Abstract 2544: Identification of immune signatures predicting for clinical outcome measured by flow-cytometry and immunogenetic analysis of PBMCs from breast cancer patients treated with docetaxel alone or docetaxel plus vaccine
Authors: Grenga Italia , Ascierto Maria Libera , Donahue Renee N. , Gulley James L. , Heery Christopher R. , Madan Ravi A. , Schlom Jeffrey , Wang Ena , Farsaci Benedetto 
Published: May 2015

Background: Therapeutic vaccination is emerging as a potential treatment to prolong cancer patient survival. However, there are not markers available to identify patients that could benefit from this treatment. The aim of this retrospective study was to identify PBMC immune cell subsets and immunogenetic signatures of metastatic breast cancer patients that, before treatment, could predict for clinical outcome.

Methods: We applied multi-color flow-cytometry analysis of PBMCs harvested prior to treatment from metastatic breast cancer patients (n=43) enrolled in a randomized phase II trial of docetaxel alone or docetaxel + vaccine (PANVACTM-V and PANVACTM-F). The frequency of more than 200 immune sub-populations was measured using an LSR-II (BD Biosciences) and analyzed by FlowJo (TreeStar). A peripheral immunoscore was calculated based on the correlation of each subset with PFS. From the same PBMC samples, gene expression analyses were performed using GeneChip Human Gene 1.0 ST Arrays (Affymetrix). Data set were analysed using Partek Genomic Suite and Ingenuity Pathway Analysis software.

Results: The flow-cytometry analysis showed that, in the vaccine plus docetaxel arm, 10 immune subsets from PBMCs at baseline correlated with PFS; these cell subsets were used for the calculation of the peripheral immunoscore. Patients with a peripheral immunoscore above the median showed a longer PFS compare to patients with a peripheral immunoscore below the median only in the docetaxel plus vaccine arm but not in the docetaxel alone. The survival prediction analysis based on gene expression identified 7 genes that best distinguish (p&lt;0.001) long PFS from short PFS patients that received docetaxel + vaccine. These same genes were not statistically correlated (p&gt;0.05) with PFS in patients treated with docetaxel alone.

Conclusions: The calculation of a peripheral immunoscore by flow-cytometry and associated gene expression analysis of PBMCs before treatment, could be used for the identification of a specific immune signature of cancer patients that will most likely benefit from vaccine immunotherapy. Larger prospective trials are necessary to validate and confirm the potential application of these methods to other patient populations treated with immunotherapy.

Citation Format: Italia Grenga, Maria Libera Ascierto, Renee N. Donahue, James L. Gulley, Christopher R. Heery, Ravi A. Madan, Jeffrey Schlom, Ena Wang, Benedetto Farsaci. Identification of immune signatures predicting for clinical outcome measured by flow-cytometry and immunogenetic analysis of PBMCs from breast cancer patients treated with docetaxel alone or docetaxel plus vaccine. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2544. doi:10.1158/1538-7445.AM2014-2544