# EDGAR Filing Document

**Accession Number:** 0001974640
**File Stem:** 0001193125-25-273250
**Filing Date:** 2025-11
**Character Count:** 31501
**Document Hash:** 183002faa62a410062f3bb5b809acea7
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-273250.hdr.sgml**: 20251110

**ACCESSION NUMBER**: 0001193125-25-273250

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 14

**CONFORMED PERIOD OF REPORT**: 20251110

**ITEM INFORMATION**: Results of Operations and Financial Condition

**ITEM INFORMATION**: Regulation FD Disclosure

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20251110

**DATE AS OF CHANGE**: 20251110

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Apogee Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001974640
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 934958665
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-41740
- **FILM NUMBER:** 251464332

**BUSINESS ADDRESS:**
- **STREET 1:** 221 CRESCENT ST.
- **STREET 2:** BUILDING 17, SUITE 102B
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453
- **BUSINESS PHONE:** 650-394-5230

**MAIL ADDRESS:**
- **STREET 1:** 221 CRESCENT ST.
- **STREET 2:** BUILDING 17, SUITE 102B
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Apogee Therapeutics, LLC
- **DATE OF NAME CHANGE:** 20230420

?xml version='1.0' encoding='ASCII'? 8-K

**UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549**

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## FORM 8-K

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**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

**Date of Report (Date of earliest event reported):** November 10, 2025<br>

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Apogee Therapeutics, Inc.

**(Exact name of Registrant as Specified in Its Charter)**

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| | | |
|:---|:---|:---|
| Delaware | 001-41740 | 93-4958665 |
| **(State or Other Jurisdiction<br>of Incorporation)** | **(Commission File Number)** | **(IRS Employer<br>Identification No.)** |
| 221 Crescent St., Bldg 17, Suite 102b |  |  |
| Waltham**,** Massachusetts |  | 02453 |
| **(Address of Principal Executive Offices)** |  | **(Zip Code)** |

---

**Registrant's Telephone Number, Including Area Code:** (650) 394-5230<br>

**(Former Name or Former Address, if Changed Since Last Report)**

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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:**

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| | | |
|:---|:---|:---|
| **<br>Title of each class** | **Trading<br>Symbol(s)** | **<br>Name of each exchange on which registered** |
| Common Stock, par value $0.00001 per share | APGE | The Nasdaq Global 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. ☐

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## Item 2.02 Results of Operations and Financial Condition.
On November 10, 2025, Apogee Therapeutics, Inc. (the "Company") issued a press release announcing its financial results for the quarter ended September 30, 2025 (the "Earnings Press Release").

A copy of the Earnings Press Release is furnished as Exhibit 99.1 to this Current Report on Form 8-K (the "Form 8-K") and is incorporated by reference herein. The exhibit furnished under Item 2.02 of this Form 8-K shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended (the "Securities Act"), regardless of any general incorporation language in such filing.

## Item 7.01 Regulation FD Disclosure.
On November 10, 2025, the Company issued a press release announcing positive interim Phase 1 results from the healthy volunteer trial of APG333 (the "Data Press Release").

A copy of the Data Press Release is furnished as Exhibit 99.2 to this Form 8-K and is incorporated by reference herein. The exhibit furnished under Item 7.01 of this Form 8-K shall not be deemed to be "filed" for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Exchange Act or the Securities Act, regardless of any general incorporation language in such filing.

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| | |
|:---|:---|
| **Item 9.01** | **Financial Statements and Exhibits.** |

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(d) *Exhibits*. The following exhibits are being furnished herewith:

**<u>EXHIBIT INDEX</u>**

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| | |
|:---|:---|
| **Exhibit<br>No.** | **Description** |
| 99.1 | [<u>Earnings Press Release, dated November 10, 2025</u>](apge-ex99_1.htm) |
| 99.2 | [<u>Data Press Release, dated November 10, 2025</u>](apge-ex99_2.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document). |

---

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**SIGNATURES**

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

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| | | | |
|:---|:---|:---|:---|
|  |  |  | Apogee Therapeutics, Inc. |
| Date: | November 10, 2025 | By:  | /s/ Michael Henderson, M.D. |
|  |  |  | Michael Henderson, M.D.<br>Chief Executive Officer |

---

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## Exhibit 99.1

![img126220792_0.jpg](img126220792_0.jpg)

