Rallybio Announces Promising RLYB212 and RLYB332 Preclinical Data at the 66th American Society of Hematology Annual Meeting

Rallybio Corporation (Nasdaq: RLYB), a clinical-stage biotechnology company translating scientific advances into transformative therapies for patients with devastating rare diseases, today announced the presentation of two posters highlighting promising preclinical data for pipeline candidates RLYB212 and RLYB332 at the 66^th American Society of Hematology (ASH) Annual Meeting and Exposition, taking place December 7–10, 2024 in San Diego, California.

“With our Phase 2 trial underway evaluating RLYB212 in pregnant women at higher risk of maternal alloimmunization and FNAIT, we are pleased that our collaborators at Versiti continue to add to the preclinical data showing RLYB212 has the potential to be a safe and effective preventative therapeutic using innovative nonclinical models,” said Stephen Uden, M.D., Chief Executive Officer of Rallybio. “Additionally, we are delighted to share, for the first time, preclinical data demonstrating the potential for RLYB332, our long-acting anti-matriptase-2 antibody, to be a best-in-class therapeutic for patients with diseases of iron overload.”

In a poster titled “Prophylactic Administration of HPA-1a–Specific Antibody RLYB212 Safely Prevents Fetal/Neonatal Alloimmune Thrombocytopenia Due to HPA-1a Incompatibility in Pregnant Mice,” preclinical data was presented demonstrating that prophylactic administration of RLYB212 to pregnant mice at doses of 1.01 or 5.05 µg/kg prevented maternal alloimmunization. Further, pups born to RLYB212-treated, but not untreated, pregnant mice had normal platelet counts, demonstrating the ability of RLYB212 to prevent fetal and neonatal alloimmune thrombocytopenia (FNAIT). Data also showed that administration of RLYB212 did not cause thrombocytopenia in pups, supporting its safety as a prophylactic treatment.

In a poster titled “Long-Acting Anti-Matriptase-2 Antibody as a Potentially Best-in-Class Therapy for Iron Overload Diseases,” preclinical data was presented demonstrating that single intravenous injections of RLYB332 to humanized FcRn mice had rapid and sustained effects on pharmacodynamic (PD) parameters, including serum iron, unsaturated iron binding capacity (UIBC), and transferrin saturation (TSAT), and these effects were greater than those produced by comparator molecules. Additionally, treatment with RLYB332 was generally well-tolerated. These findings support RLYB332 as a potentially best-in-class therapeutic for the treatment of diseases of iron overload.

Poster presentation details:

Title: Prophylactic Administration of HPA-1a–Specific Antibody RLYB212 Safely Prevents Fetal/Neonatal Alloimmune Thrombocytopenia in Pregnant Mice

Publication Number: 1185

Session Name: 311. Disorders of Platelet Number or Function: Clinical and Epidemiological: Poster I

Session Date: Saturday, December 7, 2024

Presentation Time: 5:30 p.m. - 7:30 p.m. PT

Title: Long-Acting Anti-Matriptase-2 Antibody as a Potentially Best-in-Class Therapy for Iron Overload Diseases

Publication Number: 3854

Session Name: 102. Iron Homeostasis and Biology: Poster III

Session Date: Monday, December 9, 2024

Presentation Time: 6:00 p.m. - 8:00 p.m. PT

About Rallybio

Rallybio (NASDAQ: RLYB) is a clinical-stage biotechnology company with a mission to develop and commercialize life-transforming therapies for patients with severe and rare diseases. Rallybio has built a broad pipeline of promising product candidates aimed at addressing diseases with unmet medical needs in areas of maternal fetal health, complement dysregulation, hematology, and metabolic disorders. The Company has two clinical stage programs: RLYB212, an anti-HPA-1a antibody for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT) and RLYB116, a C5 inhibitor with the potential to treat several diseases of complement dysregulation, as well as additional programs in preclinical development. Rallybio is headquartered in New Haven, Connecticut. For more information, please visit www.rallybio.com and follow us on LinkedIn and Twitter.

Forward-Looking Statements

This press release contains forward-looking statements that are based on our management’s beliefs and assumptions and currently available information. All statements, other than statements of historical facts contained in this press release are forward-looking statements. In some cases, forward-looking statements can be identified by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, statements concerning our expectations regarding future favorable clinical results based on RLYB212 and RLYB332 preclinical data, including our expectations regarding efficacy, safety, dosing, and administration, whether a monoclonal antibody inhibitor of matriptase-2 will be an effective treatment of diseases of iron overload, and the potential success of RLYB212 and RLYB332 for the diseases that we expect to treat. The forward-looking statements in this press release are only predictions and are based largely on management’s current expectations and projections about future events and financial trends that management believes may affect Rallybio’s business, financial condition and results of operations. These forward-looking statements speak only as of the date of this press release and are subject to a number of known and unknown risks, uncertainties and assumptions, including, but not limited to, our ability to successfully initiate and conduct our planned clinical trials, including the FNAIT natural history study, and a Phase 2 clinical trial for RLYB212, and complete such clinical trials and obtain results on our expected timelines, or at all, whether our cash resources will be sufficient to fund our operating expenses and capital expenditure requirements and whether we will be successful raising additional capital, our ability to enter into strategic partnerships or other arrangements, competition from other biotechnology and pharmaceutical companies, and those risks and uncertainties described in Rallybio’s filings with the U.S. Securities and Exchange Commission (SEC), including Rallybio’s Quarterly Report on Form 10-Q for the period ended September 30, 2024, and subsequent filings with the SEC. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual future results, levels of activity, performance and events and circumstances could differ materially from those projected in the forward-looking statements. Except as required by applicable law, we are not obligated to publicly update or revise any forward-looking statements contained in this press release, whether as a result of any new information, future events, changed circumstances or otherwise.

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