The availability of blood-based diagnostic testing using a non-invasive technique holds promise for real-time monitoring of disease progression and treatment selection. Circulating tumor cells (CTCs) have been used as a prognostic biomarker for the metastatic breast cancer (MBC). The molecular characterization of CTCs is fundamental to the phenotypic identification of malignant cells and description of the relevant genetic alterations that may change according to disease progression and therapy resistance. However, the molecular characterization of CTCs remains a challenge because of the rarity and heterogeneity of CTCs and technological difficulties in the enrichment, isolation and molecular characterization of CTCs. In this pilot study, we evaluated circulating tumor associated cells in one blood draw by size exclusion technology and cytological analysis. Among 30 prospectively enrolled MBC patients, CTCs, circulating tumor cell clusters (CTC clusters), CTCs of epithelial–mesenchymal transition (EMT) and cancer associated macrophage-like cells (CAMLs) were detected and analyzed. For molecular characterization of CTCs, size-exclusion method for CTC enrichment was tested in combination with DEPArray™ technology, which allows the recovery of single CTCs or pools of CTCs as a pure CTC sample for mutation analysis. Genomic mutations of TP53 and ESR1 were analyzed by targeted sequencing on isolated 7 CTCs from a patient with MBC. The results of genomic analysis showed heterozygous TP53 R248W mutation from one single CTC and pools of three CTCs, and homozygous TP53 R248W mutation from one single CTC and pools of two CTCs. Wild-type ESR1 was detected in the same isolated CTCs. The results of this study reveal that size-exclusion method can be used to enrich and identify circulating tumor associated cells, and enriched CTCs were characterized for genetic alterations in MBC patients, respectively.

311 Background: Aurora A kinase (AK) phosphorylates and interacts with androgen receptor (AR) and enhances AR DNA binding activity. We hypothesized that AK contributes to castration resistance in PCa, and targeting AK can inhibit AR function and re-sensitize PCa cells to AR signaling inhibitors such as abiraterone. Methods: Aphase I/II, open label, single institution trial to determine the safety and efficacy of AK inhibitor alisertib when given in combination with abiraterone plus prednisone (AP) was planned. Eligible subjects had mCRPC with disease progression on abiraterone. Androgen deprivation plus abiraterone and prednisone were maintained through the trial. Subjects were treated with dose escalation per standard 3+3 design. Planned 3 dose cohorts of alisertib were 30, 40, 50 mg PO BID D 1-7 every 21 D. Correlative studies included kinetics of neuroendocrine tumor markers, enumeration and AK gene amplification of CTCs. Results: Nine of 43 planned subjects were enrolled, 3 in cohort 1 without DLT. Two DLTs developed in cohort 2, thus 3 more patients were enrolled into cohort 1, and 2 developed DLT (total 2/6) in this cohort. The grade 3/4 toxicities (4/9) include neutropenic fever (1/9), neutropenia (1/9), fatigue with memory impairment (1/9), and mucositis (diarrhea and mouth sores, 1/9). Pharmacodynamically, adding alisertib did not affect circulating total testosterone and DHEA levels. Only one patient had decreased Chromogranin A level lasted for 4 months when compared to baseline. Four (4/9) patients had ≥ 5 CTCs at baseline but no conversion ( to < 5) was observed. No PSA decrease was observed during the study. Mean duration of study was 2.5 months. The toxicity / efficacy ratio did not warrant further dose expansion and the trial was terminated early after discussion with sponsor. Conclusions: A tolerable dose of alisertib in combination with AP in mCRPC was not established in this study. There was no clear signal indicating that alisertib might be beneficial for patients with mCRPC progressing on abiraterone. Clinical trial information: NCT01848067.