services costs increased by $21.9 million due to the vonaprument Phase 3 ARCHER II trial in GA and the initiation of the tanruprubart FORWARD study in GBS. Compensation and personnel-related expenses within R&D increased by $10.0 million due to higher headcount, and consulting and professional services expenses increased by $6.0 million due to global regulatory submissions and the ARCHER II trial. The decrease in general and administrative expenses was mainly due to a $2.6 million decrease in consulting and professional services costs, reflecting corporate efficiencies and disciplined resource prioritization, and a $1.2 million decrease in compensation and personnel-related expenses due to the full amortization of previously granted high fair value stock options, partially offset by higher headcount.

During the reported period, significant operational developments included the completion of enrollment of 659 patients in the Phase 3 ARCHER II trial for vonaprument in July 2025. The company also filed an MAA with the EMA for tanruprubart for the treatment of GBS in January 2026. In June 2025, the company amended common warrants exercisable for 6,877,622 shares of common stock, extending their term by one year until June 30, 2026, and removing the cashless exercise option, which resulted in a deemed dividend of $1.9 million .

Business Outlook

Annexon expects its existing capital resources, consisting of cash and cash equivalents and short-term investments of $238.3 million as of December 31, 2025, to fund planned operating expenses into the second half of 2027 . The company anticipates requiring substantial additional financing to achieve its goals, and a failure to obtain this capital could force delays, limits, reductions, or termination of product development programs, commercialization efforts, or other operations. Management expects to continue incurring losses and negative cash flows from operations for at least the next several years.

A major growth area for the company is the advancement of tanruprubart towards its first potential approval in Guillain-Barré Syndrome (GBS). The company filed an MAA with the EMA for tanruprubart for GBS in January 2026 and plans to submit a Biologics License Application (BLA) to the FDA in 2026 . Initial pharmacokinetics (PK), pharmacodynamics (PD), biomarker, and functional data from the ongoing open-label FORWARD study in the U.S. and Europe are anticipated in 2026 to supplement the comprehensive data package for tanruprubart in GBS. This data will be used to engage with the FDA to reach alignment on the generalizability of tanruprubart in Western patients for BLA submission.

Another significant growth area is vonaprument for dry AMD with Geographic Atrophy (GA). The company completed enrollment of 659 patients in the global, sham-controlled, double-masked Phase 3 ARCHER II trial in July 2025 . Topline data from ARCHER II is planned for release in the fourth quarter of 2026 . The company has established a global registration path with the FDA and EMA, with the single-study program to be analyzed as two sub-studies in the U.S. in accordance with the FDA’s two-trial recommendation. Vonaprument has received Priority Medicine (PRIME) designation by the EMA and was selected for the Product Development Coordinator Pilot launched in July 2025 to facilitate regulatory interactions.

The company also plans to expand its targeted immunotherapy platform by leveraging learnings from its late-stage programs to inform clinical development in "next wave" neuroinflammatory diseases. This includes advancing ANX1502, a novel oral small molecule, with an update upon study completion in 2026 . The company intends to efficiently prosecute opportunities across its portfolio to create near-term value for patients, physicians, and stakeholders.

Operationally, the company expects its future research and development expenses to increase as it pursues regulatory approval of product candidates, advances them through late-stage clinical trials, invests in manufacturing capabilities for commercialization, and hires additional personnel. General and administrative expenses are also expected to increase to support R&D activities, business growth, and public company operations. The company plans to establish long-term supply agreements with manufacturers and to establish supply arrangements with alternative larger-scale suppliers to ensure continuity in its supply chain.

Regarding capital allocation, the company recently entered into a new sales agreement with TD Cowen on March 30, 2026 , allowing it to offer and sell up to $150.0 million of common stock through an at-the-market offering program. As of December 31, 2025, approximately $66.9 million remained available under the 2024 ATM program, and subsequent to that date, the company sold 6,049,762 shares for net proceeds of approximately $32.8 million . The company does not currently intend to pay any cash dividends on its common stock for the foreseeable future, preferring to invest future earnings, if any, to fund growth.

Risk Factors

Annexon faces several material risks, including its status as a clinical-stage biopharmaceutical company with a limited operating history and no approved products, having incurred significant losses of $206.7 million in 2025 and an accumulated deficit of $917.4 million as of December 31, 2025. The company will require substantial additional financing, and failure to obtain it could force delays or termination of product development. The business is heavily dependent on the successful development and regulatory approval of product candidates, some in early clinical stages, with no assurance of regulatory approval or commercialization. Research and development is inherently risky, and product candidates may not receive regulatory approval. Clinical trials may experience substantial delays or not be completed on expected timelines due to various factors, including patient enrollment difficulties, regulatory disagreements on trial design, or unforeseen safety issues. Adverse events or undesirable side effects from product candidates could halt development, delay or prevent approval, limit commercial potential, or result in negative consequences. The company relies on third-party suppliers for manufacturing, and their failure to comply with regulations or provide sufficient quantities could materially affect the business. Successful commercialization depends on adequate coverage, reimbursement levels, and pricing policies from governmental authorities and health insurers, which may be difficult to obtain or maintain. Any future collaboration arrangements may not be successful. The company's ability to obtain, maintain, and enforce intellectual property protection is critical, and failure to do so could adversely affect its competitive position. The stock price has been volatile and could remain so. Actual or perceived failure to comply with data protection laws, including the EU GDPR and UK GDPR, which can impose fines of up to €20 million or 4% of annual global revenue , could lead to enforcement actions, penalties, and negative impacts on operations. The company is also subject to U.S. and foreign export/import controls, sanctions, embargoes, anti-corruption, and anti-money laundering laws. Unfavorable global and macroeconomic conditions, including inflation and rising interest rates, and international trade policies, such as tariffs, could adversely affect the business. Natural disasters, particularly in the San Francisco Bay Area where headquarters are located, could disrupt operations. Misconduct by employees or third-party contractors, including noncompliance with regulatory standards, could lead to penalties. The use of hazardous materials in research and development requires compliance with environmental laws, which can be expensive. The company's ability to use its net operating loss carryforwards and other tax attributes may be limited by ownership changes under Sections 382 and 383 of the Internal Revenue Code, with $0.1 million of federal and $34.7 million of state NOLs identified to expire unused through December 31, 2025.

