Exhibit 99.1 Targeting Disease at the Nuclear Pore Karyopharm Reports First Quarter 2024 Financial Results and Highlights Recent Company Progress – Announces Significant Refinancing Transactions and Amends Royalty Agreement with HealthCare Royalty Extending Vast Majority of Its Debt Maturities into 2028 and 2029, Well Beyond Expected Data Readouts and Potential Approvals from the Company’s Three Phase 3 Trials, Strengthening the Company for its Next Stage of Growth – – Achieves First Quarter 2024 Total Reve ...