**Apogee Therapeutics Provides Pipeline Progress and Reports Third Quarter 2025 Financial Results** 

*Pipeline programs continue to advance, with four clinical data readouts anticipated in 2026; APG777 trial readout timelines accelerated, with Phase 1b in asthma and APEX 52-week Part A data in AD anticipated in Q1 2026, APEX 16-week Part B data in AD in Q2 2026, and APG279 Phase 1b head-to-head readout against DUPIXENT in AD in 2H 2026*

*Interim Phase 1 results of APG333 in healthy volunteers reported today exceeded trial objectives, demonstrated a half-life of approximately 55 days, and suppressed key biomarkers for 6 months following a single dose, supporting potential 3- and 6- month dosing and the development of a quarterly or less frequently dosed co-formulation of APG273 (APG777+APG333) for respiratory indications*

*Completed $345 million public offering; $913 million cash, cash equivalents and marketable securities pro forma as of September 30*<sup>th</sup> *supports runway into 2H 2028* 

**San Francisco and Boston, November 10, 2025** – Apogee Therapeutics, Inc., (Nasdaq: APGE), a clinical-stage biotechnology company advancing optimized, novel biologics with potential for best-in-class profiles in the largest inflammatory and immunology (I&I) markets, today provided pipeline progress and reported third quarter 2025 financial results.

"Apogee is gearing up for a potentially transformative 2026 from a position of strength. With four key readouts coming in 2026 and the recent financing providing us runway through Phase 3 topline data for our lead program, APG777 in atopic dermatitis, we believe we are well positioned to advance our therapies to patients as quickly as possible," said Michael Henderson, M.D., Chief Executive Officer of Apogee. "In conjunction with our third quarter results, we are pleased to share first-in-human data for APG333, which, together with APG777, we believe could prove to be a best-in-class combination approach for respiratory indications, with the potential for dosing every three months or even less frequently. As we move into 2026, we look forward to advancing APG777's pipeline-in-a-product potential, beginning with the Phase 1b proof-of-concept readout in patients with asthma, followed by the Phase 2 Part A maintenance data in AD in the first quarter; Phase 2 Part B data in AD in the second quarter; and results from the APG279 Phase 1b head-to-head readout against DUPIXENT in AD in the second half of the year."

***Corporate & Pipeline Highlights and Upcoming Milestones***

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**APG777 continues to advance and has accelerated readout guidance with Phase 1b data in asthma, AD data from APEX 52-week Part A anticipated in Q1 2026, and APEX 16-week Part B data in Q2 2026:** APG777 is a novel, subcutaneous (SQ), extended half-life monoclonal antibody (mAb) targeting IL-13 – a critical cytokine in inflammation and a primary driver of AD.

oAt this year's European Academy of Dermatology and Venereology (EADV) 2025 Congress, the company shared updated data in a late-breaking oral presentation, highlighting that participants treated with APG777 observed statistically significant improvement in itch within 48 hours, as measured by mean percent change in I-NRS from baseline, and remained significant through Week 16. In July, APEX Part A met its primary endpoint, with APG777 demonstrating an EASI reduction from baseline of 71.0% compared to placebo at 33.8% (p < 0.001). APG777 was well tolerated with a safety profile consistent with other agents in the class.

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![img126220792_0.jpg](img126220792_0.jpg)

oThe Phase 1b trial of APG777 in patients with mild-to-moderate asthma is ongoing, with a readout expected in the first quarter of 2026. The trial is evaluating safety and tolerability, PK, and FeNO suppression by APG777.

o52-week data from the maintenance phase of APEX Part A are expected in the first quarter of 2026. The company aims to demonstrate the maintenance of EASI-75 and/or IGA 0,1 responses at levels similar or better than DUPIXENT but with quarterly or better dosing.

oPart B of the APEX trial is designed to find the optimized dose of APG777, looking at low, medium (Part A dose), and high dose regimens vs placebo. The trial has enrolled rapidly and has now expanded enrollment to 320 patients. The study is expected to finish enrolling by the end of 2026, enabling 16-week Part B data in the second quarter of 2026.

oPending results from Part A and Part B, the company plans to begin Phase 3 trials of APG777 in the second half of 2026.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**Phase 1b head-to-head study of APG279 (APG777+APG990) against DUPIXENT in AD continues to advance**: APG279 is the company's first combination treatment, combining APG990 and APG777. APG990 is a novel, SQ, extended half-life mAb targeting OX40L, and the combination with APG777 offers the potential for improved clinical responses over monotherapy across a variety of I&I diseases. Apogee's first-in-class approach of co-formulating these two extended half-life mAbs offers the potential for best-in-class efficacy and dosing.

