Blocking STAT3/5 through direct or upstream kinase targeting in leukemic cutaneous T‐cell lymphoma

A–C

Spearman correlation analysis using CNA log₂ ratios and the percentage of clonal CD3⁺ cells detected in patients for (A) STAT3, (B) STAT5A, and (C) STAT5B.

D–F

RT–qPCR expression data of (C) STAT3, (D) STAT5A, and (E) STAT5B genes from whole PBMCs isolated from patient blood (n = 5) or healthy controls (n = 9). GAPDH expression was used for normalization. Statistical significance was calculated using a two‐tailed unpaired t‐test. P‐value: < 0.01 (**) and < 0.0001 (****). One experiment was performed in technical triplicates. The bold dashed line in the middle of the violin plot denotes the median value, while the thin dotted lines denote the interquartile range.

G

Immunoblotting for total STAT3/5 protein isolated from the respective whole PBMCs from patient blood (n = 3) or healthy controls (n = 3). HSC70 was used as loading control. One experiment was performed.

H

Representative image of H&E, CD3, pY‐STAT5 single staining, and CD3/pY‐STAT5 double staining on skin biopsy tissue from P3 (n = 1), which demonstrates infiltration of CD3⁺ pY‐STAT5⁺ (13.45%) cells into the dermal and subcutaneous layer of the skin. Arrows indicate pY‐STAT5⁺ single and CD3⁺ pY‐STAT5⁺ cells.

I–M

Quantification of IHC staining from skin‐biopsy sections of L‐CTCL patients (n = 6) and healthy individuals (n = 5) depicted in Appendix Fig S3. As the number of STAT5A/B‐positive cells was negligible (less than 0.03/per mm²) in healthy skin biopsy sections, healthy control samples were considered negative for pY‐STAT5, and levels were set to 0. Statistical significance was calculated using an unpaired Welch's t‐test. P‐value: < 0.05 (*). The bold dashed line in the middle of the violin plot denotes the median value, while the thin dotted lines denote the interquartile range.

Figure 2. STAT3/5 copy number gain correlates with disease clonality and results in STAT3/5 overexpression and hyperactivation.