JAK inhibition for CD3^- CD4⁺ lymphocytic-variant hypereosinophilic syndrome

Area of Science:

• Hematology
• Immunology
• Dermatology

Background:

• Lymphocytic-variant hypereosinophilic syndrome (L-HES) presents a therapeutic challenge, particularly for patients refractory to high-dose steroids or other treatments.
• Effective alternatives are crucial for managing L-HES, especially cases with significant cutaneous involvement and persistent eosinophilia.

Purpose of the Study:

• To evaluate the efficacy and safety of Janus kinase (JAK) inhibitors as a treatment option for patients with CD3⁻ CD4⁺ lymphocytic-variant hypereosinophilic syndrome (L-HES).

Main Methods:

• A case series involving five adult L-HES patients (44-66 years) with cutaneous manifestations and persistent eosinophilia, who were treated with JAK inhibitors (tofacitinib or ruxolitinib).
• Assessment of clinical response, absolute eosinophil counts, prednisone withdrawal, clone size, and adverse events over a 3-13 month follow-up period.

Main Results:

• All five patients achieved complete clinical remission within three months of JAK inhibitor treatment, enabling prednisone withdrawal in four patients.
• Ruxolitinib led to normalization of absolute eosinophil counts, while tofacitinib resulted in partial reduction; switching to ruxolitinib maintained remission.
• No adverse events were reported during the follow-up, and the clone size remained stable in all patients.

Conclusions:

• JAK inhibitors demonstrate significant efficacy and a favorable safety profile for treating L-HES, offering a viable alternative for refractory cases.
• Further prospective clinical trials are warranted to confirm these findings and establish JAK inhibitors as a standard treatment for L-HES.