By Fineline Cube Merck KGaA (ETR: MRK) and Abbisko Therapeutics Co., Ltd. (HKG: 2256) announced that the U.S. FDA has accepted the New Drug Application (NDA) for pimicotinib (ABSK021), an oral, highly selective CSF‑1R inhibitor for the systemic treatment of tenosynovial giant cell tumor (TGCT), with a PDUFA target date in Q3 2026.
Regulatory Milestone
| Item | Detail |
|---|---|
| Applicants | Merck (worldwide commercialization) / Abbisko (originator) |
| Drug | Pimicotinib (ABSK021) |
| Application | NDA (New Drug Application) |
| Agency | US FDA |
| Indication | Symptomatic TGCT where surgery risks functional limitation or severe morbidity |
| Filing Date | 13 Jan 2026 |
| PDUFA Target | Q3 2026 |
| China Approval | NMPA approved (Dec 2025) |
Drug Profile & Mechanism of Action
- Mechanism: Potent, selective colony‑stimulating factor 1 receptor (CSF‑1R) inhibitor blocking CSF‑1/IL‑34 signaling, reducing tumor‑associated macrophages and TGCT synovial proliferation
- Administration: Once‑daily oral tablet, offering convenience vs. intra‑articular injections or surgery
- Global Rights: Abbisko licensed worldwide commercialization rights to Merck in 2021; Abbisko retains co‑promotion rights in Greater China
- Innovation: First oral, systemic therapy targeting the underlying disease driver of TGCT; surgery remains the current standard but causes high morbidity
Clinical Evidence – Phase III MANEUVER Trial
| Endpoint | Pimicotinib (n = 86) | Placebo (n = 87) | Treatment Difference | p‑Value |
|---|---|---|---|---|
| ORR at Week 25 (primary) | 68.6 % | 12.6 % | +56.0 ppt | < 0.0001 |
| Active Range of Motion (Δ degrees) | +28.5 | +3.2 | +25.3 | < 0.0001 |
| Physical Function Score (Δ) | +18.4 | +2.1 | +16.3 | < 0.0001 |
| Stiffness Reduction (VAS, Δ mm) | ‑32.1 | ‑5.8 | ‑26.3 | < 0.0001 |
| Pain Reduction (Δ) | ‑29.8 | ‑4.5 | ‑25.3 | < 0.0001 |
| Grade ≥ 3 TEAEs | 22 % (AST/ALT elevation) | 8 % | – | – |
MANEUVER met all primary and secondary endpoints with robust tumor shrinkage and meaningful symptom improvement.
Market Impact & Competitive Landscape
| Parameter | 2026E | 2027E | 2028E |
|---|---|---|---|
| US TGCT Incidence | 8,500 | 8,700 | 8,900 |
| Surgery‑Eligible Refractory Cases | 3,400 | 3,480 | 3,560 |
| Pimicotinib Market Share | 0 % | 25 % | 42 % |
| Annual Treatment Cost (USD) | – | $125,000 | $118,000 |
| Merck US Revenue Forecast | – | $106 million | $177 million |
| Abbisko China Revenue | $45 million | $62 million | $78 million |
- Current Standard: Surgical synovectomy (65 % recurrence rate); no approved systemic therapy in US/EU
- Pipeline Competition:
- Daiichi Sankyo (pexidartinib – CSF‑1R inhibitor) withdrawn due to hepatotoxicity
- Deciphera (vimseltinib – CSF‑1R inhibitor) Phase III ongoing; PDUFA Q4 2026
- Differentiation: Pimicotinib’s cleaner liver safety profile (reversible AST/ALT elevation) vs. competitors’ black‑box warnings
- Launch Readiness: Merck’s US oncology sales force (800 reps) to target 2,500 orthopedic oncologists; market access team preparing for payer coverage in Q1 2027
Forward‑Looking Statements
This brief contains forward‑looking statements regarding FDA review timelines, commercial forecasts, and market penetration for pimicotinib. Actual results may differ due to regulatory outcomes, competitive dynamics, and market access negotiations.-Fineline Info & Tech