Alnylam shares tumble nearly 30% after cutting revenue outlook for key amyloidosis drugs

Alnylam Pharmaceuticals saw its market value drop about 30%, roughly $12 billion, after it lowered its revenue forecast for its leading amyloidosis treatments.

The company had previously expected the two drugs, Amvuttra and Onpattro, to generate between $4.4 billion and $4.7 billion, but the new guidance narrows that range to $4.2-$4.5 billion, citing a normalization of early demand for Amvuttra.

The revision comes as competition intensifies in the transthyretin cardiomyopathy space, with rivals such as Pfizer’s Vyndamax and BridgeBio’s Attruby already on the market and other candidates under development.

Investors are also watching a recent study setback for Alnylam’s experimental drug eplontersen, which raised questions about its effectiveness in patients already receiving other therapies.