The feasibility of 18F-FES and 18F-FDG microPET/CT for early monitoring the effect of fulvestrant on sensitizing docetaxel by downregulating ERα in ERα+ breast cancer.

OBJECTIVE

Our study aimed to investigate the feasibility of PET/CT for monitoring the influence of fulvestrant on sensitizing docetaxel by downregulating ERα in ERα+ breast cancer.

METHODS

Docetaxel-insensitive ERα+ breast cancer cells (DIS-ZR751) were established, identified and cultured. ERα expression, toxicity and viability of DIS-ZR751 were analyzed before and after treatment in vitro. DIS-ZR751-bearing nude mice were randomly divided into four groups according to different treatments: blank (DIS-ZR751), docetaxel (DIS-ZR751+DOC), fulvestrant (DIS-ZR751+FUL), and combination treatment (DIS-ZR751+DOC+FUL). 18F-FES and 18F-FDG microPECT/CT scans were performed before and 7, 14 days after treatment. Absolute %ID/gmax was calculated.

RESULTS

ERα expression level and growth rate of DIS-ZR751 were higher than control group and decreased dramatically after docetaxel and fulvestrant combination treatment. 18F-FES and 18F-FDG PET/CT imaging in vivo revealed that ERα expression in DIS-ZR751 treated with fulvestrant, and tumor activity in DIS-ZR751 treated with combination drugs decreased as early as 7 days after treatment.

CONCLUSIONS

18F-FES and 18F-FDG PET/CT were feasible for early monitoring the effect of fulvestrant on sensitizing docetaxel by downregulation of ERα in ERα+ breast cancer noninvasively.