Ionis Pharmaceuticals is an American biotechnology company headquartered in Carlsbad, California, founded in 1989 as ISIS Pharmaceuticals. The company is a pioneer in antisense oligonucleotide (ASO) therapeutics and has developed a leading platform for RNA-targeted drug discovery[@bennett2019]. Ionis is best known for its strategic partnership with Biogen, which has led to multiple approved ASO therapies for neurological diseases including Tofersen (Qalsody) for SOD1-ALS and multiple programs in development for Alzheimer's and [Parkinson's disease](/diseases/parkinsons-disease)[@biogen2024].
Founded by Dr. Stanley Crooke, Ionis (originally ISIS Pharmaceuticals) began as a pioneer in antisense technology, which uses short synthetic DNA sequences to bind to specific messenger RNA molecules and prevent them from being translated into proteins. The company's early work focused on genetic disorders, but its partnership with Biogen beginning in the early 2000s shifted focus toward neurological diseases[@crooke2021].
The company's most significant achievement came with the development of Tofersen (brand name Qalsody), an ASO therapy for SOD1-mutated amyotrophic lateral sclerosis (ALS). In 2023, the FDA granted accelerated approval for Tofersen, making it the first ASO therapy to receive regulatory approval for a neurological disease outside of the spinal muscular atrophy (SMA) space[@miller2022].
Ionis Pharmaceuticals is an American biotechnology company headquartered in Carlsbad, California, founded in 1989 as ISIS Pharmaceuticals. The company is a pioneer in antisense oligonucleotide (ASO) therapeutics and has developed a leading platform for RNA-targeted drug discovery[@bennett2019]. Ionis is best known for its strategic partnership with Biogen, which has led to multiple approved ASO therapies for neurological diseases including Tofersen (Qalsody) for SOD1-ALS and multiple programs in development for Alzheimer's and [Parkinson's disease](/diseases/parkinsons-disease)[@biogen2024].
Founded by Dr. Stanley Crooke, Ionis (originally ISIS Pharmaceuticals) began as a pioneer in antisense technology, which uses short synthetic DNA sequences to bind to specific messenger RNA molecules and prevent them from being translated into proteins. The company's early work focused on genetic disorders, but its partnership with Biogen beginning in the early 2000s shifted focus toward neurological diseases[@crooke2021].
The company's most significant achievement came with the development of Tofersen (brand name Qalsody), an ASO therapy for SOD1-mutated amyotrophic lateral sclerosis (ALS). In 2023, the FDA granted accelerated approval for Tofersen, making it the first ASO therapy to receive regulatory approval for a neurological disease outside of the spinal muscular atrophy (SMA) space[@miller2022].
Ionis maintains a robust neuroscience pipeline through its partnership with Biogen, with multiple programs in various stages of clinical development for [Alzheimer's disease](/diseases/alzheimers-disease), Parkinson's disease, and other neurodegenerative conditions.
| Drug Name | Target | Mechanism | Indication | Phase | Status |
|-----------|--------|-----------|------------|-------|--------|
| Tofersen (Qalsody) | SOD1 | ASO - RNase H-mediated mRNA degradation | SOD1-ALS | Approved (2023) | Marketed |
| BIIB080 (Tau ASO) | MAPT | ASO - tau mRNA reduction | Alzheimer's Disease | Phase 2 | Active |
| BIIB132 ([LRRK2](/entities/lrrk2) ASO) | LRRK2 | ASO - LRRK2 mRNA reduction | Parkinson's Disease | Phase 1 | Active |
| IONIS-MAPTRx | MAPT | ASO - tau protein reduction | Alzheimer's Disease | Phase 1/2 | Completed |
| IONIS-GBA2 | [GBA](/entities/gba) | ASO - GCase modulation | Parkinson's Disease (GBA carriers) | Preclinical | Discovery |
| IONIS-[C9orf72](/entities/c9orf72) | C9orf72 | ASO - repeat expansion targeting | ALS/FTD (C9orf72) | Phase 1 | Active |
| IONIS-HTT | HTT | ASO - [huntingtin](/proteins/huntingtin) reduction | Huntington's Disease | Phase 1/2 | Active |
| IONIS-SOD1 | SOD1 | ASO - SOD1 reduction | ALS | Phase 3 | Completed |
| BIIB105 | ATXN2 | ASO - ataxin-2 reduction | ALS | Phase 1 | Active |
| IONIS-P2X7 | P2X7R | ASO - P2X7 receptor reduction | Neuroinflammation | Phase 1 | Active |
Mutations in the [LRRK2](/genes/lrrk2) gene are the most common genetic cause of [Parkinson's disease](/diseases/parkinsons-disease). Ionis, in partnership with Biogen, is developing BIIB132, an ASO therapeutic designed to reduce LRRK2 protein expression in patients with pathogenic LRRK2 mutations[@lang2019].
BIIB132 Details:
| Attribute | Value |
|-----------|-------|
| Target | LRRK2 mRNA |
| Mechanism | RNase H-mediated mRNA degradation |
| Phase | Phase 1 |
| NCT Number | NCT03976375 |
| Route | Intrathecal |
| Indication | Parkinson's disease (LRRK2 mutation carriers and sporadic PD) |
Development:
For more detail, see [LRRK2 Antisense Oligonucleotide Therapies](/therapeutics/lrrk2-antisense-therapy).
Ionis' proprietary antisense technology platform enables the design of ASOs that specifically bind to target RNA sequences, leading to degradation of the target mRNA and reduced protein production. The company's advanced chemistries, including 2'-O-methoxyethyl (2'-MOE) and phosphorodiamidate morpholino oligomers (PMOs), improve drug delivery and efficacy[@geary2003].
| Mechanism | Description | Applications |
|-----------|-------------|--------------|
| RNase H-mediated degradation | ASO binds to target mRNA, RNase H cleaves the RNA strand | Most common mechanism for gene knockdown |
| Steric blockade | ASO blocks ribosomal translation without degrading mRNA | Splicing modulation, read-through |
| RISC-mediated | siRNA-like mechanism using Argonaute proteins | Gene silencing |
Ionis has maintained strong financial backing through its strategic partnerships and independent funding:
Ionis' ASO programs target several key mechanisms in neurodegenerative diseases: