Karyopharm announced the partial hold on Friday.
The firm explained the US Food and Drug Administration (FDA) had asked it not to start new trials of the injectable formulation following a review of three mild-to-moderate thrombotic events in patients receiving the highest doses and highest concentrations of SCY-078 in a Phase I study.
A spokeswoman told us "The hold applies only to the IV formulation of SCY-078. Ongoing and future trials using the oral formulation of SCY-078 are unaffected by this regulatory action.”
She added that: "Even though the rates of thrombotic events due to I.V. catheters reported in the literature are comparable to those that turned up in Scynexis’ phase I study, volunteers in the clinical trial were getting SCY-078 at the highest doses and in the highest concentrations.
“We believe the issue may be related to the action of the catheter itself; however, we cannot rule out possible contribution by the drug. Given such, the next steps would be to minimize the possibility of that happening.”
She also said that: "We do not anticipate having to change the formulation as we believe we have identified a tolerable dose that achieves an appropriate target exposure in humans, suitable for use in subsequent studies."
Karyopharm also revealed it has submitted an amended investigator brochure that includes a full list of serious adverse events (SAEs) associated with selinexor (KPT-330), which was requested by the FDA.
The FDA has 30 days to review the revisions according to Karyopharm, which predicted the partial hold will not impact previously disclosed timelines for ongoing clinical trials.