PD1/PDL1 immune checkpoint blockade provides clinical benefits in a variety of solid tumors. Scarce are data on PD1/PDL1 pathway and immunological infiltrates in osteosarcoma. We hypothesized that immune infiltrates were associated with superior survival, and examined a primary osteosarcoma tissue microarrays (TMA) to test this hypothesis.
Biopsies from 129 pts, prospectively treated from 04/2001 to 11/2006 (protocol ISG-OS1), were analyzed. TMA from representative areas were assembled. Clinical and pathological characteristics at diagnosis, immunological characterization (CD8, CD4, CD3, FOXP3, CD20, CD68) of TME, PD-1 expression on TME, and PD-L1 both on tumor (t) cells and TME were correlated with pts outcome.
86/129 pts had adequate staining for all markers. Median age: 16 (range 4-39); high LDH: 36/86; high alkaline phosphatase (AP): 18/86. All pts underwent neoadjuvant chemotherapy and surgery. A good pathologic response (≥90% necrosis) was achieved by 45/86 pts. The IHC results are reported in the table.
While this study confirms the importance of good pathologic response,our findings support the hypothesis that CD8+ T effector cells presence in TME at diagnosis confers superior survival for pts with localized osteosarcoma.
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All authors have declared no conflicts of interest.