Lipophilic cisplatin analogues entrapped in liposomes

Role of intraliposomal drug activation in biological activity

Roman Perez-Soler, Abdul R. Khokhar

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

cis-Bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) (NDDP), a lipophilic cisplatin analogue containing two branched leaving groups of 10 carbon atoms, is undergoing clinical evaluation in a liposomal formulation. In previous studies, NDDP entrapped in multilamellar vesicles composed of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylglycerol (DMPG) at a 7:3 molar ratio was non-nephrotoxic in humans, not cross-resistant with cisplatin in different in vitro and in vivo systems, and more active than cisplatin against murine models of experimental liver metastases whereas free NDDP was devoid of in vivo antitumor activity at the optimal dose of L-NDDP and barely active at higher doses. To elucidate the mechanisms by which the liposomal carrier enhances the biological properties to this class of antitumor agents, we studied the effect of the liposome composition, size of the branched leaving groups of the platinum compound, and pH and composition of the aqueous phase on the entrapment efficiency, drug leakage, drug stability, and in vivo toxicity and antitunor activity of different liposomal formulations of these agents. In experiments using normal saline as aqueous phase, the presence of DMPG in the lipid bilayer resulted in a decreased stability and an increased biological activity of NDDP, whereas NDDP entrapped in liposomes composed of DMPC alone (not containing DMPG) was stable but devoid of antitumor activity. In studies with structurally related analogues with branched leaving groups of 5, 6, 7, and 9 carbon atoms, similar trends were observed. In addition, the number of carbon atoms in the leaving groups was directly and inversely related to the entrapment efficiency and stability of the analogues, respectively, independently of lipid composition; increasing the size of the branched leaving groups resulted in an increased in situ degradation of the platinum compound and enhanced biological activity and potency. These results suggest that this class of platinum compounds exerts its biological activity through the formation of active intermediates in situ within the lipid bilayers and that the activation reaction is highly dependent on the presence of DMPG and the size of the lipophilic leaving group.

Original languageEnglish (US)
Pages (from-to)6341-6347
Number of pages7
JournalCancer Research
Volume52
Issue number22
StatePublished - Nov 15 1992
Externally publishedYes

Fingerprint

Platinum Compounds
Liposomes
Cisplatin
Dimyristoylphosphatidylcholine
Carbon
Lipid Bilayers
Drug Stability
Antineoplastic Agents
Theoretical Models
Neoplasm Metastasis
Lipids
Metabolic Activation
dimyristoylphosphatidylglycerol
Liver
Pharmaceutical Preparations

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Lipophilic cisplatin analogues entrapped in liposomes : Role of intraliposomal drug activation in biological activity. / Perez-Soler, Roman; Khokhar, Abdul R.

In: Cancer Research, Vol. 52, No. 22, 15.11.1992, p. 6341-6347.

Research output: Contribution to journalArticle

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