AltruBio Presents New Positive Data from its Completed Phase 1b Study Evaluating ALTB-168 in Patients with Steroid-Refractory or Treatment-Refractory Acute Graft-Versus-Host-Disease at the 64th ASH Annual Meeting 2022

• Participants with SR-aGVHD disease achieved an ORR of 67% and CR of 17% as measured by best response
• Participants with TR-aGVHD (11 of 12 concomitant ruxolitinib) achieved an ORR of 67% and CR of 25% at Day 28
• Median survival benefits in TR-aGVHD participants compare favorably to historical controls neihulizumab was well tolerated, with similar safety profiles observed when given alone or in combination with ruxolitinib

SAN FRANCISCO, Dec. 10, 2022 (GLOBE NEWSWIRE) -- AltruBio Inc. (“AltruBio” or “the Company”), a clinical stage biotech company dedicated to the development of novel therapeutics for the treatment of immunological diseases with high unmet medical needs, today announced the presentation of new data from its completed Phase 1b clinical trial evaluating ALTB-168 in patients with steroid-refractory (SR-aGVHD) or treatment-refractory (TR-aGVHD) acute graft-versus-host-disease at the 64^th American Society of Hematology (ASH) Annual Meeting, taking place December 10-13, 2022 in New Orleans, La. The data will be presented in a poster by clinical trial investigator, Sameem Abedin, M.D., Assistant Professor, Medical College of Wisconsin, Cancer Center, Froedtert Hospital Medical.

“The promising efficacy, positive safety and tolerability of ALTB-168 is highly encouraging especially in this patient population that has minimal treatment options,” said Dr. Sameem Abedin, M.D., Assistant Professor, Medical College of Wisconsin, Cancer Center, Froedtert Hospital Medical, and a principal investigator participating in the clinical trial. “60% of patients with aGVHD do not respond to corticosteroids as first line treatment, and those that do not respond to any treatment have extremely poor outcomes. There is an urgent need to provide effective and long-lasting treatment options with less side effects.”

Jesse Hall, M.D., Chief Medical Officer of AltruBio added, “We’re pleased to share efficacy data demonstrating that treatment with an immune checkpoint enhancer, ALTB-168, has the potential to improve outcomes in patients with aGVHD. The clinical results in this indication validated the strategy of targeting PSGL-1 to control chronically active T cell-related immunological disorders and restore immune balance. Combined with previous data to date showing that ALTB-168 has been well tolerated in close to 200 patients in four autoimmune diseases, we believe this supports ALTB-168’s first-in-class and clinically validated mechanism of action, derisking our next generation immune checkpoint enhancer ALTB-268. ALTB-268 has the same mechanism of action as ALTB-168 with a greater potency that allows for subcutaneous delivery enabling pursuit of different indications than ALTB-168. We look forward to sharing final data from this trial and preliminary Phase 1 data from ALTB-268 in 2023.”

Key data highlights from the ALTB-168 multiple dose portion of the Phase 1 trial with ruxolitinib from 14 evaluable SR-aGVHD/TR-aGVHD patients to date, include:

• Overall response rate (ORR) of 67% in SR-aGVHD patients (N=12) and a complete response (CR) of 17% as measured by best response
• ORR of 67% in TR-aGVHD patients (11 of 12 concomitant ruxolitinib) at the multiple dose phase of 6-4-4-4 mg/kg – a COR of 25% at Day 28.
• Five SR-aGVHD patients and six TR-aGVHD patients were alive at the end of the study (Visit day 180).
• Corticosteroid reductions were achieved in a significant portion of TR-aGVHD participants
• Safety results were comparable between the SR and TR cohorts

Key data highlights from the ALTB-168 single dose portion of the Phase 1 trial from 13 evaluable SR-aGVHD patients to date, include:

• Best response ORR of 86% (N=7) at the 3 mg/kg dose and a best response ORR of 50% (N=6) at the 6 mg/kg dose – this includes six CRs at the 3 mg/kg dose and two CRs and 1 PR at the 6 mg/kg dose at Day 28.

ASH Presentation Details:

Title: Neihulizumab (ALTB-168) in Patients with Steroid-Refractory Acute Graft-Versus-Host Disease (SR-aGVHD) or Treatment-Refractory Acute Graft-Versus-Host Disease (TR-aGVHD)
Abstract #: 163027
Presenter: Sameem Abedin, M.D., Assistant Professor Medical College of Wisconsin, Cancer Center – Froedtert Hospital Medical

For more information on the 64^th American Society of Hematology (ASH) Annual Meeting and how to register, visit the website.

About ALTB-168
ALTB-168 is an immune checkpoint enhancer that regulates T cell homeostasis. The unique mechanism of action of this agonist antibody maintains T cell homeostasis by preferentially inducing downregulation of activated T cells, potentially sparing resting T cells and early-activated T cells. Because pathogenic T cells involved in inflammatory conditions are usually in an activated and/or auto-activated states, eliminating this population of cells can potentially control inflammation in T cell associated diseases, such as GvHD.

ALTB-168 is being evaluated in a Phase 1 study (NCT03327857) to establish the pharmacokinetics, pharmacodynamics, safety and efficacy profiles in patients with steroid-refractory or treatment refractory acute graft-versus-host disease (SR/TR-aGVHD).

About AltruBio Inc.
AltruBio is a privately held biotechnology company headquartered in San Francisco that is focused on developing novel therapeutics for the treatment of immunological diseases with high unmet medical needs. The company has leveraged its deep understanding of the role PSGL-1 plays as an immune checkpoint regulator protein to develop a platform for T-cell mediated immunological diseases. Its first-generation molecule, ALTB-168, an immune checkpoint agonist antibody targeting PSGL-1/CD162 has achieved proof of mechanism in four autoimmune and inflammatory diseases including ulcerative colitis, steroid refractory acute graft-versus-host disease (SR-aGVHD), psoriatic arthritis, and psoriasis. The next-generation PSGL-1 agonist ALTB-268 is a tetravalent version of ALTB-168 and has demonstrated high potency via the same mechanism, which makes it suitable for subcutaneous administration in the proven indications and is advancing toward IND for multiple autoimmune and inflammatory disorders.

Note on Forward-Looking Statements
Statements made in this news release that are not historical facts are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as expects, believes, intends, and similar expressions are intended to identify forward-looking statements. Actual results may differ materially from those projected in any forward-looking statement. Specifically, there are a number of important factors that could cause actual results to differ materially from those anticipated, such as the Company's ability to raise additional capital, and risks related to the Company's ability to initiate, and enroll patients in, planned clinical trials. You should not place undue reliance on any forward-looking statements. The Company assumes no obligation to update any forward-looking statements as a result of new information, future events or developments, except as required by law.

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