Expression and prognostic values of PD-1, PD-L1 and IDO-1 in sinonasal malignant mucosal melanoma

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Objective: To investigate the correlation between the expression of programmed death-1(PD-1), PD ligand-1(PD-L1), indoleamine 2, 3-dioxygenase 1(IDO-1) and clinical parameters in sinonasal malignant mucosal melanoma (SNM). Methods: Samples from 86 SNM patients who did not receive immune-targeted therapy and radio-chemotherapy were analyzed for PD-1, PD-L1, and IDO-1 expression by immunohistochemistry. Results: High clinical/pathologic staging, brain metastases and advanced age were independent risk factors of poor prognosis. The overall survival rate of SNM without pigment was lower than that with pigment. PD-1, PD-L1 and IDO-1 expression was not correlated with tumor pigmentation, but correlated with different primary site.PD-1, PD-L1 and IDO-1 were expressed in 47.6% (41/86), 53.5% (46/86) and 58.1% (50/86)of SNM samples respectively. PD-1 was associated with brain metastasis. Negative expression of PD-1(P=0.031) and IDO-1(P=0.017 9) correlated with worse disease-free survival. No significant association was found between PD-L1 and prognosis. For stages Ⅲ, ⅣA and ⅣB patients, PD-1 expression was associated with better outcome (P=0.025), but PD-L1 negative and IDO-1 positive patients hadworse outcome (P>0.05). PD-1 positive and IDO-1 negative stage ⅣC patients had poorer overall survival. Conclusions: In SNM patients, clinical/pathologic staging, brain metastases, age and pigmentation were prognostic indicator. IDO-1 and PD-1 can also be used as reference to evaluate prognosis. Anti-IDO-1 targeted therapy may be suitable for middle to late stage patients, while advanced stage patients might benefit from anti-PD-1 targeted therapy. PD-1/PD-L1 and IDO-1 may be considered as joint targeted therapy.The predictive value of PD-L1 requires further study.