Management Priorities

Management's message emphasizes the company's focus on advancing its next-generation platform of targeted immunotherapies for complement-mediated neuroinflammatory diseases, impacting nearly 10 million people worldwide. They highlight over a decade of expertise in stopping neuroinflammation and demonstrated robust target engagement and clinical proof of concept across multiple diseases. The strategic priorities include advancing two late-stage registrational programs: tanruprubart for Guillain-Barré Syndrome (GBS) and vonaprument for geographic atrophy (GA), as well as developing ANX1502, a novel oral small molecule for autoimmune conditions. Management plans to submit a biologics license application (BLA) to the FDA for GBS in 2026 and anticipates reporting topline data for the Phase 3 ARCHER II trial in GA in the fourth quarter of 2026 . They also plan to provide an update on the ANX1502 study completion in 2026 . Management believes existing cash and cash equivalents and short-term investments of $238.3 million will fund operating expenses into the second half of 2027 , but acknowledges the need for substantial additional financing.

View Source Annual Report on SEC.gov ↗

References

  1. [1] Item 1, Business — Overview
  2. [2] Item 1, Business — Overview
  3. [3] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  4. [4] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  5. [5] Item 7, MD&A — Overview
  6. [6] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  7. [7] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  8. [8] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  9. [9] Item 7, MD&A — Results of Operations Comparison of the Years Ended December 31, 2025 and 2024
  10. [10] Item 7, MD&A — Research and Development Expenses
  11. [11] Item 7, MD&A — Research and Development Expenses
  12. [12] Item 7, MD&A — Research and Development Expenses
  13. [13] Item 7, MD&A — Research and Development Expenses
  14. [14] Item 7, MD&A — General and Administrative Expenses
  15. [15] Item 7, MD&A — General and Administrative Expenses
  16. [16] Item 7, MD&A — General and Administrative Expenses
  17. [17] Item 7, MD&A — General and Administrative Expenses
  18. [18] Item 7, MD&A — Interest and other income, net
  19. [19] Item 7, MD&A — Interest and other income, net
  20. [20] Item 7, MD&A — Interest and other income, net
  21. [21] Item 7, MD&A — Research and Development Expenses
  22. [22] Item 7, MD&A — Research and Development Expenses
  23. [23] Item 7, MD&A — Research and Development Expenses
  24. [24] Item 7, MD&A — Research and Development Expenses
  25. [25] Item 7, MD&A — General and Administrative Expenses
  26. [26] Item 7, MD&A — General and Administrative Expenses
  27. [27] Item 1, Business — Geographic Atrophy
  28. [28] Item 7, MD&A — 2022 Financing
  29. [29] Item 7, MD&A — 2022 Financing
  30. [30] Item 7, MD&A — Liquidity and Capital Resources
  31. [31] Item 7, MD&A — Funding Requirements
  32. [32] Item 7, MD&A — Overview
  33. [33] Item 7, MD&A — Overview
  34. [34] Item 7, MD&A — Overview
  35. [35] Item 7, MD&A — Overview
  36. [36] Item 7, MD&A — Overview
  37. [37] Item 7, MD&A — Overview
  38. [38] Item 7, MD&A — Overview
  39. [39] Item 7, MD&A — Ongoing Development of ANX1502 in Autoimmune Diseases
  40. [40] Item 7, MD&A — 2026 At the Market (ATM) Program
  41. [41] Item 7, MD&A — 2026 At the Market (ATM) Program
  42. [42] Item 7, MD&A — 2024 ATM Program
  43. [43] Item 7, MD&A — 2024 ATM Program
  44. [44] Item 7, MD&A — 2024 ATM Program
  45. [45] Item 7, MD&A — Overview
  46. [46] Item 7, MD&A — Overview
  47. [47] Item 1A, Risk Factors — Data Privacy and Security Laws
  48. [48] Item 1A, Risk Factors — Data Privacy and Security Laws
  49. [49] Item 1A, Risk Factors — Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.
  50. [50] Item 1A, Risk Factors — Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.
  51. [51] Item 7, MD&A — Overview
  52. [52] Item 7, MD&A — Overview
  53. [53] Item 7, MD&A — Ongoing Development of ANX1502 in Autoimmune Diseases
  54. [54] Item 7, MD&A — Liquidity and Capital Resources
  55. [55] Item 7, MD&A — Funding Requirements

Analysis on 5/19/2026