oInterim readout from the head-to-head trial evaluating the safety, PK, pharmacodynamics and efficacy of APG279 vs. DUPIXENT in AD is expected in the second half of 2026.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**Completed $345 million public offering:** In October, Apogee completed an underwritten public equity offering, with aggregate gross proceeds of approximately $345.0 million (before deducting underwriting discounts, commissions, and other offering expenses) which supports cash runway into the second half 2028 and through APG777 Phase 3 topline data.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**Interim data from APG333 Phase 1 healthy volunteer trial support planned combination approach of APG273 (APG777+APG333):** APG333 is a novel, SQ, extended half-life mAb targeting thymic stromal lymphopoietin (TSLP), a clinically validated target that plays an important role in promoting immune cell recruitment and activation.

oToday, the company reported positive interim results from the Phase 1 clinical trial evaluating the safety, tolerability and PK of APG333 in 32 healthy adults across four cohorts. APG333 demonstrated data supporting potential 3- and 6-month dosing based on a half-life of approximately 55 days across doses tested. Additionally, APG333 was well tolerated across all cohorts, with doses of up to 1,000 mg. Key biomarkers of eosinophils and IL-5 showed depth of suppression in line with TSLP analogs and durability out to 6 months.

oResults support development of a quarterly or less frequently dosed co-formulation of APG273 (APG777+APG333) for respiratory indications.

**<u>Third Quarter 2025 Financial Results</u>**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**Cash Position**: Cash, cash equivalents and marketable securities were $588.9 million as of September 30, 2025, compared to $621.2 million as of June 30, 2025. In October, Apogee completed a $345 million underwritten public equity offering resulting in $913 million cash, cash equivalents and marketable securities on a pro forma basis as of September 30, 2025. Based on current operating plans, Apogee expects its existing total cash will enable the company to fund its operating expenses into the second half of 2028.

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![img126220792_0.jpg](img126220792_0.jpg)

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**R&D Expenses**: Research and development (R&D) expenses were $54.2 million for the quarter ended September 30, 2025, compared to $45.7 million for the quarter ended September 30, 2024. R&D expenses increased primarily due to the advancement of the pipeline and continued development of the company's programs, increases in personnel-related expenses and equity-based compensation associated with the growth in the company's R&D team.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**G&A Expenses**: General and administrative (G&A) expenses were $17.1 million for the quarter ended September 30, 2025, compared to $13.0 million for the quarter ended September 30, 2024. G&A expenses increased primarily due to increases in personnel-related expenses and equity-based compensation, primarily driven by increased headcount and an increase in the fair value of equity awards granted. These increases are the result of the company's expansion of operations to support the growth in its business.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•**Net Loss**: Net loss was $65.0 million for the quarter ended September 30, 2025, compared to a net loss of $49.0 million for the quarter ended September 30, 2024. Net loss increased primarily as a result of higher R&D and G&A expenses as described above.

**About Apogee**

Apogee Therapeutics is a clinical-stage biotechnology company advancing optimized, novel biologics with potential for best-in-class profiles in the largest I&I markets, including for the treatment of AD, asthma, EoE, COPD and other I&I indications. Apogee's antibody programs are designed to overcome limitations of existing therapies by targeting well-established mechanisms of action and incorporating advanced antibody engineering to optimize half-life and other properties. APG777, the company's most advanced program, is being initially developed for the treatment of AD, which is the largest and one of the least penetrated I&I markets. With four validated targets in its portfolio, Apogee is seeking to achieve best-in-class efficacy and dosing through monotherapies and combinations of its novel antibodies. Based on a broad pipeline and depth of expertise, the company believes it can deliver value and meaningful benefit to patients underserved by today's standard of care. For more information, please visit https://apogeetherapeutics.com.

