APVO

EX-99.1

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EX-99.1

EX-99.1

Exhibit 99.1

Aptevo Therapeutics Provides a 1Q26 Business Update; RAINIER on Track for 2026 Completion and Phase 2 Dose Selection

Mipletamig continues to perform, delivers 87% clinical benefit and 81% remission in frontline AML, with no CRS in frontline patients

Executive leadership transition complete. Jeff Lamothe appointed CEO; Marvin White assumes Executive Chair

$60 million equity line of credit enhances financial flexibility and extends access to capital through achievement of key catalysts into 2029

SEATTLE, WA – May 13, 2026 – Aptevo Therapeutics Inc. (Nasdaq: APVO), a clinical-stage biotechnology company focused on developing novel immune-oncology therapeutics based on its proprietary ADAPTIR™ and ADAPTIR-FLEX™ platform technologies, today provided a business update.

“Aptevo is entering a defining period as a company, supported by growing clinical momentum, a committed leadership team, and a pipeline with the potential to create significant long-term value,” said Jeff Lamothe, President and Chief Executive Officer of Aptevo. “Mipletamig continues to generate compelling frontline AML data, combining strong remission activity with a differentiated safety profile with the potential as an important addition to standard-of-care therapy. At the same time, we are continuing to advance our next generation of multispecific immunotherapy programs, including our emerging trispecific candidates, which are designed to address complex solid tumors through differentiated mechanisms and targeted immune modulation. We believe our ADAPTIR and ADAPTIR-FLEX platforms position Aptevo to expand into multiple high-value areas of oncology innovation. With meaningful clinical and strategic milestones ahead, financial flexibility to support execution, and increasing validation of multispecific approaches throughout the industry, we believe we are building from an increasingly strong foundation for future growth and value creation.”

RAINIER trial on track for completion and Phase 2 dose selection by year end.

• Mipletamig continues to generate strong data in frontline acute myeloid leukemia (AML) in combination with venetoclax + azacitidine. Across 31 evaluable patients (includes data through RAINIER Cohort 5, plus 4 patients from the previously completed dose expansion trial), the data has demonstrated continued efficacy, including:

• 87% clinical benefit rate* demonstrates broad anti-leukemia activity and blast reduction across response categories

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• 81% CR or CRi (remission), compared to 66.4% in the Phase 3 VIALE-A trial**

• 65% achieved CR (complete remission), compared to 37% in the Phase 3 VIALE-A trial**

• No cytokine release syndrome (CRS), a common and often dose-limiting toxicity associated with similar therapies, has been observed in frontline patients to date

The data also show that 52% of patients who achieved CR/CRi had blast reductions that reached the important measurable residual disease-negative level, a result that is typically associated with stronger, more durable responses.

As the dataset continues to expand, efficacy and safety outcomes continue to deliver favorable results, further supporting mipletamig’s potential in the frontline setting.

*Clinical benefit rate: complete remission (CR), complete remission with incomplete hematologic recovery (CRi), and partial remission (PR)

**Phase 3 VIALE-A trial evaluating venetoclax plus azacitidine in frontline intent-to-treat AML patients who were ineligible for intensive induction chemotherapy, the reported composite CR/CRi rate was 66.4%, and the CR rate was 37% (DiNardo et al., New England Journal of Medicine, 2020).

Completed Leadership Transitions; Company Poised for a Defining Year Aptevo entered 2026 with purposeful momentum, highlighted by a planned executive leadership transition designed to support the company’s next phase of growth. Jeff Lamothe was appointed President and Chief Executive Officer, while Marvin White transitioned to Executive Chair. The move reflects continuity in strategy while positioning the organization for focused execution across clinical development, capital strategy, and long-term value creation.

Q1 2026 Cash Position

Aptevo had cash and cash equivalents totaling $14.5 million as of March 31, 2026. During the first quarter of 2026, the company raised $0.9 million, net, under the company’s Standby Equity Purchase Agreements (SEPAs) with Yorkville. For additional APVO financial information and complete access to the company’s filings, click here.

Enhanced Financial Flexibility Supports Upcoming Catalysts During the quarter, Aptevo secured a $60 million SEPA, providing meaningful access to capital and extending financial flexibility as the company advances toward planned milestones. Management believes the facility better positions Aptevo to execute strategically, support ongoing development programs, and approach future opportunities from a position of greater s

EX-99.1

2 apvo-ex99_1.htm

EX-99.1

EX-99.1

Exhibit 99.1

Aptevo Provides State of the Business Report and 2025 Financial Results

Latest mipletamig data delivers 86% clinical benefit rate with no cytokine release syndrome in 28 frontline AML patients, supporting its potential to enhance standard-of-care combination therapy

Company expands CD3 pipeline and introduces first trispecific drug candidates

SEATTLE, WA – March 26, 2026 – Aptevo Therapeutics Inc. (Nasdaq: APVO), a clinical-stage biotechnology company developing novel immune-oncology therapeutics based on its proprietary ADAPTIR and ADAPTIR-FLEX platform technologies, today reported financial results for the year ended December 31, 2025 and provided a business update highlighting recent clinical progress, pipeline expansion and capital strategy.

