Aptevo Therapeutics Presents New Data on Enhanced Features of Its Next Generation ADAPTIR™ Bispecific Platform at the World Bispecific Summit

SEATTLE, Oct. 02, 2017 (GLOBE NEWSWIRE) -- Aptevo Therapeutics Inc. (Nasdaq:APVO), a biotechnology company focused on developing novel immuno-oncology and hematology therapeutics, today announced that new information on the Company’s proprietary next generation ADAPTIR™ protein therapeutic platform was presented at the 8th Annual World Bispecific Summit in Boston, MA, September 26-28, 2017. 

In a presentation entitled, “ADAPTIR™ Platform: Rapid Development of Novel Protein Therapeutics,” Dr. Peter Pavlik, Principal Scientist at Aptevo, presented a comprehensive overview of Aptevo’s next generation ADAPTIR platform, highlighting improvements that have led to the development of new ADAPTIR candidates with increased stability, superior manufacturability and antibody expression levels, and an extended half-life of up to 12.5 days in rodents. 

In his overview, Dr. Pavlik describes the expansion of Aptevo’s ADAPTIR platform into several different mechanisms of action, including, T-cell engagers targeting CD3; a bispecific targeting the costimulatory receptor 41BB and a solid tumor antigen; and a bispecific that targets a cytokine to specific cells via an ADAPTIR platform.  This evolution highlights the flexible and versatile nature of the ADAPTIR platform and its utility in generating multiple bispecific candidates.

These attributes have been demonstrated with Aptevo’s next generation lead bispecific T-cell engager, APVO436, which simultaneously targets CD123 (a cell surface receptor highly expressed in several hematological malignancies) and CD3 (a T-cell co-receptor that promotes cytotoxicity.)  Data from preclinical studies of APVO436 show that it:

  • Potently and selectively induces tumor-specific immune responses and T-cell mediated cytotoxicity in vitro and in vivo
  • Has an antibody-like serum half-life in mice of up to 12.5 days – significantly longer than first generation ADAPTIR candidates and other bispecific candidates in development
  • Induces potent, dose-dependent T-cell mediated lysis (killing) of CD123-expressing acute myelogenous leukemia (AML) cell lines, accompanied by target-specific T-cell activation and proliferation
  • Possess low (nM) binding affinity; binds with high affinity to human and cynomolgus CD123-expressing cells with EC50 values in the low nanomolar range
  • Dose-dependently inhibits tumor growth and significantly prolongs survival compared to vehicle-treated animals in a Xenograft tumor model of AML

“Our data on APVO436 confirm the important advances we have made with our next generation ADAPTIR candidates, specifically improved stability, half-life, activity and manufacturability – all critical attributes for commercialization,” said Jane Gross, Ph.D., Senior Vice President and Chief Scientific Officer.  “We have also reduced sequences that could lead to immunogenicity in the clinic.  Our next generation candidates, like APVO436, are designed to be delivered by intravenous dosing.  With two ADAPTIR candidates currently in clinical development, and a broad portfolio of bispecifics advancing in preclinical development, Aptevo has a rich pipeline of assets in the emerging field of targeted antibody therapeutics.”

ADAPTIR Bispecific Antibody Platform: Differentiating Characteristics

  • Unique Homodimer Structure - simplifies candidate generation; facilitates rapid substitution of target binding domains to evaluate numerous candidates simultaneously
  • Bivalent for Both Binding Domains - increases the avidity and potency of ADAPTIR candidates
  • Unique IgG Fc ‘Backbone’ - extends the half-life of ADAPTIR molecules (up to ~12.5 days in rodents)
  • Antibody-like Production Processes – demonstrated capability to produce up to 2.0g/L comparable to traditional antibody manufacturing processes
  • Improved Yield and Cost of Goods - use of a single gene and ease of CHO cell line production enhances ADAPTIR bispecific manufacturing productivity

ADAPTIR Clinical and Preclinical Portfolio:

