GlobeNewswire Inc | Mar 4, 2021 04:05PM EST

March 04, 2021

-- Companies will combine their unique scientific and technical expertise to develop a first-in-class anti-SIRP antibody conjugated to TLR9 agonist (SIRP TRAAC) that delivers targeted immune activation -- ALX expands anti-cancer therapeutics pipeline targeting the CD47 checkpoint pathway -- Collaboration extends Tallacs pipeline of next generation immunotherapies derived from its Toll-like Receptor Agonist Antibody Conjugate (TRAAC) platform -- ALX Oncology to HostConference Callon March 5 at 8:30 a.m. EST

BURLINGAME, Calif., March 04, 2021 (GLOBE NEWSWIRE) -- ALX Oncology Holdings Inc. (ALX Oncology) (Nasdaq: ALXO), a clinical-stage immuno-oncology company developing therapies that block the CD47 checkpoint pathway, and Tallac Therapeutics, Inc. (Tallac), a privately held biopharmaceutical company harnessing the power of innate and adaptive immunity to fight cancer, today announced a collaboration to jointly develop, manufacture, and commercialize a novel class of cancer immunotherapeutics. Under the terms of the agreement, ALX Oncology and Tallac will share equally in the cost of research and development and any profits or losses incurred.

The collaboration builds on ALX Oncologys expertise in developing therapies that block the CD47 checkpoint pathway and expands its immuno-oncology pipeline. The collaboration also extends Tallacs pipeline of next generation immunotherapies derived from its novel Toll-like Receptor Agonist Antibody Conjugate (TRAAC) platform. The companies will leverage their respective scientific and technical expertise to advance an anti-SIRP antibody conjugated to a Toll-like receptor 9 (TLR9) agonist for targeted activation of both the innate and adaptive immune systems.

We are excited to partner with ALX Oncology in the development of next-generation breakthrough cancer immunotherapies, said Hong I. Wan, Ph.D., President, Chief Executive Officer and co-founder of Tallac. TLR9 agonists are a class of immunotherapy that generate both innate and adaptive immune responses which may produce robust and durable anti-cancer immunity for patients with advanced-stage cancers. While intratumoral TLR9 agonists have clinically validated this pathway, systemic administration has been unsuccessful, limiting clinical utility in broader patient populations. With Tallacs TRAAC technology, we now have a way to target this pathway systemically, which could expand the clinical benefit to a much broader patient population. To date, we have generated promising preclinical data with multiple TRAAC molecules that demonstrates the potential of this pathway. The goal of our collaboration with ALX Oncology is to advance SIRP TRAAC, a systemically delivered TLR9 agonist targeting dendritic cells via SIRP receptors, enabling a powerful innate and adaptive anti-tumor immune response.

Collaborating with Tallac and their novel TRAAC platform broadens ALX Oncologys therapeutic strategies to activate the innate immune system and SIRP TRAAC complements our lead product candidate, ALX148, said Jaume Pons, Ph.D., Founder, President and Chief Executive Officer of ALX Oncology. While ALX148 is an antagonistic molecule designed to maximize the activity of a wide array of anticancer agents by the blockade of the CD47 myeloid checkpoint, SIRP TRAAC is an agonistic molecule that directly activates dendritic cells and enables a coordinated innate and adaptive immune response against cancer. Since SIRP is expressed on both dendritic cells and a range of tumor types, SIRP TRAAC may enable an effective immune activation response in advanced cancer settings. We are excited about this potentially transformative approach and the possible benefits to patients that are in need of new treatment options.

Conference Call on March 5at 8:30 a.m. EST

ALX Oncology and Tallac will host a conference call on Friday, March 5, 2021 at 8:30 a.m. EST to further discuss the collaboration.

To access the conference call, please dial (844) 467-7655 (local) or (409) 983-9840 (international) at least 10 minutes prior to the start time and refer to conference ID 4117088. Presentation slides will be available to download under News & Events (see Events) in the investors section of the ALX Oncology website atwww.alxoncology.com.

About ALX OncologyALX Oncology is a publicly traded, clinical-stage immuno-oncology company focused on helping patients fight cancer by developing therapies that block the CD47 checkpoint pathway and bridge the innate and adaptive immune system. ALX Oncologys lead product candidate, ALX148, is a next generation CD47 blocking therapeutic that combines a high-affinity CD47 binding domain with an inactivated, proprietary Fc domain. ALX148 has demonstrated promising clinical responses across a range of hematologic and solid malignancies in combination with a number of leading anti-cancer agents. ALX Oncology intends to continue clinical development of ALX148 for the treatment of a range of solid tumor indications as well as MDS and AML. For more information, please visit www.alxoncology.com.

About TallacTallac Therapeutics is a privately held biopharmaceutical company harnessing the power of innate and adaptive immunity to fight cancer. Tallacs pipeline of immunotherapy candidates are derived from the companys novel Toll-like Receptor Agonist Antibody Conjugate (TRAAC) platform to deliver a potent Toll-like receptor (TLR9) agonist (T-CpG) for targeted immune activation via systemic administration. Several TRAAC molecules are in various stages of discovery and preclinical development. For more information, please visit www.tallactherapeutics.com.

Cautionary Note Regarding Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. Such forward-looking statements are based on ALX Oncologys beliefs and assumptions and on information currently available to it on the date of this press release. Forward-looking statements may involve known and unknown risks, uncertainties and other factors that may cause ALX Oncologys actual results, performance or achievements to be materially different from those expressed or implied by the forward-looking statements. These statements include but are not limited to statements regarding the expectations of the collaboration with Tallac and the beneficial characteristics and potential therapeutic effects of SIRP TRAAC. These and other risks are described more fully in ALX Oncologys filings with the Securities and Exchange Commission (SEC), including ALX Oncologys Quarterly Report on Form 10-Q, filed with the SEC on November 12, 2020, and other documents ALX Oncology subsequently files with the SEC from time to time. Except to the extent required by law, ALX Oncology undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

ALX Oncology

Investor Contact:Peter GarciaChief Financial Officer, ALX Oncology(650) 466-7125 Ext. 113peter@alxoncology.com

Argot Partners(212) 600-1902alxoncology@argotpartners.com

Media Contact:Karen SharmaMacDougall(781) 235-3060alx@macbiocom.com

Tallac Therapeutics

Media Contact:Tara CooperThe Grace Communication Group(650) 303-7306tara@gracegroup.us