“2025 was a year of meaningful progress across our clinical programs, pipeline strategy and capital position,” said Marvin White, President and Chief Executive Officer of Aptevo Therapeutics. “Most importantly, recently reported mipletamig data continue to demonstrate encouraging remission outcomes together with a favorable safety profile, including no cytokine release syndrome observed in frontline patients treated to date. These results support the potential for mipletamig to enhance frontline AML treatment alongside existing standard-of-care therapy.”

White continued, “During the year we also expanded our CD3 pipeline, introduced our first trispecific programs and strengthened our access to capital to support continued execution. As I transition into the role of Executive Chair and Jeff Lamothe assumes the responsibilities of President and Chief Executive Officer, I am confident in the Company’s ability to build on this momentum.”

Highlights

Aptevo entered 2026 with momentum:

• Mipletamig Clinical Performance: Mipletaming in triplet combination therapy continues to outperform standard of care ven/aza1 in unfit frontline patients with acute myeloid leukemia (AML). This further validates a differentiated safety profile, including no cytokine release syndrome in frontline patients, suggesting it is additive to the current standard of care

• Expanded CD3 portfolio: the addition of three new multispecific candidates, leveraging the Company’s proprietary application of its differentiated CRIS7-derived CD3 binding domain, including the introduction of its first two trispecific assets

o These additions emphasize the breadth and modularity of the ADAPTIR and ADAPTIR-FLEX platforms and position the Company to address a wider range of tumor targets and combination strategies across immune-oncology

• Strengthened Financial Capacity: In 2026, the Company established a $60 million equity line facility, providing additional access to capital, subject to market conditions and the Company’s

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capital deployment strategy. If fully utilized, this facility, together with current resources, is expected to support operations into 2029.

Encouraging Frontline AML Data

Updated interim results from 28 evaluable frontline AML patients2 treated with mipletamig in combination with ven/aza demonstrate an emerging clinical profile that is additive in combination with standard of care. The triplet regimen delivered an 86% clinical benefit rate, including a 79% CR/CRi (vs. 66% )1 remission rate and a 61% complete remission rate (vs.37%)1.

Among patients achieving remission, 55% reached measurable residual disease–negative status. Notably, 35% of remissions occurred in patients with TP53 mutations, a high-risk biomarker typically associated with poor prognosis.

Importantly, no cytokine release syndrome has been observed in frontline patients treated to date. Outcomes from the mipletamig triplet compare favorably with historical results reported for the ven/aza doublet and support the potential for mipletamig to enhance frontline AML therapy for older and/or unfit patients.

“Mipletamig continues to demonstrate encouraging remission outcomes together with a consistently favorable safety profile,” said Dirk Huebner, M.D., Chief Medical Officer of Aptevo Therapeutics. “The absence of cytokine release syndrome in frontline patients underscores the potential advantage of our differentiated CD3 design in combination treatment settings.”

Huebner added, “Four patients treated to date have proceeded to allogeneic stem cell transplant, representing the most favorable treatment outcome in AML and an uncommon achievement in the older and/or unfit frontline population.”

A Differentiated CD3 Platform

During 2025 Aptevo expanded its CD3 portfolio with three new multispecific candidates, including the Company’s first two trispecific drug candidates designed to address complex solid tumor microenvironments.

All programs leverage Aptevo’s proprietary CRIS-7–derived CD3 binding domain, designed to promote targeted T-cell activation while reducing systemic immune overstimulation. Clinical experience with mipletamig, now evaluated in mo

8-K

0001671584false00016715842025-11-062025-11-06

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): November 06, 2025

APTEVO THERAPEUTICS INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware

001-37746

81-1567056

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

2401 4th Avenue Suite 1050

Seattle, Washington

98121

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s Telephone Number, Including Area Code: (206) 838-0500

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, $0.001 par value

APVO

The Nasdaq Stock Market LLC

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 November 6, 2025, Aptevo Therapeutics Inc. (the “Company”) issued a press release announcing its financial results for the period ended September 30, 2025. A copy of the press release is attached hereto as Exhibit 99.1 and incorporated herein by reference.

The information in this report, including the exhibit hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Act of 1934, as amended, or otherwise subject to the liabilities of that section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained herein and in the accompanying exhibit shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission (the “SEC”) made by the Company, whether made before, on or after the date hereof, regardless of any general incorporation language in such filing, except as shall be expressly set forth by specific reference in such filing. Item 9.01 Financial Statements and Exhibits. (d) Exhibits

Exhibit No.

Description

99.1

Press Release dated November 6, 2025.

104

Cover Page Interactive Data File (embedded within the Inline XBRL document)

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.

APTEVO THERAPEUTICS INC.

Date:

November 6, 2025

By:

/s/ Marvin L. White

Marvin L. White President and Chief Executive Officer