ALX Oncology Reports Second Quarter 2023 Financial Results and Provides Clinical Program Update

Advancing Phase 2/3 ASPEN-06 gastric cancer trial with data update expected in Q423

Terminating azacitidine combination development programs: ASPEN-02 in MDS and ASPEN-05 in AML

Continuing focus on combinations with anti-cancer antibodies, antibody-drug conjugates, and PD-1/PD-L1 immune checkpoint inhibitors

SOUTH SAN FRANCISCO, Calif., August 10, 2023 (GLOBE NEWSWIRE) -- ALX Oncology Holdings Inc., (“ALX Oncology” or “the Company”) (Nasdaq: ALXO), an immuno-oncology company developing therapies that block the CD47 immune checkpoint pathway, today reported financial results for the second quarter ended June 30, 2023, and provided an update on the Company’s portfolio of clinical programs in development.

During the second quarter, ALX Oncology continued to advance evorpacept’s mid-stage clinical development programs highlighted by ASPEN-06 in HER2-positive gastric cancer which is on track to report data in Q423. In addition, the Company is transitioning its development strategy to purely focus on combinations with anti-cancer antibodies, antibody-drug conjugates (“ADCs”), and PD-1/PD-L1 immune checkpoint inhibitors. While well tolerated, the Company is terminating the ASPEN-02 program which evaluated evorpacept in combination with azacitidine for myelodysplastic syndromes (“MDS”), as the evorpacept combination did not substantially improve upon the historical activity of azacitidine alone. Patients currently on trial may continue in the study and the Company plans to present the full data set from the forty-five subjects at an upcoming scientific conference. Moreover, based on the initial results of ASPEN-02 and the close connection between the mechanism of action with azacitidine in MDS and acute myeloid leukemia (“AML”), the Company will also terminate the ASPEN-05 program in AML and will not initiate a Phase 1b dose optimization clinical evaluation of evorpacept in combination with azacitidine and venetoclax. Based upon this decision, resources originally earmarked for these trials will be allocated to support the Company’s ongoing programs evaluating combinations with anti-cancer antibodies and PD-1/PD-L1 immune checkpoint inhibitors.

Rational Design and Dual Development Pillars

Rationally engineered with an inactive Fc effector function, evorpacept’s clinical data to date has demonstrated a substantially improved safety profile over other anti-CD47 molecules in the clinic with an active Fc (i.e., binding the Fc gamma receptor on macrophages). This superior safety profile allows us to dose higher with minimal overlapping toxicity in the combination treatment setting. CD47 expressed on cancer cells binds to its receptor SIRP alpha, which is predominantly expressed on two cell types: macrophages and dendritic cells. ALX Oncology will focus evorpacept development with the standard-of-care agents as originally designed revolving around these two cell types, including:

Anti-cancer antibodies (the “don’t eat me” signal): evorpacept enables Fc-mediated antibody-dependent phagocytosis by macrophages in combination with anti-cancer antibodies (e.g., Herceptin®) with an active Fc domain, which is otherwise impaired by CD47 expression on cancer cells binding to SIRP alpha on macrophages. This same mechanism of action applies to ADCs.

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PD-1/PD-L1 immune checkpoint inhibitors (the “don’t activate T-cell” signal): evorpacept enables T-cell activation by dendritic cells that are constitutively inhibited by CD47 expression on cancer cells binding to SIRP alpha on dendritic cells. Activated dendritic cells present neoantigens to T-cells that once activated will kill cancer cells when the PD-1/PD-L1 inhibitory interaction is blocked by T-cell checkpoint inhibitors.

“The second quarter proved to be an important period of progress as we advanced key programs and refined the development strategy for evorpacept, our platform asset,” commented Dr. Jaume Pons, Founder, President and Chief Executive Officer of ALX Oncology. “While the efficacy results from ASPEN-02 do not warrant further sponsored clinical evaluation in MDS, we remain steadfast in our conviction that the primary mechanism of action of evorpacept is unique compared to other CD47 blockers when combined with anti-cancer antibodies, ADCs, or immune checkpoint inhibitors. Evorpacept was rationally designed with an inactive Fc domain for improved safety and synergies with anti-cancer antibody-based regimens like Herceptin, antibody-drug conjugates, as well as PD-1/PD-L1 immune checkpoint inhibitors like KEYTRUDA® (pembrolizumab). Moving forward the Company will conduct clinical trials where this mechanistic rationale is fulfilled. We move into the second half of 2023 with sufficient funding and with the momentum needed to advance our pipeline of therapeutic candidates led by ASPEN-06, a randomized Phase 2 trial combining Herceptin, CYRAMZA® and paclitaxel for the treatment of patients with HER2-positive gastric or gastroesophageal junction (“GEJ”) cancer.”

Clinical Highlights for Evorpacept

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Upcoming Milestones in 2023

Second Quarter 2023 Financial Results

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About ALX Oncology

ALX Oncology is a publicly traded, clinical-stage immuno-oncology company focused on helping patients fight cancer by developing therapies that block the CD47 immune checkpoint inhibitor and bridge the innate and adaptive immune system. ALX Oncology’s lead product candidate, evorpacept, is a next generation CD47 blocking therapeutic that combines a high-affinity CD47 binding domain with an inactivated, proprietary Fc domain. Evorpacept has demonstrated promising clinical responses across a range of hematologic and solid malignancies in combination with a number of leading anti-cancer antibodies. ALX Oncology is currently focusing on combining evorpacept with anti-cancer antibodies, antibody-drug conjugates, and PD-1/PD-L1 immune checkpoint inhibitors.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements that involve substantial risks and uncertainties. Forward-looking statements include statements regarding future results of operations and financial position, business strategy, product candidates, planned preclinical studies and clinical trials, results of clinical trials, research and development costs, regulatory approvals, timing and likelihood of success, plans and objects of management for future operations, as well as statements regarding industry trends. Such forward-looking statements are based on ALX Oncology’s 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 Oncology’s actual results, performance or achievements to be materially different from those expressed or implied by the forward-looking statements. These and other risks are described more fully in ALX Oncology’s filings with the Securities and Exchange Commission (“SEC”), including ALX Oncology’s Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and other documents ALX Oncology 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.

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ALX ONCOLOGY HOLDINGS INC.

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Use of Non-GAAP Financial Measures

We supplement our consolidated financial statements presented on a GAAP basis by providing additional measures which may be considered “non-GAAP” financial measures under applicable SEC rules. We believe that the disclosure of these non-GAAP financial measures provides our investors with additional information that reflects the amounts and financial basis upon which our management assesses and operates our business. These non-GAAP financial measures are not in accordance with generally accepted accounting principles and should not be viewed in isolation or as a substitute for reported, or GAAP, net loss, and are not a substitute for, or superior to, measures of financial performance performed in conformity with GAAP.

“Non-GAAP net loss” is not based on any standardized methodology prescribed by GAAP and represents GAAP net loss adjusted to exclude stock-based compensation expense and accretion of term loan discount and issuance costs. Non-GAAP financial measures used by ALX Oncology may be calculated differently from, and therefore may not be comparable to, non-GAAP measures used by other companies.

Investor Contact:

Peter Garcia

Chief Financial Officer, ALX Oncology

(650) 466-7125 Ext. 113

peter@alxoncology.com

Malini Chatterjee, Ph.D.

Blueprint Life Science Group

mchatterjee@bplifescience.com

Media Contact:

Karen Sharma

MacDougall

(781) 235-3060

alx@macdougall.bio

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