JAK2 Inhibitors
13 drugsAbout JAK2
Janus Kinase 2 (JAK2) is a protein kinase crucial for cell growth, differentiation, and immune function signaling pathways. Dysregulation of these pathways can lead to autoimmune disorders and cancers. Activation of JAK2 is likely beneficial based on genetic evidence.
Human genetic studies provide strong validation for JAK2 as a therapeutic target (max score 0.82), with variants linked to hematologic disease (0.82), thrombocythemia 3 (0.81), and splenomegaly (0.79). Loss-of-function variants are associated with increased disease risk.
JAK2 is targeted by 13 FDA-approved small molecule drugs, including XELJANZ, RINVOQ, and INREBIC. These drugs are used to treat conditions in immunology (4 drugs) and other therapeutic areas (9 drugs).
JAK2 Genetic Evidence Strong
JAK2 has strong genetic support with a max score of 0.82 across 71 diseases.
Strong genetic support increases the likelihood of clinical success for JAK2-targeting therapies.
💡 Why activation?
- • Loss-of-function variants increase disease risk (OR > 1) — restoring function may help
- • 100% directional consistency across 3 traits
- • Strong signal in hematologic disease, genetic, familial or congenital disease pathways
Cross-Disease Effects
Trade-off: LowDirection of Effect
100% alignedEvidence Across Diseases
20 totalGWAS and other genetic studies link JAK2 to 71 diseases.
Loss-of-function causes disease; activation may help
Loss-of-function causes disease; activation may help
Effect Sizes
Genetic effect on disease risk. OR<1 or β<0 = loss-of-function is protective (inhibiting target may help).
🔗 Colocalization Evidence 20 strong
max H4: 1.00eQTL/pQTL signals for JAK2 colocalize with these GWAS traits, providing causal evidence that gene expression changes drive disease risk.
Understanding these scores
Association Score (0-1): Combines all evidence types (genetic, literature, drugs, animal models). Higher = more evidence linking target to disease. This is a ranking heuristic, not a confidence score.
L2G Score: Open Targets uses a machine learning model (Locus-to-Gene) to predict which gene is causal at each GWAS locus. L2G=0.5 means ~50% probability of being the causal gene. Only associations with L2G > 0.05 are included.
Odds Ratio (OR): From gene burden studies (UK Biobank, AstraZeneca PheWAS). Measures how loss-of-function variants affect disease risk. OR<1 = protective (inhibiting target may help), OR>1 = risk (losing function causes disease).
Beta (β): Effect size for continuous traits. β<0 = protective, β>0 = risk.
Clinical Translation (~1.8x): Based on Nelson et al. 2015: drug targets with genetic evidence have ~2x higher success rates in clinical trials. We estimate: Strong support (score ≥0.7) → ~1.8x, Moderate (0.3-0.7) → ~1.3x, Weak → baseline.
Colocalization (H4): Tests whether a GWAS signal and an eQTL/pQTL signal share the same causal variant. H4 is the posterior probability that both traits are associated AND share a causal variant. H4 > 0.8 = strong evidence that gene expression/protein levels drive disease risk. This links genetic variation → gene expression → disease, supporting the target-disease connection.
Top JAK2 Drugs
Eleven companies have approved JAK2 drugs, with PF PRISM CV and AbbVie as top players.
The presence of many players suggests a competitive market, requiring strong differentiation for new entrants.
| Drug | Company | Approved | Indications |
|---|---|---|---|
| XELJANZ XR | Pfizer | 2016 | 5 |
| RINVOQ LQ | AbbVie | 2024 | 4 |
| INREBIC | Bristol-Myers Squibb | 2019 | 3 |
| OLUMIANT | Eli Lilly | 2018 | 3 |
| OPZELURA | INCYTE CORP | 2021 | 2 |
| GAVRETO | RIGEL PHARMS | 2020 | 2 |
| OJJAARA | GSK | 2023 | 2 |
| ANZUPGO | LEO PHARMA AS | 2025 | 1 |
| VONJO | SOBI | 2022 | 1 |
| LEQSELVI | Sun Pharma | 2024 | 1 |
JAK2 Drug Modality Landscape
Modalities
Routes of Administration
JAK2 is amenable to small molecule drugs, with oral options available for convenient dosing.
Explore alternative modalities like antibodies or fusion proteins to differentiate from existing therapies.
JAK2 Clinical Trials 729 trials
Phase 1-4 trials started in 2008 or later that test an FDA-approved drug acting on JAK2. Source: ClinicalTrials.gov. How we count
Completion by Phase
| Phase | Total | Completed | Stopped | Active | Completion |
|---|---|---|---|---|---|
| Phase 1 | 215 | 104 | 30 | 81 | 78% |
| Phase 2 | 290 | 117 | 49 | 124 | 70% |
| Phase 3 | 171 | 84 | 25 | 62 | 77% |
| Phase 4 | 53 | 15 | 4 | 34 | 79% |
Top Sponsors
By Modality
Top Conditions
Phase 3 Readout Calendar Pro
8 Phase 3 trials testing approved JAK2 drugs across all sponsors.
Coverage: trials whose intervention is an approved drug targeting JAK2. Pre-approval candidates with development codes (e.g. AZD0901, MK-7240) are not yet linked. Anchored on CT.gov primary completion date.
JAK2 Drug Approval Timeline (2011 - 2025)
JAK2 has seen approvals spanning 15 years, from 2011 (JAKAFI) to 2025 (ANZUPGO).
The continued approvals suggest sustained interest, but also potential market saturation in certain indications.
Pro Intelligence Preview
Deep insights for drug target analysis
Competitive Landscape
- • 10 companies competing
- • Market share by company
Full Drug Portfolio
- • All 13 approved drugs
- • Approval dates & indications
Genetic Validation
- • Full genetic evidence table
- • Effect sizes & directions
Approval Timeline
- • Full 13-drug timeline
- • First-of-modality markers
Clinical Trials Analysis
- • Sponsors: 257 (55 companies)
- • Completion rates by condition
Full summary • All drugs • Genetic evidence • Trials • Timeline
How We Count Trials
- Trials: phase 1-4 interventional trials on ClinicalTrials.gov that started in 2008 or later and test an FDA-approved drug acting on JAK2. A trial counts if an approved drug acting on JAK2 is in any arm, including as a comparator, and a trial that tests two such drugs counts once. Trials that test only unapproved drugs are not counted. A trial listed as phase 1/2 counts as phase 1, and phase 2/3 as phase 2.
- Active: recruiting, not yet recruiting, enrolling by invitation, or active and no longer recruiting.
- Completion rate: of the trials that have ended, the share marked Completed rather than Terminated or Withdrawn. Completed means the trial ended as planned; it does not mean the drug worked. Suspended trials are not counted as ended.
- Stopped: terminated or withdrawn. Trials stop for many reasons, including slow enrolment and business decisions, not only safety or efficacy.
- Sponsors: the lead sponsor of each trial. Companies are the sponsors ClinicalTrials.gov classes as industry; the rest are universities, hospitals, cooperative groups, government bodies and individuals.