Fibroblast drug scavenging increases intratumoural gemcitabine accumulation in murine pancreas cancer.

OBJECTIVE: Desmoplasia and hypovascularity are thought to impede drug delivery in pancreatic ductal adenocarcinoma (PDAC). However, stromal depletion approaches have failed to show clinical responses in patients. Here, we aimed to revisit the role of the tumour microenvironment as a physical barrier for gemcitabine delivery. DESIGN: Gemcitabine metabolites were analysed in LSL-KrasG12D/+ ; LSL-Trp53R172H/+ ; Pdx-1-Cre (KPC) murine tumours and matched liver metastases, primary tumour cell lines, cancer-associated fibroblasts (CAFs) and pancreatic stellate cells (PSCs) by liquid chromatography-mass spectrometry/mass spectrometry. Functional and preclinical experiments, as well as expression analysis of stromal markers and gemcitabine metabolism pathways were performed in murine and human specimen to investigate the preclinical implications and the mechanism of gemcitabine accumulation. RESULTS: Gemcitabine accumulation was significantly enhanced in fibroblast-rich tumours compared with liver metastases and normal liver. In vitro, significantly increased concentrations of activated 2',2'-difluorodeoxycytidine-5'-triphosphate (dFdCTP) and greatly reduced amounts of the inactive gemcitabine metabolite 2',2'-difluorodeoxyuridine were detected in PSCs and CAFs. Mechanistically, key metabolic enzymes involved in gemcitabine inactivation such as hydrolytic cytosolic 5'-nucleotidases (Nt5c1A, Nt5c3) were expressed at low levels in CAFs in vitro and in vivo, and recombinant expression of Nt5c1A resulted in decreased intracellular dFdCTP concentrations in vitro. Moreover, gemcitabine treatment in KPC mice reduced the number of liver metastases by >50%. CONCLUSIONS: Our findings suggest that fibroblast drug scavenging may contribute to the clinical failure of gemcitabine in desmoplastic PDAC. Metabolic targeting of CAFs may thus be a promising strategy to enhance the antiproliferative effects of gemcitabine.

Central nervous system involvement in children with sarcoma.

OBJECTIVES: To summarize and analyze the experience in CNS involvement (CNSI) in children with sarcomas treated in the above-mentioned institutions. PATIENTS AND METHODS: From 1990 to 2001, all medical charts were retrospectively reviewed: 19 sarcoma patients (12 boys and 7 girls) were diagnosed with CNSI (4 osteogenic sarcomas, 11 Ewing sarcomas, 2 rhabdomyosarcomas, 1 alveolar soft part sarcoma and 1 mesenchymal chondrosarcoma). Mean age of all patients at the time of initial diagnosis was 14.9 years (range: 4-24 years), mean age at the time when CNSI was diagnosed was 16.9 years (range: 5.5-27 years). RESULTS: The frequency of CNSI among our patients was 6.17%. The following symptoms and signs (sometimes combined) presented: headache (10 patients), nausea and vomiting (6 patients), seizures (11 patients) and focal neurological signs (9 patients). The mean duration of time elapsed since diagnosis of CNSI till death or last follow-up was 5.2 months (SD: +/-5.7 months). Four patients received chemotherapy (CT) alone, 8 CT and radiotherapy (RT), 2 RT alone, 3 supportive treatment only, 1 CT and surgery and 1 surgery alone. Sixteen patients died; there was no significant difference in the duration of survival between those who were treated with RT or surgery (mean +/- SD: 6.77 +/- 6.56 months) and those who received only CT or supportive treatment (mean +/- SD: 2.60 +/- 2.94 months) (p = 0.07). Brain disease was the main cause of death in all but 1 patient who died 4 days after autologous bone marrow transplantation from uncontrolled sepsis. In 16 patients, CNSI was part of a metastatic disease. CONCLUSIONS: Among children with sarcoma, CNSI is encountered in 6.17% of cases. More effective therapy has to be developed in order to improve their outcome.