Rallybio shares tumble 36% after RLYB212 program halt

Investing.com -- Shares of Rallybio Corp (NASDAQ:RLYB) plummeted 36.5% following the company's announcement to discontinue its RLYB212 program, which was in development for the prevention of fetal and neonatal alloimmune thrombocytopenia (FNAIT). The decision came after Phase 2 clinical trial pharmacokinetic data revealed that the drug could not achieve the necessary target concentrations for efficacy.

The clinical-stage biotechnology firm, specializing in therapies for rare diseases, disclosed that the RLYB212 dose regimen failed to reach predicted target concentrations, based on results from the Phase 2 trial. This outcome, combined with the lack of empirical data to support dose adjustments, led to the conclusion that the risk/benefit profile no longer justified continuing the program.

Rallybio's CEO, Stephen Uden, expressed disappointment over the trial results, acknowledging the deviation from the predicted concentration range and confirming the discontinuation of RLYB212's development. Despite this setback, Uden emphasized the company's commitment to developing transformative therapies for patients with rare diseases. Rallybio is shifting focus to advance RLYB116, a C5 inhibitor, and its preclinical programs, including REV102 for hypophosphatasia and RLYB332 for iron overload diseases.

The discontinued RLYB212 trial aimed to assess the drug's pharmacokinetics and safety in pregnant women at risk for FNAIT. However, the sentinel participant's second-trimester results showed that the drug did not meet the minimum efficacy concentration levels, prompting the company to halt further enrollment and screening.

Looking ahead, Rallybio is preparing to initiate dosing in the RLYB116 confirmatory clinical pharmacokinetic/pharmacodynamic study in the second quarter of 2025. Data from this study are expected in the latter half of the same year. The company also plans to progress with its other preclinical programs, with IND-enabling studies for REV102 already underway and preclinical data for RLYB332 showing promising results.

Investors reacted to the news by selling off shares, reflecting concerns over the discontinued program's impact on Rallybio's pipeline and future prospects.

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