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Form 8-K

sec.gov

8-K — Annexon, Inc.

Accession: 0001193125-26-345672

Filed: 2026-08-12

Period: 2026-08-12

CIK: 0001528115

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Results of Operations and Financial Condition

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — d119960d8k.htm (Primary)

EX-99.1 (d119960dex991.htm)

EX-99.2 (d119960dex992.htm)

GRAPHIC (g119960dsp1.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K

8-K (Primary)

Filename: d119960d8k.htm · Sequence: 1

8-K

false 0001528115 0001528115 2026-08-12 2026-08-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 12, 2026

ANNEXON, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-39402

27-5414423

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

1400 Sierra Point Parkway, Bldg C, Suite 200

Brisbane, California 94005

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (650) 822-5500

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, par value $0.001 per share

ANNX

The Nasdaq Stock Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02

Results of Operations and Financial Condition.

On August 12, 2026, Annexon, Inc. (the “Company”) announced certain financial results for the second quarter ended June 30, 2026. A copy of the Company’s press release, titled “Annexon Reports Second Quarter 2026 Financial Results, Business Updates and Key Anticipated Milestones” is furnished pursuant to Item 2.02 as Exhibit 99.1 hereto.

The information in Item 2.02 of this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section or Section 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in Item 2.02 of this Current Report on Form 8-K, including Exhibit 99.1, shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing, except as expressly set forth by specific reference in such a filing.

Item 8.01.

Other Events.

On August 12, 2026, the Company issued a press release titled “Annexon Expands Vonaprument Phase 3 Program in Geographic Atrophy to Add Month 24 Dual Primary Endpoint Complementing Month 15 Primary Endpoint and Launch Open-Label Extension Study.” A copy of the press release is attached as Exhibit 99.2 to this Current Report on Form 8-K and, other than the quotes contained therein, is incorporated herein by reference.

Item 9.01.

Financial Statements and Exhibits.

(d) Exhibits.

Exhibit

No.

Description

99.1

Press release, dated August 12, 2026, titled “Annexon Reports Second Quarter 2026 Financial Results, Business Updates and Key Anticipated Milestones”.

99.2

Press release, dated August 12, 2026, titled “Annexon Expands Vonaprument Phase 3 Program in Geographic Atrophy to Add Month 24 Dual Primary Endpoint Complementing Month 15 Primary Endpoint and Launch Open-Label Extension Study”.

104.1

Cover Page Interactive Data File, formatted in inline XBRL.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: August 12, 2026

Annexon, Inc.

By:

/s/ Jennifer Lew

Jennifer Lew

Executive Vice President and Chief Financial Officer

EX-99.1

EX-99.1

Filename: d119960dex991.htm · Sequence: 2

EX-99.1

Exhibit 99.1

Annexon Reports Second Quarter 2026 Financial Results, Business Updates and Key Anticipated Milestones

Rapid, Positive Clinical Outcomes in GBS FORWARD Study Reinforce Consistency and Reproducibility of Tanruprubart Treatment Effect

Demonstrated in Phase 3 and Real-World Evidence Studies; BLA Submission Expected in Q4 2026

Vonaprument Phase 3 GA Program Expanded

with Month 15 / 24 Dual Primary Endpoint Strategy and Launch of Open-Label Extension Study; Month 15 Primary Endpoint on Track for Q4 2026

POC Data for ANX1502, a First-in-Kind Oral C1 Inhibitor for

Autoimmune Disease, Expected in Fall 2026

$200 Million Credit Facility Strengthens Balance Sheet and Capabilities; Anticipated

Runway Extended into 2028

Company to Host Business Update Call Today at 8:00 a.m. ET

BRISBANE, Calif., August 12, 2026 – Annexon, Inc. (Nasdaq: ANNX), a biopharmaceutical company advancing the next

generation platform of targeted immunotherapies aimed at neuroinflammatory diseases that impact nearly 10 million people worldwide, today highlighted portfolio progress, announced key anticipated milestones, and reported second quarter 2026

financial results. The Company will host a business update call today at 8:00 a.m. ET to discuss corporate and clinical developments across its C1q-focused neuroinflammatory pipeline. Please register for the

event here.

