2 Reasons Seattle Genetics' Clinical Holds Were A Surprise

On Tuesday, Seattle Genetics, Inc. SGEN announced that the FDA had imposed several clinical holds upon the Phase I trials for SGN-CD33A due to cases of hepatic veno-occlusive disease.

Credit Suisse’s Kennen MacKay maintains a Neutral rating on the company, while lowering the price target from $70 to $60.

Surprising Announcement

Expressing surprise at this development, the analyst explained that SGN-CD33A had been designed to address the pitfalls of the antibody-drug conjugate linker technology that had been observed with the drug candidate’s predecessor, Mylotarg.

In addition, MacKay noted that prior to this announcement, there had been no HVOD concerns observed in the early stages of testing for SGN-CD33A.

The analyst also pointed out that “while the incidence of Mylotarg’s HVOD had been commonly attributed to pre-mature cleavage of the cytotoxic payload, concern continues to exist surrounding potential CD33 target-mediated hepatotoxicity.

The PoS estimate in frontline older/unfit AML had been lowered from 70 percent to 30 percent, and from 30 percent to 15 percent for frontline younger/fit AML.