Rare Daily Staff

Rallybio, which develops antibodies targeting rare diseases, raised $80.6 million in an initial public offering of 6.2 million shares of common stock at $13.00 per share, the lower end of its proposed range of $13 to $15. 

The shares will trade on the Nasdaq Global Market under the ticker symbol “RLYB.” In addition, Rallybio has granted the underwriters a 30-day option to purchase up to an additional 930,000 shares of common stock at the initial public offering price, less underwriting discounts and commissions.

Rallybio is the 19th  rare disease drug developer to complete an IPO so far this year, with these companies raising a collective $3.6 billion in new capital to advance their programs.

Since its launch in early 2018 by co-founders and former Alexion Pharmaceutical executives Martin Mackay, Stephen Uden, and Jeffrey Fryer, Rallybio has built a portfolio of experimental candidates to address rare diseases in the areas of hematology, immuno-inflammation, and metabolism.

The company’s lead program, RLYB211, 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. The company is currently testing it in a phase 1/2 trial for the treatment of FNAIT and expects to report data from the trial in the second half of 2021. The company also has four preclinical programs, one of which, RLBY212, is also being developed for the treatment of FNAIT, and two of which are being developed for the treatment of complement dysregulation diseases.

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.

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