**Forward Looking Statements**

Certain statements in this press release may constitute "forward-looking statements" within the meaning of the federal securities laws, including, but not limited to, statements regarding: Apogee's plans for its current and future product candidates and programs; the anticipated timing of its clinical trials, including the Phase 1b in asthma, APEX 52-week Part A in AD, APEX 16-week Part B in AD, and APG279 Phase 1b head-to-head readout against DUPIXENT in AD; its planned clinical trial designs; its plans for current and future clinical trials; the potential clinical benefit and half-life, PK profile and dosing regimen, and treatment outcomes of APG777, APG279, APG273, APG990, APG333, and APG808, Apogee's other product candidates, including combination therapies, and any other potential programs; its planned business strategies; its expected timing for future pipeline updates and commercialization; and its expectations regarding the time period over which Apogee's capital resources will be sufficient to fund its anticipated operations. Words such as "may," "might," "will," "objective," "intend," "should," "could," "can," "would," "expect," "believe," "design," "estimate," "predict," "potential," "develop," "plan" or the negative of these terms, and similar expressions, or statements regarding intent, belief, or current expectations, are forward-looking statements. While Apogee believes these forward-looking statements are reasonable, undue reliance should not be placed on any such forward-looking statements, which are based on information available to the company on the date of this release. These forward-looking statements are based upon current estimates and assumptions and are subject to various risks and uncertainties (including, without limitation, those set forth in Apogee's filings with the U.S. Securities and Exchange

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![img126220792_0.jpg](img126220792_0.jpg)

Commission (the SEC)), many of which are beyond the company's control and subject to change. Actual results could be materially different. Risks and uncertainties include: global macroeconomic conditions and related volatility, expectations regarding the initiation, progress, and expected results of Apogee's preclinical studies, clinical trials and research and development programs; expectations regarding the timing, completion and outcome of Apogee's clinical trials; the unpredictable relationship between preclinical study results and clinical study results; the timing or likelihood of regulatory filings and approvals; liquidity and capital resources; and other risks and uncertainties identified in Apogee's Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on March 3, 2025, Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed with the SEC on May 12, 2025, Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the SEC on August 11, 2025 and subsequent disclosure documents Apogee may file with the SEC. Apogee claims the protection of the Safe Harbor contained in the Private Securities Litigation Reform Act of 1995 for forward-looking statements. Apogee expressly disclaims any obligation to update or alter any statements whether as a result of new information, future events or otherwise, except as required by law.

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![img126220792_0.jpg](img126220792_0.jpg)

**APOGEE THERAPEUTICS, INC.**

**CONDENSED CONSOLIDATED BALANCE SHEETS**<sup>1</sup>

**(UNAUDITED)**

(In thousands, except share data)

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| | | |
|:---|:---|:---|
|  | **SEPTEMBER 30,**<br>**2025** | **DECEMBER 31,**<br>**2024** |
| **Assets** |  |  |
| Current assets: |  |  |
| &nbsp;&nbsp;&nbsp;Cash and cash equivalents | $107914 | $141789 |
| &nbsp;&nbsp;&nbsp;Marketable securities | 419375 | 378864 |
| &nbsp;&nbsp;&nbsp;Prepaid expenses and other current assets | 12808 | 9060 |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Total current assets | 540097 | 529713 |
| Long-term marketable securities | 61640 | 210416 |
| Property and equipment, net | 6032 | 1959 |
| Right-of-use asset, net | 9646 | 11365 |
| Other non-current assets | 8744 | 498 |
| Total assets | $626159 | $753951 |
| **Liabilities and stockholders' equity** |  |  |
| Current liabilities: |  |  |
| &nbsp;&nbsp;&nbsp;Accounts payable | $376 | $1071 |
| &nbsp;&nbsp;&nbsp;Lease liability | 4079 | 3234 |
| &nbsp;&nbsp;&nbsp;Accrued expenses and other current liabilities | 29592 | 24255 |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Total current liabilities | 34047 | 28560 |
| Long-term liabilities: |  |  |
| &nbsp;&nbsp;&nbsp;Lease liability, net of current | 5774 | 8597 |
| Total liabilities | 39821 | 37157 |
| Stockholders' equity: |  |  |
| &nbsp;&nbsp;&nbsp;Common Stock; $0.00001 par value, 400,000,000 authorized, 60,147,727 issued and 59,315,738 outstanding as of September 30, 2025; 400,000,000 authorized, 59,478,725 issued and 58,062,898 outstanding as of December 31, 2024 | 1 | 1 |
| &nbsp;&nbsp;&nbsp;Additional paid-in capital | 1077681 | 1021794 |
| &nbsp;&nbsp;&nbsp;Accumulated other comprehensive income | 1028 | 915 |
| &nbsp;&nbsp;&nbsp;Accumulated deficit | (492372) | (305916) |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Total stockholders' equity | 586338 | 716794 |
| Total liabilities and stockholders' equity | $626159 | $753951 |

---

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<sup>1</sup> Note that Condensed Consolidated Balance Sheet as of September 30, 2025, excludes the impact of the October 2025 underwritten public equity offering.

