Our aim was to evaluate the respective value of CD26, CD7 and KIR3DL2 expression on CD4<sup>+</sup> T cells and total lymphocytes at initial diagnosis of SS.
A multi-cohort, phase 2 trial (TELLOMAK) is underway to confirm the activity in patients with Sézary syndrome and explore the role of IPH4102 in other subtypes of T-cell lymphomas that express KIR3DL2.
Moreover, KIR3DL2 immunostaining allowed the assessment of treatment efficiency and specificity toward tumor cells, the detection of the residual disease following treatment, and the occurrence of relapse, even though patients clinically experienced complete remission and/or undetectable circulating Sézary cells by cytomorphologic analysis.<b>Conclusions:</b> We show that KIR3DL2 expression is the most sensitive diagnostic criterion of Sézary syndrome when compared with all other available biological criteria.
These characteristics have implicated KIR3DL2 in several pathologies: ankylosing spondylitis and cutaneous T-cell lymphomas such as Sézary syndrome, CD30<sup>+</sup> cutaneous lymphoma, and transformed mycosis fungoides.
In light of these findings, CD158k/KIR3DL2 transcripts appear to be a unique molecular marker of SS in skin samples, allowing differential diagnosis with benign EID in routine practice.
Identification of the malignant cells in Sézary syndromecannot be achieved by T-cell clonality studies or by TCR Vbeta monoclonal antibody (mAb) analysis alone; it also relies on CD158k phenotyping.