Rallybio Completes $145 Million Series B Financing and Unveils Lead Candidate for Development

Rare Daily Staff

Rallybio completed a $145 million series B financing to advance its pipeline of therapies targeting rare diseases and announced its lead product candidate for development—fetal and neonatal alloimmune thrombocytopenia, a potentially life-threatening rare disease that impacts fetuses and newborns.

Pivotal bioVenture Partners led the financing and included new investors Viking Global Investors, TPG’s The Rise Fund, F-Prime Capital, funds managed by Tekla Capital Management, Solasta Ventures, Fairview Capital, and Mitsui & Co. Global Investment. Existing investors 5AM Ventures, Canaan Partners, New Leaf Venture Partners and Connecticut Innovations also participated in the financing.

When the company was launched in January 2018, co-founders and former Alexion Pharmaceutical executives Martin Mackay, Stephen Uden, and Jeffrey Fryer said they would take an agnostic approach to selecting which rare diseases they would target. Since then, it has built a portfolio of experimental candidates to address rare diseases in the areas of hematology, immuno-inflammation, and metabolism.

“The Rallybio team is highly motivated to bring our innovative product candidates to patients suffering from devastating rare disorders,” said Mackay, chairman and CEO of Rallybio.

Proceeds from the financing will be used to advance Rallybio’s pipeline, including its lead program, RLYB211, which is in development for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT), a potentially life-threatening rare disease that can cause uncontrolled bleeding in fetuses and newborns.

FNAIT is a disorder that can occur during pregnancy and is caused by an incompatibility between mother and fetus of a specific human platelet antigen (HPA), most commonly HPA-1. This incompatibility can cause a pregnant woman to develop antibodies that attack the platelets of her fetus. The destruction of platelets in the fetus can result in severe thrombocytopenia in the baby, potentially leading to intracranial hemorrhage, the consequences of which can be devastating, and include miscarriage of the fetus, loss of the newborn, or severe lifelong neurological disability in those babies who survive.

RLYB211 is a plasma-derived hyperimmune globulin designed to prevent FNAIT through a mechanism known as antibody-mediated immune suppression. There is currently no approved therapy for the prevention or treatment of FNAIT. Rallybio plans to initiate a phase 1/2 clinical study of RLYB211 in the second half of 2020.

RLYB211 has received Orphan Drug designation from both the U.S. Food and Drug Administration and from the European Medicines Agency, and a Rare Pediatric Disease designation by the FDA.

Proceeds from the financing will also be used to advance a pipeline that includes preclinical candidates to address a rare hematologic disease, and rare immuno-inflammatory diseases, plus a discovery-stage program targeting a rare metabolic disease as part of a joint venture with Exscentia. Proceeds will also be used to further expand its portfolio.

Photo: Rallybio co-founders Jeffrey Fryer, Martin Mackay, and Stephen Uden