targetsTarget

CD25 (IL-2 receptor alpha)

CD25 is the part of the interleukin-2 receptor found on activated T cells and on some lymphoma cells; denileukin diftitox uses it as a doorway to deliver a toxin.

CD25, the alpha chain of the high-affinity interleukin-2 receptor (IL2RA), is expressed on activated T cells, regulatory T cells and the malignant cells of cutaneous T-cell lymphoma, adult T-cell leukaemia/lymphoma and some Hodgkin and B-cell lymphomas. Denileukin diftitox, a fusion of IL-2 with diphtheria toxin fragments, binds CD25-expressing cells and kills them by blocking protein synthesis; it was approved in 1999, withdrawn in 2014 for manufacturing reasons and reapproved as Lymphir in 2024 for relapsed or refractory stage I to III CTCL. Anti-CD25 antibodies (basiliximab, daclizumab) are used in transplantation and were studied in leukaemia and for regulatory T-cell depletion.

CD25 (IL-2 receptor alpha): what it is and how drugs act on it · animated generic schematic, not to scale

Target · the protein and the cell it sits on
Drug · antibody, small molecule, cell or radioligand
Effect · signal, damage or kill

In plain words · CD25 is the part of the interleukin-2 receptor found on activated T cells and on some lymphoma cells; denileukin diftitox uses it as a doorway to deliver a toxin.

1 · What it is
CD25 is the part of the interleukin-2 receptor found on activated T cells and on some lymphoma cells; denileukin diftitox uses it as a doorway to deliver a toxin.
2 · What goes wrong in cancer
CD25 confers high-affinity IL-2 binding; its density on regulatory T cells makes it a candidate for depleting immunosuppressive cells in the tumour microenvironment.
3 · How drugs use it
1 product aims at CD25 (IL-2 receptor alpha): immunotoxins. Because it sits on the outside of the cell, it can be reached from the bloodstream: antibodies flag the cell, ADCs deliver a toxin, radioligands deliver radiation, and CAR-T or bispecifics bring a T cell.

Full dossier: hotspots, trials, resistance, assays, models, open questions →

Elsewhere

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Biology

CD25 confers high-affinity IL-2 binding; its density on regulatory T cells makes it a candidate for depleting immunosuppressive cells in the tumour microenvironment.

Where it is found

Cutaneous T-cell lymphoma (about half of cases express CD25)
Adult T-cell leukaemia/lymphoma
Hodgkin lymphoma (Reed-Sternberg cells)

Class

surface antigen · IL2RA

Products

1top

ApprovedIL-2 receptor-directed cytotoxin (fusion protein)

Denileukin diftitox · Lymphir

Denileukin diftitox (Lymphir) is an infusion that uses the interleukin-2 signal as a homing device to deliver a bacterial toxin into cutaneous T-cell lymphoma cells. It was withdrawn in 2014 and returned in an improved form in 2024.