“2026 is a defining year for our company, with meaningful progress across both our Guillain-Barré syndrome (GBS) and

geographic atrophy (GA) programs that position us to potentially deliver two transformative therapies for millions of patients in need. The quality and consistency of the data generated to date reinforce our confidence in the differentiated

potential of our C1q-targeted approaches to address neuroinflammatory diseases at their source, and we are encouraged by the growing enthusiasm from patients and physicians,” said Douglas Love, president

and chief executive officer of Annexon. “With our leadership capabilities and financial position strengthened, we are entering an exciting period of execution, with multiple important clinical and regulatory milestones expected over the next 6

to 12 months and a significant opportunity to create value for patients and stakeholders.”

2026 Strategic Priorities and Key Milestones

Tanruprubart: Potential to be the first targeted, fast-acting therapy for GBS, an indiscriminate life-threatening neuromuscular emergency affecting 150,000

people annually worldwide and driving an estimated $20+ billion annual healthcare burden in the U.S.

Early improvement in strength and clinically meaningful reduction in disability shown with tanruprubart in the

first ten U.S. and European patients with GBS from the ongoing, open-label FORWARD study. Early outcomes reinforce the consistency and reproducibility of tanruprubart treatment effect previously demonstrated in Phase 3 and real-world evidence

studies.

EU Marketing Authorisation Application under review with the European Medicines Agency supported by robust data

package demonstrating rapid benefit on function and disability in placebo-controlled studies and Real-World Evidence study demonstrating favorable outcomes versus current treatments, intravenous immunoglobulin and plasma exchange.

Next Milestone: Biologics License Application (BLA) submission with U.S./European data from FORWARD trial

expected in fourth quarter of 2026.

Vonaprument: Potential to be the first targeted vision-preserving therapy for GA, a leading

cause of blindness affecting more than 8 million patients worldwide.

The ongoing, global, double masked Phase 3 ARCHER II trial remains on track, and all eligible patients have

received at least 12 months of treatment, with masked event accrual consistent with projected timelines. Vonaprument continues to be generally well-tolerated with a low discontinuation rate (<10%) and high compliance (>95%), reinforcing

significant enthusiasm by physicians/patients.

To maximize the

best-in-class potential of vonaprument, a Month 24 dual primary endpoint was added while maintaining the Month 15 primary endpoint.

This strategic enhancement was enabled by the strong power and execution of the Phase 3 ARCHER II trial. With a dual primary endpoint strategy, ARCHER II can achieve success in protecting against vision loss at either Month 15 or 24, which are

independent efficacy timepoints.

Annexon also launched an open-label extension (OLE) study to evaluate the the long-term safety and benefit of

vonaprument in patients with GA. Following completion of the 2-year ARCHER II study, all patients have the option to receive monthly vonaprument treatment in the OLE study.

Next Milestones: Month 15 primary endpoint on track for the fourth quarter of 2026, with final trial

completion, including the Month 24 primary endpoint expected in the third quarter of 2027.

ANX1502 for Autoimmune

Conditions: First-in-kind oral small molecule inhibiting activated C1s, with convenient and flexible dosing.

Dosing is complete. The ongoing

proof-of-concept (POC) study is evaluating pharmacokinetics (PK) and pharmacodynamics (PD) in relation to food intake, and reduction in complement and bilirubin markers

as a measure of hemolysis in patients with cold agglutinin disease (CAD).

Next Milestone: Update on POC trial in CAD anticipated in the Fall of 2026.

Corporate Updates

Entered into a strategic credit facility of up to $200 million with Oxford Finance LLC, with an initial

$50 million drawn at closing, bolstering Annexon’s financial position, and diversifying its capital structure.

Appointed Mark S. Blumenkranz, M.D., M.M.S., a retinal surgeon and biotechnology entrepreneur with more than four

decades of clinical, scientific and corporate leadership experience, to Annexon’s board of directors as the Company prepares for potential commercialization.

