Pharming (PHAR) said Sunday the US Food and Drug Administration issued a complete response letter to its supplemental marketing application for Joenja, intended for children aged 4 to 11 with activated phosphoinositide 3-kinase delta syndrome, a rare immune disorder.

The drugmaker said the health agency raised concerns about potential underexposure in lower-weight children and requested additional pediatric pharmacokinetic data to confirm proper dosing.

The agency also flagged an issue with one analytical method used in production batch testing and requested further clarification, it added.

Pharming said the issues raised by the agency can be addressed and plans to work closely with the FDA, including requesting a Type A meeting, to determine next steps for resubmission.