The CD47 "don't eat me signal" is highly expressed in human ovarian cancer

Abstract

Objectives: The CD47 "don't eat me" signal allows tumor immune evasion. We tested the association of CD47 expression with outcomes in EOC.

Methods: CD47 expression was examined within the TCGA database for ovarian carcinoma. For validation, IHC was performed on a TMA consisting of specimens from 265 patients with EOC. The medical records of the patients were also retrospectively reviewed to correlate demographic and survival data.

Results: CD47 was amplified in 15/316 (5%) ovarian serous cancers in TCGA. In the validation cohort, the majority of patients had stage III/IV disease (208/265, 78.4%). CD47 expression was seen in 210/265 (79.2%). Patients were categorized into CD47hi (129/265; 48.7%) versus CD47lo (136/265; 51.3%). Patients with CD47lo tumors were more likely to have a complete response to adjuvant therapy than CD47hi (65% vs 50%, p=0.026). Although there was a trend towards an increase in median OS (37.64 vs 45.26months, p=0.92) in the CD47lo group compared with CD47hi, the difference was not significant.

Conclusions: CD47 is expressed at high frequency in EOC. Patients with CD47lo EOC had a better treatment response to standard therapy, and trended towards improved OS. This demonstrates that while CD47 may be an immunologic shield that may be considered for targeted therapies, it is likely that it operates in concert with other mechanisms of immune evasion. Future studies to evaluate CD47 expression with other known mechanisms of immune escape in the tumor microenvironment may help further define its role.

Keywords: CD4(+) T cells; CD47; CD8(+) T-cell activation; IFN-γ; NY-ESO-1; Ovarian cancer; SIRPα; anti-tumor effect.