Neihulizumab

Financing led by BVF Partners LP, with participation from new investors RA Capital Management, Cormorant Asset Management, Soleus Capital and existing investors aMoon Fund and Blackstone Multi-Asset Investing, among other new and existing investors Funds will be used to support ongoing and planned Phase 2a and 2b clinical trials of immune checkpoint enhancer, ALTB-268, in ulcerative colitis SAN FRANCISCO, May 21, 2024 (GLOBE NEWSWIRE) -- AltruBio Inc. (“AltruBio” or “the Company”), a clinical stage biotechnology company dedicated to the development of novel therapeutics for the treatment of immunological diseases with high unmet medical needs, today announced an oversubscribed Series B financing of up to $225 million. AltruBio plans to use the proceeds of the financing to advance the clinical development of the Company’s first-in-class, novel immune checkpoint enhancer (ICE) PSGL-1 agonist antibody, ALTB-268. The funds will be used to support ongoing and planned Phase 2 clinical trials in ulcerative colitis (UC), one of many immunological disorders where the mechanism has been clinically validated. The financing was led by BVF Partners LP with participation from new investors RA Capital Management, Cormorant Asset Management, and Soleus Capital, as well as existing investors aMoon Fund and Blackstone Multi-Asset Investing, with other new and existing investors joining the syndicate. The Company’s first-in-class, novel ICE agonist antibody, ALTB-268, is currently being studied in a Phase 2a exploratory biomarker study in patients with biologic refractory UC with an anticipated readout for its primary endpoint of clinical remission per modified Mayo score in 1H 2025. The company plans to initiate a global Phase 2b randomized, placebo-controlled clinical trial with a primary endpoint of clinical remission in both advanced therapy experienced and treatment naive patients with moderately to severely active UC. This study is anticipated to read out in 2H of 2026. "We are honored to welcome this esteemed new group of investors, whose participation complements the support of our existing world-class investor group. Their collective backing not only affirms the potential of our program and company but also our mission of developing durable biologic therapies for patients suffering from autoimmune diseases,” said Dr. Judy Chou, President and Chief Executive Officer of AltruBio. “With this substantial investment, we are one step closer to bringing our first-in-class, novel immune checkpoint enhancer, ALTB-268, through our ongoing Phase 2a exploratory biomarker study and initiate an additional Phase 2b study, while paving the way for potential indication expansion beyond ulcerative colitis. With our experienced team in place and this significant financing, we are poised to accelerate our efforts and deliver innovative treatments to patients in need." “Treatment options remain limited in many autoimmune conditions, including moderate to severe ulcerative colitis, and novel mechanisms are sorely needed,” commented Gorjan Hrustanovic, Ph.D., Managing Director at BVF Partners LP. “We are excited to support AltruBio and their commitment to developing a potential first-in-class medicine across multiple autoimmune indications, starting with UC.” “Our investment in AltruBio represents an exciting opportunity to contribute to the dynamic and rapidly evolving landscape of the inflammatory and immunological space. The heightened interest and substantial funding in this sector underscore the urgent need for innovative solutions to address the unmet medical needs of patients. We share a collective vision with AltruBio to advance first-in-class medicines, recognizing the potential to revolutionize patient care and drive impactful change within this field," said Jake Simson, Ph.D., Partner of RA Capital Management. About ALTB-268ALTB-268 is a tetravalent PSGL-1 agonist antibody that acts as an immune checkpoint enhancer (ICE) to preferentially downregulate chronically activated T-cells by inhibiting the T-cell effector function, promoting T-cell down regulation. ALTB-268 is designed to help restore the immune system to a state of balance without systemic suppression, and by treating immune diseases at their source. Its unique mechanism of action is the same as the bivalent intravenously administered ICE, ALTB-168, which has previously demonstrated promising Phase 2 results in ulcerative colitis, psoriasis, psoriatic arthritis, and SR/TR-aGvHD, including improved patient outcomes and clinically meaningful efficacy. ALTB-268 exhibited increased potency in preclinical studies and is formulated for subcutaneous dosing for patient-friendly administration. A Phase 1 study of ALTB-268 has demonstrated the safety and tolerability in healthy volunteers with no serious adverse events across all cohorts. A Phase 2a exploratory biomarker study for ALTB-268 in biologics-refractory ulcerative colitis patients is currently enrolling patients and a randomized Phase 2b study in ulcerative colitis is planned to be initiated later in 2024. Based on the relevance of T-cell modulation in many immunological diseases, ALTB-268 has broad expansion potential in different indications and hence has significant promise as a “pipeline-in-a-product.” About AltruBio Inc.AltruBio is a clinical-stage biotechnology company that specializes in developing novel therapies leveraging immune