Highlights 

  • FDA grants Breakthrough Therapy designation to INCA033989 for Type 1 CALR-mutant ET. 
  • Therapy shows early signs of platelet normalization in Phase 1 data. 
  • Incyte plans a Phase 3 program covering all CALR mutation types in mid-2026. 
  • Updated ET and MF data to be presented at the 2025 ASH Annual Meeting. 
  • INCA033989 aims to spare healthy cells by precisely targeting mutCALR-driven disease. 

Incyte (NASDAQ:INCY) has announced that the U.S.FDAhas granted Breakthrough Therapy designation to INCA033989, the company’s first-in-class monoclonal antibody designed to target mutant calreticulin (mutCALR). The designation applies to patients with essential thrombocythemia who carry a Type 1 CALR mutation and are resistant or intolerant to at least one cytoreductive therapy. 

ET is a chronic myeloproliferative neoplasm marked by persistently elevated platelet counts due to abnormal bone marrow activity. CALR mutations, among the most common oncogenic drivers in ET, appear in roughly 25 percent of patients. Type 1 CALR mutations—present in more than half of CALR-mutant ET cases—carry the greatest risk of progression to myelofibrosis. 

According to Pablo J. Cagnoni, M.D., President and Head of Research and Development at Incyte, the designation accelerates development efforts and reflects the meaningful therapeutic promise of INCA033989 for a patient group with limited treatment options. 

Encouraging Early Clinical Data Presented at EHA and Heading to ASH 

The FDA’s decision was supported by Phase 1 data evaluating INCA033989 in patients with Type 1 CALR mutations. These preliminary results, presented earlier this year at the 2025 European Hematology Association Congress, revealed that the investigational antibody was well-tolerated and delivered rapid and sustained platelet count normalization across evaluated doses. Higher doses demonstrated greater platelet responses in both Type 1 and non-Type 1 mutation groups. 

Incyte will present updated findings at the 2025 ASH Annual Meeting in Orlando, including new data in both essential thrombocythemia and myelofibrosis. The company notes that INCA033989’s mutCALR-specific targeting may spare healthy cells, offering a precisely directed approach distinct from broader cytoreductive strategies. 

Following discussions with regulatory agencies, Incyte intends to initiate a registrational Phase 3 program in mid-2026, evaluating the therapy in ET patients with either Type 1 or non-Type 1 CALR mutations who have inadequate response or intolerance to existing treatments. 

Expanding Pipeline Focused on MPN Innovation 

Incyte continues to advance a pipeline dedicated to oncology, inflammation and autoimmunity, with a particular focus on myeloproliferative neoplasms. The company is recognized for developing targeted therapies that address disease biology while aiming to maintain healthy cell function. INCA033989 is positioned as a key component of this next wave of mutCALR-focused innovation. 

Conclusion 

The FDA’s Breakthrough Therapy designation for INCA033989 positions Incyte to accelerate development of a therapy that could meaningfully shift the treatment landscape for CALR-mutant essential thrombocythemia. With encouraging early data, strong mechanistic rationale, and a Phase 3 program on the horizon, the company is poised to advance a next-generation therapeutic strategy for patients with limited current options. 

Incytes’ shares closed at USD 102.52, marking a 2.05% increase from the prior session.