The company discontinued development last month of its most mature asset, RLYB212, following disappointing mid-stage pharmacokinetic findings in a rare bleeding disorder.
Rallybio is laying off nine employees, about 40% of its total headcount, as it reels from the loss of its lead asset, the biotech announced in its first-quarter earnings report on Thursday.
The terminations will be “substantially complete” by the end of the second quarter, according to the press release. Rallybio expects to absorb roughly $1.7 million in one-time costs, primarily linked to severance and benefit payments. This sum, however, still excludes share-based compensations. At the end of Q1, the biotech had $54.5 million on hand, which it expects can keep it afloat into the first half of 2027.
Last month, Rallybio was forced to drop its former lead molecule RLYB212 following its disappointing pharmacokinetic performance in a Phase II trial. The candidate, an investigational monoclonal antibody, was being trialed for a rare bleeding disorder called fetal and neonatal alloimmune thrombocytopenia, where a mother’s immune system attacks the fetus.
In the mid-stage study, RLYB212 failed to reach its target concentration, or even the minimum level required for efficacy.
“The risk/benefit no longer supports continued dosing, and we will discontinue RLYB212 development,” Rallybio CEO Stephen Uden said in a statement at the time.
Now without its most advanced clinical asset, Rallybio has fallen back on its earlier-stage molecules. The biotech’s new lead candidate is RLYB116, a C5 blocker currently in Phase I development for diseases driven by a dysregulated complement system. According to its press announcement on Thursday, Rallybio is “on track” to start dosing patients in the confirmatory pharmacokinetic/pharmacodynamic study, with results expected in the back half of the year.
“We are well-positioned to maximize RLYB116’s transformative potential across multiple billion-dollar market opportunities,” Uden said in a statement on Thursday.
Aside from RLYB116, Rallybio is also working on REV102, an investigational small molecule inhibitor of the ENPP1 protein, which is involved in breaking down adenosine triphosphate, the primary molecular currency of energy in cells. REV102 is currently in IND-enabling studies for hypophosphatasia, a rare metabolic disorder characterized by impaired bone development.
Rallybio is developing REV102 in collaboration with Recursion Pharmaceuticals. The partners expect to push the candidate into the clinic in the second half of 2026.
Rallybio has two other preclinical programs: the matriptase-2 inhibitor RLYB332, for iron overload and severe anemia, and the C5 blocker RLYB114 for eye conditions related to complement dysregulation. The biotech is also working on drug discovery for a program for an undisclosed metabolic disorder.