  • APVO414 – a bispecific ADAPTIR candidate, currently in Phase 1 development, targeting prostate specific membrane antigen (PSMA), an enzyme that is expressed on the surface of prostate cancer cells, and, CD3, a component of the T cell receptor complex expressed on all T cells.  APVO414 redirects T cells to specifically kill PSMA expressing tumors and is being developed for metastatic castration-resistant prostate cancer, which is advanced prostate cancer that has spread to other organs and no longer responds to hormone blocking therapies.
  • Otlertuzumab – a monospecific ADAPTIR candidate currently in Phase 2 development for the treatment of chronic lymphocytic leukemia (CLL).  Data from a Phase 2 clinical trial evaluating otlertuzumab in combination with bendamustine, compared to bendamustine alone, demonstrated a significant increase in median progression free survival for the combination, from approximately 10 to 16 months.
  • APVO436 – a bispecific ADAPTIR candidate currently in preclinical development targeting CD123, a cell surface receptor highly expressed on several hematological malignancies and CD3, a component of the T-cell receptor. APVO436 engages T cells to kill tumor cells.
  • ALG.APV-527 – a bispecific antibody candidate, partnered with Alligator Bioscience, featuring a novel mechanism of action designed to simultaneously target 4-1BB (CD137) and an undisclosed tumor antigen.  4-1BB, a costimulatory receptor on T cells, is known to enhance the immune response to cancer through activation of tumor-specific T cells and is believed to be a promising target for new immunotherapeutic approaches. ALG.APV-527 could potentially have utility in the treatment of a broad spectrum of cancers over-expressing the tumor antigen, including breast, cervical, non-small-cell-lung, prostate, renal, gastric, colorectal and bladder cancers.
  • APVO210 – a bispecific ADAPTIR preclinical candidate with a novel mechanism of action based on targeted cytokine delivery.  APVO210 is composed of a humanized anti-CD86 antibody fused with a modified form of IL-10 that specifically induces IL-10 signaling on antigen presenting cells, but not on lymphoid populations. APVO210 functions by suppressing immune responses and inducing certain tolerogenic responses and therefore may have potential benefit for the treatment of autoimmune and inflammatory diseases.
  • ROR1 Bispecific – a proof-of-concept bispecific candidate targeting ROR1, an antigen found on several solid tumors and hematologic, or blood-related malignancies.  Initial preclinical data demonstrate redirected T cell killing of tumors expressing ROR1 in vitro and in vivo in animal models.

About Aptevo Therapeutics Inc.

Aptevo Therapeutics Inc. is a clinical-stage biotechnology company focused on novel oncology and hematology therapeutics to meaningfully improve patients’ lives.  Aptevo has a commercial product, IXINITY®, approved and marketed in the United States for the treatment of Hemophilia B, and a versatile core technology – the ADAPTIR™ modular protein technology platform capable of generating highly-differentiated bispecific antibodies with unique mechanisms of action to treat cancer or autoimmune diseases.  Aptevo has two ADAPTIR antibody candidates currently in clinical development and a broad pipeline of novel investigational-stage bispecific antibody candidates focused in immuno-oncology and autoimmune disease and inflammation. For more information, please visit www.aptevotherapeutics.com

Safe Harbor Statement

This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Any statements, other than statements of historical fact, including, without limitation, statements regarding potential milestone payments, Aptevo’s outlook, financial performance or financial condition, Aptevo’s technology and related pipeline, collaboration and partnership opportunities, commercial portfolio, and any other statements containing the words “believes,” “expects,” “anticipates,” “intends,” “plans,” “forecasts,” “estimates,” “will” and similar expressions are forward-looking statements. These forward-looking statements are based on Aptevo’s current intentions, beliefs and expectations regarding future events. Aptevo cannot guarantee that any forward-looking statement will be accurate. Investors should realize that if underlying assumptions prove inaccurate or unknown risks or uncertainties materialize, actual results could differ materially from Aptevo’s expectations. Investors are, therefore, cautioned not to place undue reliance on any forward-looking statement. Any forward-looking statement speaks only as of the date of this press release, and, except as required by law, Aptevo does not undertake to update any forward-looking statement to reflect new information, events or circumstances.

There are a number of important factors that could cause Aptevo’s actual results to differ materially from those indicated by such forward-looking statements, including possible negative effects on our business operations, assets or financial results as a result of the closing of the transaction;; a deterioration in Aptevo’s business or prospects; the parties may be unable to achieve the anticipated benefits of the transaction; adverse developments in the U.S. or global capital markets, credit markets or economies generally; and changes in regulatory, social and political conditions. Additional risks and factors that may affect results are set forth in Aptevo’s filings with the Securities and Exchange Commission, including its most recent Annual Report on Form 10-K, as filed on March 31, 2017, and its subsequent reports on Form 10-Q and current reports on Form 8-K. The foregoing sets forth many, but not all, of the factors that could cause actual results to differ from Aptevo’s expectations in any forward-looking statement.

For Further Information:

Aptevo Therapeutics
Stacey Jurchison
Senior Director, Investor Relations and Corporate Communications