Second Quarter 2026 Financial Results

Cash and operating runway: Cash, cash equivalents and short-term investments were $209.2 million as

of June 30, 2026. Annexon’s current cash, cash equivalents and short-term investments and funds from the credit facility are expected to fund operations and anticipated milestones into 2028.

Research and development (R&D) expenses: R&D expenses were $46.6 million for the quarter

ended June 30, 2026, compared to $44.2 million for the quarter ended June 30, 2025. The change in R&D expenses is primarily associated with the Phase 3 ARCHER II trial of vonaprument in GA and contract manufacturing expenses of

our product candidates.

General and administrative (G&A) expenses: G&A expenses were $10.6 million for the quarter

ended June 30, 2026, compared to $7.6 million for the quarter ended June 30, 2025. The change in G&A expenses reflects ongoing corporate consulting and professional services costs for the advancement of our registrational

programs.

Net loss: Net loss attributable to common stockholders was $55.3 million or $0.28 per share for the

quarter ended June 30, 2026, compared to $49.2 million or $0.34 per share for the quarter ended June 30, 2025.

Corporate Webcast Details

Annexon will host a webcast at

8:00 a.m. ET today, August 12, 2026. Please register for the webcast here. The live webcast and replay may be also accessed by visiting Annexon’s website at

https://ir.annexonbio.com/events-and-presentations/events.

About Annexon

Annexon Biosciences (Nasdaq: ANNX) is

advancing the next generation platform of targeted immunotherapies for nearly 10 million people worldwide living with serious neuroinflammatory diseases. Our founding scientific approach focuses on C1q, the initiating molecule of a potent

inflammatory pathway that when misdirected can lead to tissue damage and loss of function in a host of diseases. Our targeted therapies are designed to stop classical complement-driven neuroinflammation at its source to provide meaningful functional

benefit and alter the course of disease. Annexon’s mission is to deliver game-changing therapies to patients so that they can live their best lives. To learn more visit annexonbio.com.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E

of the Securities Exchange Act of 1934, as amended. In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,”

“contemplate,” “continue,” “could,” “design,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,”

“plan,” “positioned,” “potential,” “predict,” “seek,” “should,” “target,” “will,” “would” and other similar expressions that are predictions

of or indicate future events and future trends, or the negative of these terms or other comparable terminology. All statements other than statements of historical facts contained in this press release are forward-looking statements. These

forward-looking statements include, but are not limited to, statements about: the potential for the company’s two late stage registrational programs to improve the lives of millions of patients; timing of and topline data from the Month 15

primary endpoint and Month 24 primary endpoint in the pivotal Phase 3 ARCHER II trial; the potential of vonaprument to be the first targeted vision-preserving therapy for GA; the potential of tanruprubart to be the first targeted and fast-acting

therapy for GBS; expectation of multiple important clinical and regulatory milestones over the next 6 to 12 months; timing of a BLA submission with supportive initial U.S./European data from FORWARD trial; timing of POC trial data for ANX1502 in

CAD; anticipated cash runway into 2028; and continuing advancement of the company’s portfolio. Forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties that could cause actual results and

events to differ materially from those anticipated, including, but not limited to, risks and uncertainties related to: the final results from the Phase 3 ARCHER II trial; the company’s history of net operating losses; the company’s

ability to obtain necessary capital to fund its clinical programs; the potential for delays in the company’s clinical trials, including if the FDA and comparable foreign regulatory authorities do not accept data from clinical trials for

product candidates outside the United States; the early stages of clinical development of the company’s product candidates; the effects of public health crises on the company’s clinical programs and business operations; the

company’s ability to obtain regulatory approval of and successfully commercialize its product candidates; any undesirable side effects or other properties of the company’s product candidates; the company’s reliance on third-party

suppliers and manufacturers; the outcomes of any future collaboration agreements; and the company’s ability to adequately maintain intellectual property rights for its product candidates. These and other risks are described in greater detail

under the section titled “Risk Factors” contained in the company’s most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q and the

company’s other filings with the Securities and Exchange Commission. Any forward-looking statements that the company makes in this press release are made pursuant to the Private Securities Litigation Reform Act of 1995, as amended, and speak

only as of the date of this press release. Except as required by law, the company undertakes no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise.

