Abstract A118: Efflux of paclitaxel nanoformulation in cell culture model of human placental barrier

Background: Breast cancer affects 1 of every 3000 pregnancies, and is treated with chemotherapeutics including paclitaxel. Chemotherapy administration in pregnancy is associated with fetal morbidity. Purpose: Here, we investigated the transplacental transfer of both paclitaxel and new paclitaxel nanoformulations that are entering clinical studies or are commercially available for use in breast cancer. In addition, we examined the transfer of fluorescent albumin-based and polymeric micellar nanoformulations with similar properties to those paclitaxel nanoformulations. Methods: Transport studies were performed using BeWo b30 cells (human placental trophoblast cells) seeded in TranswellTM plates coated with human placental collagen. Cells were treated with 20 μg/mL of paclitaxel from marketed formulations. Since paclitaxel undergoes efflux by P-glycoprotein (P-gp) substrate, 100 μM of verapamil was used as a competitive P-gp inhibitor to prevent efflux of free paclitaxel released from the nanoformulations. In order to determine the role of nanomaterials in transport and uptake of paclitaxel, we synthesized fluorescent albumin nanoparticles and fluorescent polymeric micelles with similar properties to the paclitaxel nanoformulations for use in transport studies. Samples were analyzed by high-performance liquid chromatography or fluorometer. Uptake measurements were corrected for protein content. Particle size and polydispersity index were determined using dynamic light scattering. Results: There were no formulation-dependent differences in paclitaxel permeability between the formulations of paclitaxel, nanoparticle albumin-bound paclitaxel (nab-paclitaxel), and paclitaxel-loaded polymeric micelles. In the presence of verapamil, nab-paclitaxel showed a twofold increase in permeability, in contrast to the other formulations. The size of fluorescent albumin nanoparticles (130.3nm) was matched with nab-Paclitaxel (156.2 nm), and the fluorescent micelles (27.6 nm) with paclitaxel-loaded polymeric micelles (27.7nm). The apparent permeability of the fluorescent albumin nanoparticles across the BeWo cells was 1.98 x 10-6 ± 0.81 x 10-6 cm/s, whereas the apparent permeability of the fluorescent micelles was 59.5 x 10-6 ± 10.5 x 10-6 cm/s. Conclusion: These data suggest that paclitaxel-encapsulated micelles may evade efflux by P-gp and cross the trophoblast to a significant extent, while paclitaxel albumin nanoparticles behave like free paclitaxel. Therefore, choice of formulation may have a significant impact on fetal exposure to paclitaxel. We anticipate that these findings will have an impact on future pharmaceutical design and rational development of safe treatment strategies for pregnancy-associated breast cancer and other diseases. Citation Format: Shariq Ali, Sanaalarab Alenazy, Mansi Shah, Luke Bourner, Erik Rytting. Efflux of paclitaxel nanoformulation in cell culture model of human placental barrier [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A118.