Clinical Trial Info

Safety and Tolerability of an Antibody Against Yellow Fever Virus (TY014) in Humans

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This is a Phase 1, first-in-human TY014, YFV monoclonal antibody (mAb), study to be conducted in two (2) arms:

  • Safety Arm (1A): Healthy adult volunteers
  • Efficacy Arm (1B): Healthy adult volunteers challenged with YF-17D Vaccine Strain 24 hours prior to TY014 dosing

TY014 will be administered once through single IV infusion over 30 minutes. Total duration of study participation is estimated at approximately 114 days from the date of screening.

The main objectives of this study are: (a) evaluate the safety of TY014 in healthy adult volunteers, and (b) evaluate the safety of TY014 in YF-17D Vaccine Strain-challenged healthy adult volunteers. Percentage aviremia of YF-17D Vaccine Strain-challenged subjects within 48 hours after IV infusion of TY014 will also be assessed.


The New England Journal of Medicine published the results of this clinical trial on July 30, 2020.

A total of 27 healthy participants were enrolled in phase 1a, and 10 participants in phase 1b. During phase 1a, TY014 dose escalation to a maximum of 20 mg per kilogram of body weight occurred in 22 participants. During phases 1a and 1b, adverse events within 1 hour after infusion occurred in 1 of 27 participants who received TY014 and in none of the 10 participants who received placebo. At least one adverse event occurred during the trial in 22 participants who received TY014 and in 8 who received placebo. The mean half-life of TY014 was approximately 12.8 days. At 48 hours after the infusion, none of the 5 participants who received the starting dose of TY014 of 2 mg per kilogram had detectable YF17D-204 viremia; these participants remained aviremic throughout the trial. Viremia was observed at 48 hours after the infusion in 2 of 5 participants who received placebo and at 72 hours in 2 more placebo recipients. Symptoms associated with yellow fever vaccine were less frequent in the TY014 group than in the placebo group.


This phase 1 trial of TY014 did not identify worrisome safety signals and suggested potential clinical benefit, which requires further assessment in a phase 2 trial.