title: Methotrexate-conjugated PEGylated dendrimers show differential patterns of deposition and activity in tumor-burdened lymph nodes after intravenous and subcutaneous administration in rats.
abstract: The current study sought to explore whether the subcutaneous administration of lymph targeted dendrimers, conjugated with a model chemotherapeutic (methotrexate, MTX), was able to enhance anticancer activity against lymph node metastases. The lymphatic pharmacokinetics and antitumor activity of PEGylated polylysine dendrimers conjugated to MTX [D-MTX(OH)] via a tumor-labile hexapeptide linker was examined in rats and compared to a similar system where MTX was α-carboxyl O-tert-butylated [D-MTX(OtBu)]. The latter has previously been shown to exhibit longer plasma circulation times. D-MTX(OtBu) was well absorbed from the subcutaneous injection site via the lymph, and 3 to 4%/g of the dose was retained by sentinel lymph nodes. In contrast, D-MTX(OH) showed limited absorption from the subcutaneous injection site, but absorption was almost exclusively via the lymph. The retention of D-MTX(OH) by sentinel lymph nodes was also significantly elevated (approximately 30% dose/g). MTX alone was not absorbed into the lymph. All dendrimers displayed lower lymph node targeting after intravenous administration. Despite significant differences in the lymph node retention of D-MTX(OH) and D-MTX(OtBu) after subcutaneous and intravenous administration, the growth of lymph node metastases was similarly inhibited. In contrast, the administration of MTX alone did not significantly reduce lymph node tumor growth. Subcutaneous administration of drug-conjugated dendrimers therefore provides an opportunity to improve drug deposition in downstream tumor-burdened lymph nodes. In this case, however, increased lymph node biodistribution did not correlate well with antitumor activity, possibly suggesting constrained drug release at the site of action.
authors.affiliation: Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria, Australia , 3052.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Kaminskas
authors.forename: Victoria M
authors.initials: VM
authors.lastname: McLeod
authors.forename: David B
authors.initials: DB
authors.lastname: Ascher
authors.forename: Gemma M
authors.initials: GM
authors.lastname: Ryan
authors.forename: Seth
authors.initials: S
authors.lastname: Jones
authors.forename: John M
authors.initials: JM
authors.lastname: Haynes
authors.forename: Natalie L
authors.initials: NL
authors.lastname: Trevaskis
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Chan
authors.forename: Erica K
authors.initials: EK
authors.lastname: Sloan
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Finnin
authors.forename: Mark
authors.initials: M
authors.lastname: Williamson
authors.forename: Tony
authors.initials: T
authors.lastname: Velkov
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Williams
authors.forename: Brian D
authors.initials: BD
authors.lastname: Kelly
authors.forename: David J
authors.initials: DJ
authors.lastname: Owen
authors.forename: Christopher J H
authors.initials: CJ
authors.lastname: Porter
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D050091:Dendrimers / Q000737:chemistry* / Q000493:pharmacokinetics*; D005260:Female; D005434:Flow Cytometry; D008198:Lymph Nodes / Q000378:metabolism*; D008297:Male; D008727:Methotrexate / Q000737:chemistry* / Q000493:pharmacokinetics*; D018613:Microscopy, Confocal; D009369:Neoplasms / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry*; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley
chemical_list: D050091:Dendrimers; D011092:Polyethylene Glycols; D008727:Methotrexate
keywords: dendrimer; lymphatic; lymphatic metastasis; methotrexate; pharmacokinetics; subcutaneous