Chemistry: Generation 2.5
Frenlosirsen, formerly known as ION251 and IONIS-IRF4-2.5Rx, is an investigational antisense medicine.
Interferon Regulatory Factor 4 (IRF4) is a transcription factor expressed in lymphocytes, where it directs terminal differentiation of B-cells to plasma cells and also has roles in T cell functions such as T cell exhaustion. IRF4 has emerged as a key regulator of multiple genes controlling the survival of multiple myeloma (MM) tumor cells as well as other B-cell malignancies. IRF4 is overexpressed in MM as a result of several mechanisms including activating mutations in the DNA binding domain and translocations. Even limited depletion of IRF4 leads to rapid cell death of MM tumor cells, and as such MM is considered to be “addicted” to IRF4. Taken together, selective inhibition of IRF4 with a therapeutic antisense oligonucleotides (ASO) is an attractive strategy for the treatment of MM with the potential for potent MM cell kill with limited effects on normal cells.
About Multiple Myeloma
Multiple Myeloma (MM) is an incurable cancer characterized by uncontrolled proliferation of bone marrow plasma cells. Despite their initial responses to current therapies, almost all MM patients eventually relapse with a median overall survival time of 13 months following relapse, presenting a strong need for new treatments. Interferon Regulatory Factor 4 (IRF4) is a transcription factor involved in immune cell development and is essential for plasma cell differentiation. IRF4 has emerged as a key regulator of multiple genes controlling the survival of MM and other B-cell malignancy such as c-Myc and is aberrantly expressed in MM as a result of activating mutations and translocations.