Frenlosirsen sodium

Frenlosirsen sodium (ION-935918 sodium; ION251 sodium) is an antisense oligonucleotide and also an IRF4 inhibitor. Frenlosirsen sodium inhibits the survival of malignant plasma cells, reduces the burden of myeloma progenitor cells and prevents disease recurrence. Frenlosirsen sodium is applicable to myeloma-related research ^{[1] [2]}.

In Vivo, Frenlosirsen (ION251) sodium is an antisense oligonucleotide targeting IRF4. It inhibits the survival of malignant plasma cells, reduces the burden of myeloma progenitor cells, disrupts cell cycle progression to block myeloma regeneration, and does not damage normal hematopoietic stem cells^[1][2]. Frenlosirsen (28-day dosing cycle, intravenous infusion, maximum dose of 660 mg) sodium shows no dose-limiting toxicity and only mild drug-related adverse events in a Phase 1a clinical study of relapsed/refractory multiple myeloma^[2].

References:
[1]. Hartman JD, et al. Optimal conditions for quantification of IRF4 mRNA and protein as a correlative biomarker in clinical cancer studies. Journal of translational medicine. 2026 Mar 16;24(1):575.
[2]. Tong A A, et al. Abstract CT146: Safety, tolerability and molecular correlates of the IRF4-targeted antisense oligonucleotide frenlosirsen in patients with relapsed/refractory multiple myeloma: A phase 1a dose escalation trial. Cancer Research, 2025, 85(8_Supplement_2): CT146.