Abstract 3775: Hydrogel-assisted pathological study of the circulating tumor cells filtered from the renal cell carcinoma patients’ blood

Introduction: Circulating tumor cells (CTCs), defined as tumor cells detached from the primary tumor site and circulating in the peripheral blood, are a promising marker to get the information about tumor status and metastatic potential. However, the limited detection ability as well as their biased specificity of current CTC isolation struggle from understanding the comprehensive characteristics of CTCs. In addition, previous CTC isolation depending on epithelial cell adhesion molecule (EpCAM) antibody make their cytological and pathological study hard. We developed the methods which capture CTCs based on their size and deformability, and construct a hydrogel-assisted cell block for verifying the diagnostic utility for various cancer-associated immuno-markers and their pathological studies. Methods: Two renal cell carcinoma cell lines, SN12C and 769P, and 7 different cancer patients’ blood with renal cell carcinoma were used. To find the applicable markers for diagnosing renal cell carcinoma, we constructed the cell blocks of two cell lines. For the encapsulation of the cells, 4 % alginate was prepared by dissolving in deionized water under constant stirring at 85 °C. Then, the separately prepared renal cancer cells were gently mixed into the dissolved alginate solution. After careful mixing, the solution was loaded into calcium chloride solution drop by drop using volume pipette, followed by 15 min of further incubation with constant stirring. Next, the cell-containing beads were applied to the commonly used procedure for paraffin tissue blocks, and 8 different cancer-associated immuno-markers (EpCAM, CK (AE1/AE3), CAM5.2, EMA, CD10, CA IX, RCC, and vimentin) were stained with each dissected cell blocks. The CTCs from the 7 clinical samples were isolated by tapered-slit filter, and cell containing slides were immunohistochemically stained and examined by pathologist. Results: The four markers, EpCAM, CK (AE1/AE3), CD10, and vimentin in the SN12C cell block were highly expressed. The three markers, CK (AE1/AE3), CD10, and vimentin in the 769-P cell block were predominantly expressed. The EpCAM, CK (AE1/AE3), and CD10 are chosen as the potential immunomarkers for CTC-based diagnosing for RCC. In the clinical study using the 0.5-3.0 ml of blood samples, CTCs were successfully isolated and detected immunohistochemically in 57.1 % (4 of 7) of patients and ranged from 1 to 5. Of 4 CTC positive samples, two had CK (AE1/AE3) positive, each one had EpCAM and CD10 positive CTCs, respectively. Discussion and conclusion: Although the vimentin is highly expressed in both cell blocks, due to diffuse positivity for leukocyte, single use of vimentin for cancer diagnosis is limited. This comprehensive study including immuno-markers screening and their applicability test with clinical samples demonstrates the clinical utility of the present device and hydrogel-assisted cell block for CTC isolation and cancer studies. Citation Format: Yoon-Tae Kang, Young Jun Kim, Tae Hee Lee, Hee Jin Chang, Hyun-Moo Lee, Young-Ho Cho. Hydrogel-assisted pathological study of the circulating tumor cells filtered from the renal cell carcinoma patients’ blood [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3775. doi:10.1158/1538-7445.AM2017-3775