Selective JAK Inhibition in RA vs PV

Tofacitinib induced remission of rheumatoid arthritis but spared JAK2-driven polycythemia vera in a single case report.

By
Julia Cipriano
February 13, 2026
3 min

Conexiant

Objective:

To evaluate the effects of the selective JAK inhibitor tofacitinib in a patient with both rheumatoid arthritis (RA) and polycythemia vera (PV).

Approach:

Key Findings:

Tofacitinib demonstrated significant rheumatologic efficacy in controlling RA symptoms.
Hematologic parameters related to PV remained stable, indicating limited impact on PV-related conditions.
The patient achieved clinical and ultrasonographic remission of RA within 3 months of tofacitinib initiation.

Interpretation:

Tofacitinib effectively manages RA symptoms while maintaining hematologic safety in patients with concurrent PV, highlighting the need for JAK2-specific therapies for PV.

Limitations:

Only a single case report, limiting generalizability.
No prior studies on the use of JAK inhibitors in patients with both RA and PV.

Conclusion:

Tofacitinib is effective for RA in patients with concomitant PV, but its limited effect on erythrocytosis suggests the necessity for targeted JAK2 therapies.