Investor Contact:

Joyce Allaire

LifeSci Advisors

jallaire@lifesciadvisors.com

Media Contact:

Beth Keshishian

917-912-7195

beth@bethkeshishian.com

ANNEXON, INC.

Condensed Consolidated Statements of Operations (Unaudited)

(in thousands, except share and per share amounts)

Three Months Ended

June 30,

Six Months Ended

June 30,

2026

2025

2026

2025

Operating expenses:

Research and development (1)

$

46,590

$

44,160

$

82,376

$

92,339

General and administrative (1)

10,637

7,566

20,904

16,792

Total operating expenses

57,227

51,726

103,280

109,131

Loss from operations

(57,227

)

(51,726

)

(103,280

)

(109,131

)

Interest and other income, net

1,879

2,570

3,790

5,619

Net loss

(55,348

)

(49,156

)

(99,490

)

(103,512

)

Deemed dividend on modification of common stock warrants

(1,857

)

(1,857

)

Net loss attributable to common stockholders

$

(55,348

)

$

(51,013

)

$

(99,490

)

$

(105,369

)

Net loss per share, basic and diluted

$

(0.28

)

$

(0.34

)

$

(0.50

)

$

(0.71

)

Weighted-average shares used in computing net loss per share, basic and diluted

201,003,269

148,320,803

197,620,477

148,215,392

(1)

Includes the following stock-based compensation expense:

Research and development

$  2,663

$  2,688

$  5,031

$  5,517

General and administrative

$  2,150

$  1,517

$  3,938

$  3,766

ANNEXON, INC.

Condensed Consolidated Balance Sheets (Unaudited)

(in thousands)

June 30,

2026

December 31,

2025

(Unaudited)

Assets

Current assets:

Cash and cash equivalents

$

199,270

$

162,051

Short-term investments

9,973

76,294

Prepaid expenses and other current assets

3,514

3,846

Total current assets

212,757

242,191

Restricted cash

1,032

1,032

Property and equipment, net

9,675

10,617

Operating lease

right-of-use assets

14,333

15,185

Other non-current assets

8,271

8,546

Total assets

$

246,068

$

277,571

Liabilities and Stockholders’ Equity

Current liabilities:

Accounts payable

$

15,731

$

14,931

Accrued and other current liabilities

19,625

24,791

Operating lease liabilities, current

3,126

2,908

Total current liabilities

38,482

42,630

Operating lease liabilities, non-current

21,525

23,293

Total liabilities

60,007

65,923

Stockholders’ equity:

Common stock

175

149

Additional paid-in capital

1,202,847

1,128,917

Accumulated other comprehensive loss

(82

)

(29

)

Accumulated deficit

(1,016,879

)

(917,389

)

Total stockholders’ equity

186,061

211,648

Total liabilities and stockholders’ equity

$

246,068

$

277,571

EX-99.2

EX-99.2

Filename: d119960dex992.htm · Sequence: 3

EX-99.2

Exhibit 99.2

Annexon Expands Vonaprument Phase 3 Program in Geographic Atrophy with Addition of Month 24 Dual Primary

Endpoint Complementing Month 15 Primary Endpoint and Launch of Open-Label Extension Study

Strong Execution of Well-Powered ARCHER

II Trial Reaffirms Month 15 Primary Endpoint on Track for Q4 2026

Strategic Expansion Underscores Vonaprument’s Best-in-Class Potential as the First and Only Treatment for Vision Preservation in GA

BRISBANE, Calif., August 12, 2026 – Annexon, Inc. (Nasdaq: ANNX), a biopharmaceutical company advancing the next generation

platform of targeted immunotherapies for multiple neuroinflammatory diseases that impact nearly 10 million people worldwide, today announced the addition of a Month 24 dual primary endpoint to complement the current Month 15 primary endpoint in

its Phase 3 ARCHER II trial, and launch of an open-label extension (OLE) study of vonaprument for the treatment of dry age-related macular degeneration (AMD) with geographic atrophy (GA). With a dual primary

endpoint strategy, ARCHER II can achieve success in protecting against vision loss at either Month 15 or 24, which are independent efficacy timepoints.

