Myelodysplastic syndromes (MDS) are a group of clonal neoplasms characterized by ineffective hematopoiesis. Hypomethylating agent (HMA) therapy is one of the mainstays of MDS therapy. Failure of HMA therapy is related to poor outcome; hence, new therapeutic approaches are warranted in these patients. In MDS, the immune system has a pivotal role in modulation of hematopoiesis and clonal expansion. In neoplastic conditions, immune checkpoint (PD-1 and CTLA4 molecules) hide tumor cells from immune surveillance. Identification of the pattern of expression of these molecules in MDS provides an interesting alternative within clinical trials.
MATERIALS AND METHODS:
We describe the clinicopathologic correlations by morphology, immunohistochemistry (PD-L1) and flow cytometry immunophenotypic analysis in an MDS patient treated with immune checkpoint PD-1 inhibitor.
Bone marrow (BM) morphology, differential counts and aberrant flow markers were assessed before and after anti PD-1 inhibitor therapy. At baseline, BM showed severe trilineage dysplasia with decreased granulopoiesis; after therapy, BM showed normal trilineage hematopoiesis. A decrease in PD-L1 expression, by manual and automatic analysis, was also noted from 15% to 5% after 26 months of treatment. The findings correlated with the recovery of peripheral blood counts and transfusion independency.
BM morphology and PD-L1 expression by immunohistochemistry can be used to assess treatment response in immune checkpoints therapy.