The detection of CTCs prior to and during therapy is an independent and strong prognostic marker, and it is predictive of poor treatment outcome. A major challenge is that different technologies are available for isolation and characterization of CTCs in peripheral blood (PB). We compare the CellSearch system and AdnaTest BreastCancer Select/Detect, to evaluate the extent that these assays differ in their ability to detect CTCs in the PB of MBC patients. CTCs in 7.5 ml of PB were isolated and enumerated using the CellSearch, before new treatment. Two cutoff values of 2 and 5 CTCs/7.5 ml were used. AdnaTest requires 5 ml of PB to detect gene transcripts of tumor markers (GA733-2, MUC-1, and HER2) by RT-PCR. AdnaTest was scored positive if 1 of the transcript PCR products for the 3 markers were detected at a concentration 0.15 ng/ll. A total of 55 MBC patients were enrolled. 26 (47%) patients were positive for CTCs by the CellSearch (2 cutoff), while 20 (36%) were positive (5 cutoff). AdnaTest was positive in 29 (53%) with the individual markers being positive in 18% (GA733-2), 44% (MUC-1), and 35% (HER2). Overall positive agreement was 73% for CTC2 and 69% for CTC5. These preliminary data suggest that the AdnaTest has equivalent sensitivity to that of the CellSearch system in detecting 2 or more CTCs. While there is concordance between these 2 methods, the AdnaTest complements the CellSearch system by improving the overall CTC detection rate and permitting the assessment of genomic markers in CTCs.

Highlights d High rate of NF1 loss in the R0 compared to neoadjuvant chemotherapy (NACT) group d Lower chromothripsis-like pattern and higher neoantigens in the R0 versus NACT group d Increased number of infiltrated T cells and decreased macrophages in the R0 group d Significant transcriptomic and proteomic variations between HGSC subgroups

SUMMARY Follicular helper T cells (T FH ) are critical for vaccine and infection elicitation of long-lived humoral immunity, but exaggerated T FH responses can promote autoimmunity and other pathologies. It is unfortunate that no clinical interventions exist for the selective depletion of follicular T cells to alleviate these diseases. We engineered a chimeric antigen receptor (CAR) facilitating the specific targeting of cells with high expression levels of human programmed cell death protein 1 (PD-1), a cardinal feature of follicular T cells. CAR-expressing human natural killer (NK) cells robustly and discriminately eliminated PD-1 high follicular human T cells in vitro and in a humanized mouse model of lupus-like disease while sparing B cells and other PD-1 low T cell subsets, including regulatory T cells. These results establish a strategy for specific targeting of PD-1 high T cells that can be advanced as a clinical tool for the selective depletion of pathogenic follicular T cells or other PD-1 high target cells in certain disease states.

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