Introduction & Objectives

Targeted therapies for cutaneous T-cell lymphoma (CTCL) are limited and curative approaches are still lacking. Relapses and drug-induced side effects are major challenges in the therapeutic management of CTCL patients, resulting in an urgent need for new, effective therapies. Expression of CD30 receptor is usually restricted to a small population of activated B- and T-cells, but is also found in hematologic malignancies, such as CTCL. In mycosis fungoides (MF) its expression seems to be associated with advanced disease stage and large-cell transformation. However, the functional role of CD30 in CTCL remains unknown. Consequently, this study aims to determine 1) CD30 and CD30 ligand (CD30L) expression in CTCL cell lines and primary CD4-positive cells from CTCL patients, 2) the dynamics of CD30 expression over time and after treatment, 3) CD30 function in vitro, ex vivo and in vivo, 4) mechanisms involved in CD30 signaling.

Materials & Methods

The CTCL cell lines HH, SeAx and HUT-78 were used for in vitro experiments. For ex vivo analysis, primary CD4-positive T-cells isolated from fresh blood samples of patients with Sezary syndrome were used. Cells were challenged with dimethyl fumarate for 24 hours. CD30 was stimulated via its natural ligand. Methods used for expression and pathway analysis were FACS, western blot, PCR and luciferase assay. For in vivo experiments, CTCL cells were suspended in PBS/Matrigel (1:1, vol/vol) and injected intradermally into the right flank of female NOD/SCID/Il2Rg null (NSG) mice. After development of tumors, CD30L was injected into the lesions.

Results

We found that CD30 activation can influence viability of CTCL cells in vitro, which is currently under investigation in an in vivo setting. Involved mechanisms include the MEK/ERK and NF-κB pathway. The highest CD30 expression was detected in the HH cell line. The primary CD4-positive cells analyzed so far were negative for CD30 surface expression. However, intracellular CD30 protein was detectable via western blot. CD30 levels were influenced by cell culture conditions in HH cells and significantly reduced upon therapeutic NFκB inhibition in HH, SeAx and HUT-78 cells.

Conclusions

Our results indicate a therapeutic potential of CD30 receptor stimulation as a new targeted therapy in CD30-positive MF in vitro, which has to be proven in vivo. Furthermore, we found a dynamic nature of CD30 expression in CTCL, which might account for the described effectiveness of the antibody-drug conjugate brentuximab vedotin directed to CD30 also in patients diagnosed as CD30 low-expressing.