“Our objective is to maximize the best-in-class potential of vonaprument

to preserve visual acuity for millions of patients at risk of irreversible vision loss. The strong power and execution of our Phase 3 ARCHER II trial provide a clear opportunity to seamlessly incorporate a Month 24 dual primary endpoint while

maintaining the Month 15 primary endpoint,” said Douglas Love, president and chief executive officer of Annexon. “As ARCHER II was already designed to remain masked through Month 24, this strategic addition allows us to also evaluate the

longer-term profile of vonaprument for inclusion into the label without change to the study operation. We look forward to delivering the Month 15 data milestone on schedule in the fourth quarter of this year and delivering Month 24 data thereafter

as a separate and additional assessment.”

In the ongoing global, double-masked Phase 3 ARCHER II trial, all eligible patients have received at

least 12 months of treatment, with masked event accrual in line with projections. The study retains strong statistical power and continues to be well-executed with a low discontinuation rate (<10%) and high compliance (>95%), reinforcing

significant enthusiasm by physicians and patients. Upon completion of Month 24, all patients have the option to receive monthly vonaprument treatment in the OLE study. The OLE study is designed to evaluate the long-term safety and benefit of

vonaprument in patients with GA.

An independent Data Monitoring Committee (DMC) will assess the primary endpoint of the overall study at Month 15, and

the Company expects to report the DMC’s assessment in the fourth quarter of 2026. Following this assessment, the DMC may recommend that the ARCHER II overall study has met its Month 15 primary endpoint, enabling the planned analysis of the

trial’s two sub-studies, with results anticipated in the first quarter of 2027; or it may recommend that the study continues until the Month 24 primary endpoint analysis. Completion of ARCHER II,

including the Month 24 analyses, is expected in the third quarter of 2027.

Vonaprument has received FastTrack Designation from the U.S. Food and Drug

Administration and is the only GA program to receive PRIME designation from the European Medicines Agency (EMA). Vonaprument was also selected by EMA for the exclusive Product Development Coordinator (PDC) pilot launched in July 2025 to assist PRIME

designation holders in navigating regulatory interactions, including expedited scientific advice, Marketing Authorisation Application submission readiness activities, and ad-hoc queries throughout the

development program.

About Vonaprument (formerly ANX007)

Vonaprument is a clinical-stage investigational antigen-binding fragment (Fab) designed as a

first-in-kind therapeutic to selectively inhibit C1q, the initiating molecule of the classical complement pathway and a key driver of neurodegeneration. It is formulated

for intravitreal (IVT) administration, with the potential to be the first targeted vision-preserving therapy for GA. Vonaprument involves a differentiated neuroprotective approach designed to protect photoreceptor cells and retinal function by

blocking C1q and the entire classical pathway, while allowing for normal immune activity of the lectin and alternative complement pathways. Vonaprument has been granted Fast Track designation from the U.S. Food and Drug Administration (FDA) and is

the first therapeutic candidate for the treatment of GA to receive Priority Medicine (PRIME) designation from the EMA for the treatment of GA.

About

the Phase 2 ARCHER Trial

ARCHER is a successfully completed, randomized, multi-center, double-masked, sham-controlled Phase 2 trial that evaluated

vonaprument in a broad population of patients with GA. Across multiple measures, vonaprument consistently preserved visual function and ellipsoid zone retinal structure, reinforcing the therapeutic potential of protecting photoreceptor health early

in disease progression. Vonaprument provided significant, time and dose-dependent protection from vision loss as measured by confirmed best corrected visual acuity (BCVA) ≥15-letter loss, the widely

accepted and clinically meaningful functional endpoint. Significant protection from vision loss was also shown in other prespecified measures of BCVA and visual function, including low luminance visual acuity (LLVA) and low luminance visual deficit

(LLVD). Vonaprument was also shown to protect key retinal structures important for vision, including significant protection of photoreceptors as measured by optical coherence tomography (OCT). Vonaprument was generally well-tolerated through month

12, with no increase in choroidal neovascularization (CNV) rates between the treated and sham arms and no events of retinal vasculitis reported.

