Alnylam makes a bull case for PhIII-ready porphyria drug, but shares sink anyway

Alnylam today offered some details on the data it has gathered from a small, early-stage study of givosiran for rare cases of porphyrias. The data provide some insights on the therapy’s positive impact in preventing fresh attacks, but the biotech’s shares $ALNY were down 3.6% in afternoon trading as analysts looked through the numbers and pondered the durability of a recent run-up in the stock price.

There were only nine patients in the three drug cohorts, but researchers say they were able to track a 63% drop in the number of attacks compared to the run-in period of the study.

Jeff Miller, Alnylam

The drug is designed to switch off ALAS1 mRNA and slash levels of aminolevulinic acid (ALA) and porphobilinogen (PBG) tied to the attacks and chronic symptoms of the disease. The worst cases are treated with injected hemin, which has its own known side effects. There are no drugs for this condition.

Alnylam confirmed that the one death tracked in the study was in a drug arm, noting:

Excluding porphyria attacks, three patients had four SAEs; none were assessed as related to study drug. As previously reported, one death occurred in a patient in cohort 3 in the givosiran arm due to hemorrhagic pancreatitis complicated by a pulmonary embolism and following a recent hospitalization for bacteremia; the death was considered to be unlikely related to study drug by the investigator and the study’s Safety Review Committee.

Program manager Jeff Miller also reconfirmed plans to launch a pivotal Phase III study later this year. Givosiran’s importance to Alnylam grew significantly after the biotech announced in March that it had to scrap its number two drug in the pipeline due to patient deaths. RNAi therapies have had a mixed record on the safety side.


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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
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Atlas Venture Cambridge, MA

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