Ultragenyx Pharmaceutical's (NASDAQ:RARE) Phase II study of UX007 (triheptanoin) in glucose transporter type-1 deficiency syndrome (Glut1 DS) with the seizure phenotype (NCT01993186) has had five patients out of 32 enrolled drop out, an investigator said. There has also been one serious adverse event in a patient with a local infection related to percutaneous gastrostomy, he said.
The investigator said all three of his patients dropped out due to gastrointestinal (GI) side effects, and a further two at other sites for unknown reasons. His patient dropouts happened once the study's dose doubled at weeks 4/5, he said.
An Ultragenyx spokesperson did not comment on reports of patients dropping out, GI effects or other safety events. She said data will be announced in 2H16.
Experts debated the role of GI tolerability on the ultimate trial impact, with the investigator doubting ultimate trial success but another two doctors, including an investigator, indicating they had no GI concerns. Safety is the study's secondary endpoint.
Overall, experts noted they still expected a positive efficacy profile, based on strong seizure reduction signals although the measures may underestimate seizure frequency. A second investigator noted successful changes in functional measures but their clinical utility was doubted by another expert.