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![img126220792_0.jpg](img126220792_0.jpg)

**APOGEE THERAPEUTICS, INC.**

**CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS**

**(UNAUDITED)**

(In thousands)

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| | | | | |
|:---|:---|:---|:---|:---|
|  | **THREE MONTHS ENDED SEPTEMBER 30,** | **THREE MONTHS ENDED SEPTEMBER 30,** | **NINE MONTHS ENDED SEPTEMBER 30,** | **NINE MONTHS ENDED SEPTEMBER 30,** |
|  | **2025** | **2024** | **2025** | **2024** |
| Operating expenses: |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Research and development | $54178 | $45714 | $156268 | $107636 |
| &nbsp;&nbsp;&nbsp;General and administrative | 17100 | 12972 | 51271 | 33353 |
| &nbsp;&nbsp;&nbsp;Total operating expenses | 71278 | 58686 | 207539 | 140989 |
| Loss from operations | (71278) | (58686) | (207539) | (140989) |
| Other income, net: |  |  |  |  |
| &nbsp;&nbsp;&nbsp;Interest income, net | 6318 | 9668 | 21299 | 26061 |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Total other income, net | 6318 | 9668 | 21299 | 26061 |
| Net loss before taxes | (64960) | (49018) | (186240) | (114928) |
| &nbsp;&nbsp;&nbsp;Provision for income taxes | (61) |  | (216) |  |
| Net loss after taxes | $(65021) | $(49018) | $(186456) | $(114928) |

---

**Investor Contact:**

Noel Kurdi

VP, Investor Relations

Apogee Therapeutics, Inc.

Noel.Kurdi@apogeetherapeutics.com

**Media Contact:**

Dan Budwick

1AB Media

dan@1abmedia.com

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## Exhibit 99.2

![img127144313_0.jpg](img127144313_0.jpg)

**Apogee Therapeutics Announces Positive Interim Phase 1 Results from Healthy Volunteer Trial of APG333, its Novel Half-Life Extended TSLP Antibody** 

*Interim Phase 1 results for APG333 exceeded trial objectives, demonstrated a half-life of approximately 55 days, and suppressed key biomarkers for 6 months following a single dose, supporting potential 3- and 6- month dosing*

*Results support development of a quarterly or less frequently dosed co-formulation of APG273 (APG777+APG333) for respiratory indications*

*APG333 was well tolerated across all cohorts with doses of up to 1,000 mg* 

**SAN FRANCISCO and BOSTON, November 10, 2025** -- Apogee Therapeutics, Inc. (Nasdaq: APGE), a clinical-stage biotechnology company advancing optimized, novel biologics with potential for best-in-class profiles in the largest inflammatory and immunology (I&I) markets, today announced positive interim Phase 1 results from its first-in-human study of APG333, which demonstrated data supporting potential 3- and 6-month dosing based on a half-life of approximately 55 days across doses tested. Additionally, APG333 was well tolerated across all cohorts, with doses up to 1,000 mg.

"Today's positive results show that our engineered antibody approach continues to deliver durable activity, which may enable less frequent dosing versus currently available agents, potentially improving adherence and outcomes for patients. This milestone represents another important step forward for our pipeline in the evolution of I&I treatments," said Michael Henderson, M.D., Chief Executive Officer of Apogee. "The extended PK and favorable tolerability profile of APG333 underscores Apogee's potential to advance a quarterly or better dosing combination of APG777 and APG333, designed to address key drivers of respiratory diseases more broadly than a monotherapy.""

The APG333 Phase 1 clinical trial was designed as a double-blind, placebo-controlled, first-in-human, single-ascending dose study in healthy volunteers. It evaluated the safety, tolerability and PK of APG333 in 32 healthy adults across four cohorts. Key results include:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•APG333 demonstrated an optimized PK profile, including a half-life of approximately 55 days, supporting potential for APG273 (APG777+APG333) every 3- month or better dosing.

oKey biomarkers of eosinophils and IL-5 showed depth of suppression in line with TSLP analogs and durability out to 6 months (limit of available follow up).

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;•APG333 was well tolerated across the four cohorts, with doses of up to 1,000 mg.

oThe most common treatment-emergent adverse events (TEAEs) occurring in ≥10% of APG333 treated participants were headache and upper respiratory tract infection.