checkpoint agonism to enhance the function of natural pathways to downregulate an overactivated immune system. It is believed the mechanism of the immune checkpoint enhancers (ICEs) may hold the key to addressing the pressing medical needs of patients with autoimmune and inflammatory disorders. The Company’s research team was the first to discover the novel role PSGL-1 plays as an important immune checkpoint regulator and leveraged its ability to downregulate chronic effector T-cell function and promote down regulation. Robust clinical data validates proof of mechanism of the Company’s ICE therapy, ALTB-168, through enhancement of PSGL-1 function. ALTB-168 is designed to preferentially downregulate chronically activated late-stage T-cells in several diseases including ulcerative colitis, steroid refractory acute graft-versus-host disease (SR-aGvHD), psoriatic arthritis, and psoriasis, and was shown to be well tolerated with durable responses. Leveraging the same binding domain and novel mechanism demonstrated for ALTB-168, the Company is advancing a more potent tetravalent ICE, ALTB-268, making it suitable for subcutaneous and patient-friendly administration. ​Led by an expert team with successful track records in drug development and commercialization in immunological diseases, AltruBio’s mission is to bring safer, more effective, and durable biologic treatments to improve the lives of patients. MTS Securities, LLC acted as the exclusive placement agent in connection with the financing. Note on Forward-Looking StatementsStatements made in this news release that are not historical facts are forward-looking statements. These forward-looking statements include, but are not limited to, statements about the Series B financing, including those with respect to subsequent closings, the use of proceeds from the Series B financing, and the progress and timing of the Company’s clinical trials, including the timing and availability of data from such trials. Words such as expects, believes, plans, anticipates, intends, potential, design 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 achieve certain milestones and complete subsequent closings of the Series B financing, raise additional capital, and risks related to the Company's ability to initiate, and enroll patients in, planned clinical trials. The forward-looking statements included in this press release represent the Company’s views as of the date hereof. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date hereof. 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. Contacts AltruBio Inc: +1-415-655-6603 info@altrubio.com Media Contact:LifeSci CommunicationsLuke Shiplolshiplo@lifescicomms.com

AltruBio put ALTB-268 through a phase 1 study in healthy volunteers in 2023. AltruBio has roared back after another pivot in its twisty history, securing up to $225 million in series B funding to take an immune checkpoint enhancer through a midphase ulcerative colitis program. San Francisco-based AltruBio hit reset in 2021. Exiting oncology and prioritizing immunology left the biotech focused on a pipeline led by neihulizumab, an immune checkpoint agonist antibody designed to regulate T-cell homeostasis by targeting PSGL-1. The biotech terminated an ulcerative colitis trial in 2020, citing the pandemic, but was running an acute graft-versus-host disease study at the time of the reset.  Three years later, AltruBio has moved on from neihulizumab. The biotech remains focused on PSGL-1 but has switched horses, dropping neihulizumab in favor of ALTB-268. The new drug candidate has the same mechanism of action but is “subtly designed as a tetravalent molecule to achieve better efficacy.” According to AltruBio, the new lead prospect has shown improved potency in down-regulating chronic pathogenic T cells in preclinical and early human tests, raising hopes it can achieve equivalent efficacy to neihulizumab at lower doses. The biotech said the safety profiles are comparable.  AltruBio put ALTB-268 through a phase 1 study in healthy volunteers in 2023, leading to the initiation of a midphase study in patients with ulcerative colitis who are refractory to biologics. The biotech expects to report data on the primary clinical remission endpoint in the first half of 2025. Beyond that, AltruBio is planning a phase 2b trial that could report data in the second half of 2026. BVF Partners has signed up to support the program, leading a $225 million series B round that featured assists from new investors RA Capital Management, Cormorant Asset Management and Soleus Capital. Investors that supported AltruBio’s $63 million series A, including the lead aMoon Fund, returned for the latest financing.  AltruBio’s near-term focus is on ulcerative colitis, but the mechanism is potentially applicable to a range of other diseases. Neihulizumab showed promise in graft-versus-host disease, suggesting that indication is open to ALTB-268, and was studied in psoriatic arthritis and plaque psoriasis earlier in its R&D history. The breadth of the R&D program reflects the role activated T cells play in various inflammatory diseases. Binding PSGL-1 could down-regulate chronically activated T cells without altering the activity of resting and early-activated T cells. If ALTB-268 can achieve that balance, the molecule could take out the cells that drive multiple inflammatory diseases without diminishing the effectiveness of healthy immune cells.