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# FDA Lifts Clinical Holds on Seattle Genetics Leukemia Drug
- URL: https://www.fdaweb.com/fda-lifts-clinical-holds-on-seattle-genetics-leukemia-drug/
- Published: 2017-03-06T12:00:00.000Z
- Updated: 2026-09-14T22:10:05.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5138135

FDA has lifted clinical holds against several Seattle Genetics Phase 1 trials of vadastuximab talirine (SGN-CD33A; 33A) in acute myeloid leukemia. “The clinical hold on our early-stage vadastuximab talirine clinical trials has been resolved through a comprehensive analysis of the clinical data from over 300 patients treated to date, evaluation by an independent committee of clinical experts, collaborative interactions with the FDA, and protocol amendments designed to further enhance patient safety,” the company says.

The 12/2016 clinical holds were initiated to evaluate the potential risk of hepatotoxicity in patients who were treated with SGN-CD33A and received allogeneic stem cell transplant either before or after treatment. Six patients had been identified with hepatotoxicity, including several cases of veno-occlusive disease, with four fatal events.

  
Vadastuximab talirine is described by the company as a novel investigational ADC targeted to CD33 utilizing Seattle Genetics’ proprietary ADC technology. The CD33-engineered cysteine antibody is “stably linked to a highly potent DNA binding agent called a pyrrolobenzodiazepine (PBD) dimer via site-specific conjugation technology (EC-mAb),” it says. “PBD dimers are significantly more potent than systemic chemotherapeutic drugs and the EC-mAb technology allows uniform drug-loading onto an ADC. The ADC is designed to be stable in the bloodstream and to release its potent cell-killing PBD agent upon internalization into CD33-expressing cells.”