title: Irinophore C™, a lipid nanoparticulate formulation of irinotecan, improves vascular function, increases the delivery of sequentially administered 5-FU in HT-29 tumors, and controls tumor growth in patient derived xenografts of colon cancer.
abstract: OBJECTIVE
  A liposomal formulation of irinotecan, Irinophore C™ (IrC™) is efficacious in a panel of tumor models, normalizes tumor vasculature, and increases the accumulation of a second drug in the same tumor. We now show that Irinophore C™ is also effective against patient derived xenografts (PDX) of colon cancer, and examine the kinetics of vascular normalization in the HT-29 tumor model and assess how these changes might be used with 5-FU sequentially.
  
  
  METHODS
  Rag2M mice bearing HT-29 tumors were treated with IrC™ (25mg/kg; Q7D×3) for up to three weeks. Groups of tumors were harvested for analysis at 7, 14 and 21days after the start of treatment. Drug and lipid levels in the tumor were evaluated using HPLC and scintillation counts, respectively. Changes in tumor morphology (H&E), vasculature (CD31), perfusion (Hoechst 33342) and apoptosis (TUNEL) were quantified using microscopy. The accumulation of a second drug ([(14)C]-5-FU, 40mg/kg) given 3h before sacrifice was determined using liquid scintillation. The efficacy of IrC™ (Q7D×3) followed by 5-FU treatment (Q7D×3) was assessed in mice bearing established HT-29 tumors. The efficacy of IrC™ was also evaluated in primary human colorectal tumors grown orthotopically in NOD-SCID mice.
  
  
  RESULTS
  Following a single dose of IrC™ the active lactone forms of irinotecan and its metabolite SN-38 were measurable in HT-29 tumors after 7days. The treatment reduced tumor cell density and increased apoptosis. Hoechst 33342 perfusion and accumulation of [(14)C]-5-FU in the treated tumors increased significantly on days 7 and 14. This was accompanied by an increase in the number of endothelial cells relative to total nuclei in the tumor sections. Pre-treatment with IrC™ (Q7D×3) followed by 5-FU (Q7D×3) delayed the time taken for tumors to reach 1cm(3) by 9days (p<0.05). IrC™ was just as effective as free irinotecan when used on patient derived xenografts of colorectal cancer.
  
  
  CONCLUSIONS
  Treatment with IrC™ reduces tumor cell viability and appears to normalize the vascular function of the tumor after a single treatment cycle. A concomitant increase in the accumulation of a second drug (5-FU) in the tumor was observed in tumors from IrC™ treated animals and this was correlated with changes in vascular structure consistent with normalization. The treatment effects of sequential 5-FU dosing following IrC™ are additive with no additional toxicity in contrast to previous studies where concurrent 5-FU and IrC™ treatment exacerbated 5-FU toxicity. The studies with PDX tumors also indicate that IrC™ is just as effective as free irinotecan on PDX tumors even though the delivered dose is halved.
authors.affiliation: Department of Pharmacy, University Medical Centre Utrecht, Postbus 85500, 3508 GA Utrecht, The Netherlands; Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada. Electronic address: robertneijzen@gmail.com.
authors.forename: Robert
authors.initials: R
authors.lastname: Neijzen
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: May Q
authors.initials: MQ
authors.lastname: Wong
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: Navdeep
authors.initials: N
authors.lastname: Gill
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: He
authors.initials: H
authors.lastname: Wang
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: Tamanna
authors.initials: T
authors.lastname: Karim
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: Malathi
authors.initials: M
authors.lastname: Anantha
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: Dita
authors.initials: D
authors.lastname: Strutt
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada.
authors.forename: Dawn
authors.initials: D
authors.lastname: Waterhouse
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada; The Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada; The Centre for Drug Research and Development, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Marcel B
authors.initials: MB
authors.lastname: Bally
authors.affiliation: Michael Smith Genome Sciences Centre, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC, Canada; Division of Gastroenterology, Department of Medicine, University of British Columbia, University of British Columbia, Vancouver, BC V6T 2B5, Canada.
authors.forename: Isabella T
authors.initials: IT
authors.lastname: Tai
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada; The Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Sylvia S W
authors.initials: SS
authors.lastname: Ng
authors.affiliation: Experimental Therapeutics, The British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada; The Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada. Electronic address: dyapp@bccrc.ca.
authors.forename: Donald T
authors.initials: DT
authors.lastname: Yapp
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology*; D001808:Blood Vessels / Q000187:drug effects; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D002626:Chemistry, Pharmaceutical; D003110:Colonic Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D016503:Drug Delivery Systems; D005472:Fluorouracil / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D049329:Nanostructures; D012039:Regional Blood Flow / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000964:Antimetabolites, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D005472:Fluorouracil; D002166:Camptothecin
keywords: Colorectal cancer; HT-29 tumors; Irinotecan; Liposomes; Patient derived xenografts; Sequential therapy