About the Phase 3 ARCHER II Trial

ARCHER II is an ongoing global, pivotal, Phase 3 sham-controlled, double-masked trial of vonaprument in 659 patients with GA, a disease driven by early

photoreceptor degeneration leading to vision loss. Enrollment was completed in July 2025. The primary endpoints of this two-year trial are the proportion of patients with confirmed best corrected visual acuity

15-letter loss at two consecutive visits, measured through months 15 and 24. Best corrected visual acuity (BCVA) ≥15-letter loss represents three lines on the

standard Early Treatment of Diabetic Retinopathy Study (ETDRS) eye chart. Proportion of patients experiencing BCVA ≥15-letter loss is a well-established functional endpoint that has served as the basis

for numerous ophthalmology drug approvals by the FDA and European Medicines Agency. Secondary endpoints in ARCHER II include safety, LLVA, and photoreceptor integrity (EZ). A global registration path has been established with U.S. and European

regulators for ARCHER II. ARCHER II is a single protocol that will also be analyzed as two sub-studies after meeting the primary endpoint. Topline results from the Month 15 primary analysis are expected in the

fourth quarter of 2026.

About Annexon

Annexon

Biosciences (Nasdaq: ANNX) is advancing the next generation platform of targeted immunotherapies for nearly 10 million people worldwide living with serious neuroinflammatory diseases. Our founding scientific approach focuses on C1q, the

initiating molecule of a potent inflammatory pathway that when misdirected can lead to tissue damage and loss of function in a host of diseases. Our targeted therapies are designed to stop classical complement-driven neuroinflammation at its source

to provide meaningful functional benefit and alter the course of disease. Annexon’s mission is to deliver game-changing therapies to patients so that they can live their best lives. To learn more visit annexonbio.com.

Forward Looking Statements

This press release contains

forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. In some cases, you can identify forward-looking statements by

terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “design,” “due,” “estimate,”

“expect,” “goal,” “intend,” “may,” “objective,” “plan,” “positioned,” “potential,” “predict,” “seek,” “should,”

“target,” “will,” “would” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. All statements other

than statements of historical facts contained in this press release are forward-looking statements. These forward-looking statements include, but are not limited to the potential for vonaprument to be the first targeted vision-preserving therapy for

GA; timing of and results from the Phase 3 ARCHER II trial, including expected month 15 primary endpoint in the fourth quarter of 2026 and the month 24 dual primary endpoint analyses expected in the third quarter of 2027; planned analysis of the

ARCHER II trial’s two sub-studies, with results anticipated in the first quarter of 2027; opportunity for patients to receive monthly vonaprument treatment in the OLE study; the company’s ability

to commercialize its product candidates, if approved; and continuing advancement of the company’s portfolio. Forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties that could cause actual

results and events to differ materially from those anticipated, including, but not limited to, risks and uncertainties related to: the company’s history of net operating losses; the company’s ability to obtain necessary capital to fund

its clinical programs; the potential for delays in the company’s clinical trials; the potential for the company’s product candidates to not receive regulatory approval, including if the FDA and comparable foreign regulatory authorities

determine that the company’s submission package is not sufficient or require the company to provide additional data in patients that are not feasible to obtain; the early stages of clinical development of the company’s product

candidates; the effects of public health crises on the company’s clinical programs and business operations; the company’s ability to obtain regulatory approval of and successfully commercialize its product candidates; any undesirable

side effects or other properties of the company’s product candidates; the company’s reliance on third-party suppliers and manufacturers; the outcomes of any future collaboration agreements; and the company’s ability to adequately

maintain intellectual property rights for its product candidates. These and other risks are described in greater detail under the section titled “Risk Factors” contained in the company’s Annual Report on Form 10-K and Quarterly Reports on Form 10-Q and the company’s other filings with the Securities and Exchange Commission. Any forward-looking statements that the company

makes in this press release are made pursuant to the Private Securities Litigation Reform Act of 1995, as amended, and speak only as of the date of this press release. Except as required by law, the company undertakes no obligation to publicly

update any forward-looking statements, whether as a result of new information, future events or otherwise.

