Exhibit 99.1 Y-mAbs Reports First Quarter 2024 Financial Results and Recent Corporate Developments ● Reported U.S. DANYELZA® net product revenues of $18.6 million for the first quarter of 2024, representing a YoY increase of 11% ● Reported Worldwide DANYELZA net product revenues of $19.4 million for the first quarter of 2024, representing a 4% YoY decrease due to international volumes ● Cash and cash equivalents of $75.7 million as of March 31, 2024, and cash burn of only $2.9 million for the quarter ended ...