Regeneron disclosed FDA contact about PCSK9 adverse events previously Regeneron (REGN) stated in its 10-K filing on February 13 after the market close that the company its partner Sanofi (SNY) have been advised by the FDA that it has become aware of neurocognitive adverse events in the PCSK9 inhibitor class. Similar wording was included in a regulatory filing made today by Sanofi and may be a factor in the volatility seen in shares of Regeneron this afternoon. Shares of Regeneron are off their earlier lows but remain down about 7.8% near $312 per share. Shares of Aegerion (AEGR) spiked as Regeneron shares sold off, but are off their earlier highs. Aegerion remains up about 4.5% near $52.50 in afternoon trading.