Cellular Uptake Of Gemcitabine Research Articles

Nano-delivery of Gemcitabine Derivative as a Therapeutic Strategy in a Desmoplastic KRAS Mutant Pancreatic Cancer.

Pancreatic ductal adenocarcinoma remains one of the challenging malignancies to treat, and chemotherapy is the primary treatment strategy available to most patients. Gemcitabine, one of the oldest chemotherapeutic drugs approved for pancreatic cancer, has limited efficacy, due to low drug distribution to the tumor and chemoresistance following therapy. In this study, we delivered gemcitabine monophosphate using lipid calcium phosphate nanoparticles, to desmoplastic pancreatic tumors. Monophosphorylation is a critical, rate-limiting step following cellular uptake of gemcitabine and precursor of the pharmacologically active gemcitabine triphosphate. Our drug delivery strategy enabled us to achieve robust tumor regression with a low parenteral dose in a clinically relevant, KRAS mutant, syngeneic orthotopic allograft, lentivirus-transfected KPC cell line-derived model of pancreatic cancer. Treatment with gemcitabine monophosphate significantly increased apoptosis of cancer cells, enabled reduction in the proportion of immunosuppressive tumor-associated macrophages and myeloid-derived suppressor cells, and did not increase expression of cancer stem cell markers. Overall, we could trigger a strong antitumor response in a treatment refractory PDAC model, while bypassing critical hallmarks of gemcitabine chemoresistance.

The association of epithelial expression of hENT1 and survival from adjuvant gemcitabine in pancreatic ductal adenocarcinoma (PDAC).

296 Background: Human equilibrative nucleoside transporter 1 (hENT1) mediates the cellular uptake of gemcitabine. Low tumour hENT1 expression has been associated with reduced survival from gemcitabine in some studies. We analyzed the prognostic effect of hENT1 expression in a cohort of PDAC patients (pts) who underwent surgical resection. Methods: A tissue microarray (TMA) composed of duplicate 0.6 mm cores from 261 resected PDACs was constructed from all available cases derived from the archives of Vancouver General Hospital between 1988 - 2013. TMA sections (4 µm) were stained with an antibody for hENT1 (SP120- Spring Biosciences) and scored using a four-tiered scoring system (negative, weak, moderate and strong staining). The expression of hENT1 in the epithelial component of PDAC was quantified and patient samples were divided into low (negative and weak staining) and high (moderate and strong staining) hENT1-expressing groups. Treatment and survival data were collected. Survival differences were quantified with Kaplan-Meier method and log-rank statistic. Results: Our cohort included pts who received no adjuvant chemotherapy (CT) (n=182) or gemcitabine (n=59). Cases treated with other regimens (n=20) were excluded. There was no significant difference in the median overall survival (OS) between pts with low (14.0 months, n=167) and high hENT1 expression (15.2 months, n=15) in the absence of adjuvant CT. Gemcitabine treated patients with low hENT1 expression (n=51) had a median OS of 20.9 months. Median OS was not reached in the group of pts with high hENT1 expression (n=8) who received gemcitabine, with only 2 deaths at the 24 month time point and 6 censorings (p = 0.045). Pts who received gemcitabine had an increased median OS (24.8 months) compared to pts who did not receive adjuvant CT (14.0 months) regardless of hENT1 expression (p<0.0001). Conclusions: Consistent with the ESPAC-3 data, in our analysis adjuvant gemcitabine was associated with increased OS in PDAC pts with high epithelial hENT1 expression (determined using the SP120 antibody) compared to pts with low hENT1 expression. Prospective evaluation of the predictive value of hENT1 expression in this setting is needed.

Surface-modified gemcitabine with mucoadhesive polymer for oral delivery†

Gemcitabine microparticles were prepared using chitosan, polyethylene oxide or carbopol as the mucoadhesive polymer and eudragit L100-55 as the enteric polymer by a double emulsion method. The particle size and zeta potential changed from 1338.3 ± 254.1 nm to 2459.4 ± 103.6 nm and −5.16 ± 1.62 mV to 2.84 ± 0.65 mV, respectively, with increasing chitosan to gemcitabine weight ratio from 0.25 to 1. The gemcitabine-loaded microparticles without mucoadhesive polymer (F50) showed the particle size and zeta potential of 671.3 ± 58.3 nm and − 16.7 ± 1.82 mV, respectively. The cellular uptake of gemcitabine into Caco-2 cells from gemcitabine-loaded microparticles with chitosan increased with increasing incubation time in Caco-2 cells compared to that of gemcitabine-loaded microparticles with polyethylene oxide or carbopol, suggesting that chitosan might be the optimal mucoadhesive polymer. Gemcitabine microparticles will be tested to identify whether the oral absorption could be increased in the future.