Investor Contact:

Joyce Allaire

LifeSci Advisors

jallaire@lifesciadvisors.com

Media Contact:

Beth Keshishian

917-912-7195

beth@bethkeshishian.com

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Document Type

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Document Period End Date

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Entity Registrant Name

ANNEXON, INC.

Entity Incorporation State Country Code

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Entity File Number

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Entity Tax Identification Number

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Entity Address, Address Line One

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Entity Address, Address Line Two

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false

Pre Commencement Tender Offer

false

Pre Commencement Issuer Tender Offer

false

Security 12b Title

Common Stock, par value $0.001 per share

Trading Symbol

ANNX

Security Exchange Name

NASDAQ

Entity Emerging Growth Company

false

X

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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No definition available.

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- Definition

Area code of city

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No definition available.

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Namespace Prefix:

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- Definition

Cover page.

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No definition available.

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- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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No definition available.

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Data Type:

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Balance Type:

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Period Type:

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- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

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Data Type:

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Period Type:

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- Definition

Address Line 1 such as Attn, Building Name, Street Name

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No definition available.

+ Details

Name:

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Namespace Prefix:

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Data Type:

xbrli:normalizedStringItemType

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Period Type:

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- Definition

Address Line 2 such as Street or Suite number

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No definition available.

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Name:

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Namespace Prefix:

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Data Type:

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Balance Type:

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Period Type:

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- Definition

Address Line 3 such as an Office Park

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Name:

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Data Type:

xbrli:normalizedStringItemType

Balance Type:

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Period Type:

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- Definition

Name of the City or Town

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No definition available.

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Name:

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Namespace Prefix:

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Data Type:

xbrli:normalizedStringItemType

Balance Type:

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Period Type:

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- Definition

Code for the postal or zip code

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No definition available.

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Namespace Prefix:

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Data Type:

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Balance Type:

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Period Type:

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- Definition

Name of the state or province.

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No definition available.

+ Details

Name:

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Namespace Prefix:

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Data Type:

dei:stateOrProvinceItemType

Balance Type:

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Period Type:

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- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

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Namespace Prefix:

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- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

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-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

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Namespace Prefix:

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- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

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Data Type:

dei:fileNumberItemType

Balance Type:

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Period Type:

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- Definition

Two-character EDGAR code representing the state or country of incorporation.

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No definition available.

+ Details

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Namespace Prefix:

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Data Type:

dei:edgarStateCountryItemType

Balance Type:

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Period Type:

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- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

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Name:

dei_EntityRegistrantName

Namespace Prefix:

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Data Type:

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Balance Type:

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Period Type:

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- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

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Data Type:

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Period Type:

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- Definition

Local phone number for entity.

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No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

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Data Type:

xbrli:normalizedStringItemType

Balance Type:

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Period Type:

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- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

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Namespace Prefix:

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Data Type:

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Period Type:

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- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

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Namespace Prefix:

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- Definition

Title of a 12(b) registered security.

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-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

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- Definition

Name of the Exchange on which a security is registered.

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-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

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Namespace Prefix:

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Data Type:

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Period Type:

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- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

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Data Type:

xbrli:booleanItemType

Balance Type:

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Period Type:

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X

- Definition

Trading symbol of an instrument as listed on an exchange.

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No definition available.

+ Details

Name:

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Namespace Prefix:

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Data Type:

dei:tradingSymbolItemType

Balance Type:

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Period Type:

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X

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

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