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oTEAEs were generally mild and self-limited and there were no dose dependent trends in TEAEs seen.

oThere were no Grade 3 TEAEs related to study drug or serious adverse events. No adverse events led to study discontinuation.

"We are encouraged by these initial results, which further highlight the potential of TSLP inhibition, a clinically validated target that plays an important role in promoting immune cell recruitment and activation," said Carl Dambkowski, M.D., Chief Medical Officer of Apogee. "APG333's PK profile supports the potential for dosing two to four times a year, a significant advancement over the current standard of care. These data unlock our combination of APG777 and APG333, which together demonstrated suppression of complementary pathways implicated in obstructive airway disease and may enable quarterly or less frequent dosing, expanding options for patients with limited available treatments."

**About APG333**

APG333 is a novel, SQ extended half-life mAb targeting TSLP, an epithelial cell-derived cytokine that has emerged as an attractive, clinically validated target for the treatment of I&I indications because the target plays an important role in promoting immune cell recruitment and activation. In addition, a TSLP-targeting mAb may be used in combination with other mAbs for potentially greater efficacy in broader populations. TSLP inhibition has been clinically validated, with one approved product on the market for the treatment of severe asthma without biomarker or phenotype restrictions.

**About Apogee** 

Apogee Therapeutics is a clinical-stage biotechnology company advancing optimized, novel biologics with potential for best-in-class profiles in the largest I&I markets, including for the treatment of Atopic Dermatitis (AD), asthma, Eosinophilic Esophagitis (EoE), Chronic Obstructive Pulmonary Disease (COPD), and other I&I indications. Apogee's antibody programs are designed to overcome limitations of existing therapies by targeting well-established mechanisms of action and incorporating advanced antibody engineering to optimize half-life and other properties. APG777, the company's most advanced program, is being initially developed for the treatment of AD, which is the largest and one of the least penetrated I&I markets. With four validated targets in its portfolio, Apogee is seeking to achieve best-in-class profiles through monotherapies and combinations of its novel antibodies. Based on a broad pipeline and depth of expertise, the company believes it can deliver value and meaningful benefit to patients underserved by today's standard of care. For more information, please visit https://apogeetherapeutics.com.

**Forward Looking Statements**

Certain statements in this press release may constitute "forward-looking statements" within the meaning of the federal securities laws, including, but not limited to, statements regarding: Apogee's plans for its current and future product candidates and programs; its planned clinical trial designs; its plans for current and future clinical trials; and the potential clinical benefit and half-life, PK profile and

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dosing regimen, and treatment outcomes of APG273 (APG777+APG333). Words such as "may," "might," "will," "objective," "intend," "should," "could," "can," "would," "expect," "believe," "design," "estimate," "predict," "potential," "develop," "plan" or the negative of these terms, and similar expressions, or statements regarding intent, belief, or current expectations, are forward-looking statements. While Apogee believes these forward-looking statements are reasonable, undue reliance should not be placed on any such forward-looking statements, which are based on information available to the company on the date of this release. These forward-looking statements are based upon current estimates and assumptions and are subject to various risks and uncertainties (including, without limitation, those set forth in Apogee's filings with the U.S. Securities and Exchange Commission (the SEC)), many of which are beyond the company's control and subject to change. Actual results could be materially different. Risks and uncertainties include: global macroeconomic conditions and related volatility, expectations regarding the initiation, progress, and expected results of Apogee's preclinical studies, clinical trials and research and development programs; expectations regarding the timing, completion and outcome of Apogee's clinical trials; the unpredictable relationship between preclinical study results and clinical study results; the timing or likelihood of regulatory filings and approvals; liquidity and capital resources; and other risks and uncertainties identified in Apogee's Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on March 3, 2025, Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the SEC on August 11, 2025, and subsequent disclosure documents Apogee may file with the SEC. Apogee claims the protection of the Safe Harbor contained in the Private Securities Litigation Reform Act of 1995 for forward-looking statements. Apogee expressly disclaims any obligation to update or alter any statements whether as a result of new information, future events or otherwise, except as required by law.

**Investor Contact**:

Noel Kurdi

VP, Investor Relations

Apogee Therapeutics, Inc.

noel.kurdi@apogeetherapeutics.com

**Media Contact:**

Dan Budwick

1AB Media

dan@1abmedia.com

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