The phase 3 CASCADE trial evaluating vadastuximab talirine (SGN-CD33A) plus chemotherapy among patients with acute myeloid leukemia (AML) was discontinued by Seattle Genetics Inc due to a higher rate of deaths compared with chemotherapy alone.

Vadastuximab talirine is an antibody-drug conjugate targeted to CD33, which is expressed on most AML and myelodysplastic syndrome (MDS) blast cells.

The CASCADE trial ( Identifier: NCT02785900) is a randomized, double-blind study that treated older patients with AML with azacitidine or decitabine compared with plus vadastuximab talirine plus or placebo.

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Seattle Genetics decided to halt the study following review of unblinded data on June 16, 2017 by the Independent Data Monitoring committee.

The data showed a higher rate of death, including fatal infections, in the vadastuximab talirine arm compared with the chemotherapy-only arm. Hepatotoxicity, however, was not associated with the deaths.

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Patient enrollment and treatment in all vadastuximab talirine clinical trials, including a phase 1b trial in myelodysplastic syndrome, were suspended.

The data will be reviewed in consult with the US Food and Drug Administration to determine next steps.


  1. Seattle genetics discontinues phase 3 CASCADE trial of vadastuximab talirine (SGN-CD33A) in frontline acute myeloid leukemia [news release]. Bothell, WA: Seattle Genetics; June 19, 2017. Accessed June 19, 2017.