Shares of Ionis Pharmaceuticals (IONS) and its majority-owned spinout Akcea Therapeutics (AKCA) are sliding after the Food and Drug Administration posted its briefing document ahead of Thursday's meeting to discuss the latter's volanesorsen. The internal review reflected deep concerns about the safety of the drug.

INTERNAL REVIEW: An FDA panel posted its briefing document ahead of Thursday's meeting to discuss Akcea's volanesorsen. The document reads, "Despite the magnitude of the effect observed on TG, the volanesorsen review team remains uncertain whether the benefits of volanesorsen outweighs its risks, considering safety concerns with this product. Although the reviews highlight several safety/tolerability issues, the primary focus for both the applicant and the reviewers has been the risk of thrombocytopenia and resulting potential for serious bleeding." The document adds, "After the NDA review was well-underway, the applicant unexpectedly submitted an amendment that proposed a new dosing and platelet monitoring strategy for labeling that had not been implemented in any of the clinical trials... Regarding platelet monitoring, the review team (including the hematology consultant) questions the feasibility and effectiveness of a monitoring scheme of this intensity for a lifelong therapy. At present, we have no evidence that the risk of severe thrombocytopenia diminishes with time."

EVERCORE MOVING TO THE SIDELINES: After reviewing the FDA's briefing documents, Evercore ISI analyst Josh Schimmer noted incremental concerns about volanesorsen and downgraded Ionis Pharmaceuticals to In Line from Outperform, while lowering his price target on the shares to $46 from $55. The analyst argued that the FDA dismantled the company's claims that volanesorsen leads to a benefit in pancreatitis, which dampens clinical utility relative to the obvious concerns about thrombocytopenia. While Schimmer had not ascribed "MUCH" value to volanesorsen, he is stripping it out of his model for now. Even if volanesorsen is approved, these documents indicate a need for meaningful commercial spend relative to what will likely be minimal product adoption, he contended. Additionally, the analyst pointed out that Alnylam Pharmaceuticals (ALNY) indicated that it is advancing its RNAi platform from central nervous system, or CNS, therapy, which now introduces a relevant new competitor to the antisense-field.

PRICE ACTION: In later morning trading, shares of Ionis have dropped almost 8% to $40.96, while Akcea's stock has fallen 14% to $18.68.