Abstract 1796P
Background
Tumorigenic CTCs express the chemokine receptor CXCR4 and CXCL12 attracts bone marrow cells and CXCR4+ cancer cells at metastatic sites. To isolate and characterize CTCs-CXCR4+ cells a CXCL12-loaded-hydrogel (CLG) using the Belotero® Hyaluronic gel dermal filler was developed. CLG should reproduce a “pseudo niche” attracting and trapping CTCs.
Methods
Human renal cancer (RCC) SN12C/A498, colon cancer (CRC) HT29 and ovarian cancer (OC) OVCAR8 cells migrated through 150μl Empty Gels (EG) or CLG [300 ng/ml CXCL12] and DAPI-stained for enumeration. HT29 cells recovered from EG (HT29-EG) and CLG (HT29-CLG) were assessed for CXCR4 expression, CXCL12-migration, sensitivity to chemotherapeutic drugs, and colonies formation capability. TRAP4MET is a monocentric biological clinical trial (EC n. 50/20) in which 50 metastatic patients will be enrolled to evaluate feasibility of CLG-dependent CTCs isolation and characterization. 7cc blood are Ficoll-paqued and seeded on CLG to identify DAPI+/pan-CK+/CD45- cells and compared to Screen Cell™ isolated CTCs.
Results
A498, SN12C, HT29 and OVCAR8 cells more efficiently infiltrate CLG than EG (CLG/EG fold increase 1.6, 1.9, 1.25 and 2.8 respectively). Compared to HT29 and HT29-EG, HT29-CLG overexpress CXCR4 (21.5±0.3 /18±2.2/ 42.5%±15 respectively) and highly migrates toward CXCL12 (migration index: 2,5/3,1 and 4,3 respectively). Moreover, gel recovered cells, develop higher number of colonies (131±8/176±21 and 171±21 respectively) and are more resistant to 5-FU (IC50 2.7/ 6.5 and 5.6μM respectively) as compared to parental cells. TRAP4MET enrolled 20 patients (8 OC, 4 RCC, 4 Endometrial Cancer (EC), 3 CRC and 1 Lung Cancer (LC). CTCs were successfully isolated from CLG (average CTC/cc 1.93±0.61 in RCC, 1.89±0.56 in OC, 0.61±0.23 in EC and 2.14±0.71 in CRC) and ScreenCell™ (5.42±3.78 in RCC, 1.42±0.35 in OC, 1.67±0.49 in EC and 4.56±2.32 in CRC). CLG-isolated-CTCs number did not correspond to ScreenCell™ suggesting that CLG may select CTCs with different biological features.
Conclusions
CLG is able to isolate and enumerate specific CXCR4+ cancer cells and patient’s CTCs-subpopulation. Molecular characterization of CLG-isolated -cancer cells and -patients’ CTCs is ongoing.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.