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Arrowhead and Ionis Clash Over FCS Drug Patents

9/12/2025

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Summary

Story summary

Arrowhead Pharmaceuticals and Ionis Pharmaceuticals are in litigation over familial chylomicronemia syndrome (FCS) therapies.
Ionis alleges Arrowhead infringed its messenger RNA patent with plozasiran.
Arrowhead counters that its drug is based on its own research and does not infringe Ionis' patent.
The FDA approved Ionis' drug Tryngolza in December, a key advancement for FCS treatment.
Ionis seeks damages in California, while Arrowhead aims to invalidate Ionis' patent in Delaware.

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Story summary

Arrowhead Pharmaceuticals and Ionis Pharmaceuticals are in litigation over familial chylomicronemia syndrome (FCS) therapies.
Ionis alleges Arrowhead infringed its messenger RNA patent with plozasiran.
Arrowhead counters that its drug is based on its own research and does not infringe Ionis' patent.
The FDA approved Ionis' drug Tryngolza in December, a key advancement for FCS treatment.
Ionis seeks damages in California, while Arrowhead aims to invalidate Ionis' patent in Delaware.