TY - JOUR AU - tandon, sneha AU - Weitzman , Sheila AU - Joyce, Brooklyn AU - Maguire, Bryan AU - Stephens, Derek AU - Whitlock, James AU - Hawkins , Cynthia AU - Ngan, Bo-Yee AU - Abla , Oussama PY - 2023/04/27 Y2 - 2024/03/28 TI - EXPRESSION AND CLINICAL CORRELATION OF PD-1/PD-L1 AND VE1(BRAFP.V600E) IN PEDIATRIC LANGERHANS CELL HISTIOCYTOSIS JF - Mediterranean Journal of Hematology and Infectious Diseases JA - Mediterr J Hematol Infect Dis VL - 15 IS - 1 SE - Original Articles DO - 10.4084/MJHID.2023.035 UR - https://www.mjhid.org/mjhid/article/view/5164 SP - e2023035 AB - <p><strong>Background</strong>: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm with a wide spectrum of clinical presentations. Programmed Cell Death-1 (PD-1) receptor and its ligand (PD-L1)&nbsp;&nbsp; are overexpressed in LCH, but their clinical significance is unknown. We performed a clinical correlation study of PD-1/PD-L1 and VE1(BRAFp.V600E) expression in 131 children with LCH.</p><p><strong>Methods:</strong> A total of 111 samples were tested for PD-1/PD-L1 and 109 for VE1(BRAFp.V600E) mutant protein by immunohistochemistry.</p><p><strong>Results:</strong> PD-1, PD-L1 and VE1(BRAFp.V600E) positivity was observed in 40.5%, 31.53% and 55%, respectively.&nbsp; PD-1/ PD-L1 expression showed no significant effect on the rate of disease reactivations, early response to therapy or late sequelae. The 5-year EFS was not statistically different between patients with PD-1 positive compared to those with PD-1 negative tumours (47.7% vs.58.8%, p=0.17). Similar 5-year EFS rates were also seen in those who were PD-L1 positive compared to PD-L1 negative cases (50.5% vs.55.5%, p=0.61). VE1(BRAFp.V600E) positivity was associated with a significantly higher frequency of risk-organ involvement (p=0.0053), but no significant effect on early response to therapy or rates of reactivations or late sequelae.</p><p><strong>Conclusions:</strong> Our study showed no significant correlation between VE1(BRAFp.V600E) expression, PD-1 and PD-L1 a clinical outcome in pediatric LCH.</p> ER -