A phase I, dose escalation trial of ZD0473, a novel platinum analogue, in combination with gemcitabine

Picoplatin pharmacokinetics and chemotherapy of non-small cell lung cancer

INTRODUCTION

Picoplatin was developed as platinum coordination complex to overcome development of resistance, through conjugation to thioles, by the introduction of a methyl-pyridine moiety into the cisplatin parent structure. Pharmacokinetic parameters of the drug, after intravenous and oral application, were studied in solid tumors and clinical Phase I - III trials performed, in particular in NSCLC and small cell lung cancer (SCLC). Results showed low clinical activity of picoplatin.

AREAS COVERED

This article presents an overview of the pharmacokinetic assessments of picoplatin in lung cancer. Specifically, the authors address the relationship between disposition and clinical activity of the drug.

EXPERT OPINION

Picoplatin failed to overcome resistance to platinum compounds in lung cancer to achieve significant improved survival of most patients. Even highest doses of the drug reaching 150 m/m² given intravenously every 3 weeks were not sufficient to achieve better response than existing chemotherapeutics and the oral bioavailability of a dose of 200 - 400 mg corresponded only to 80 mg/m² iv. Picoplatin therefore seem to be quite ineffective. Picoplatin is expected to overcome tumor resistance in cases which overexpress thiol-conjugating pathways; however, this was not proved in clinical trials. To conclude, this blocked platinum complex is not able to reverse cisplatin resistance to a significant extent in vivo and its mechanisms and kinetics and of DNA damage failed to produce significant clinical results compared to second-line standard therapy for lung cancer.

Platinum anticancer drugs. From serendipity to rational design

The discovery of cis-platin was serendipitous. In 1965, Rosenberg was looking into the effects of an electric field on the growth of Escherichia coli bacteria. He noticed that bacteria ceased to divide when placed in an electric field but what Rosenberg also observed was a 300-fold increase in the size of the bacteria. He attributed this to the fact that somehow the platinum-conducting plates were inducing cell growth but inhibiting cell division. It was later deduced that the platinum species responsible for this was cis-platin. Rosenberg hypothesized that if cis-platin could inhibit bacterial cell division it could also stop tumor cell growth. This conjecture has proven correct and has led to the introduction of cis-platin in cancer therapy. Indeed, in 1978, six years after clinical trials conducted by the NCI and Bristol-Myers-Squibb, the U.S. Food and Drug Administration (FDA) approved cis-platin under the name of Platinol(®) for treating patients with metastatic testicular or ovarian cancer in combination with other drugs but also for treating bladder cancer. Bristol-Myers Squibb also licensed carboplatin, a second-generation platinum drug with fewer side effects, in 1979. Carboplatin entered the U.S. market as Paraplatin(®) in 1989 for initial treatment of advanced ovarian cancer in established combination with other approved chemotherapeutic agents. Numerous platin derivatives have been further developed with more or less success and the third derivative to be approved in 1994 was oxaliplatin under the name of Eloxatin(®). It was the first platin-based drug to be active against metastatic colorectal cancer in combination with fluorouracil and folinic acid. The two others platin-based drugs to be approved were nedaplatin (Aqupla(®)) in Japan and lobaplatin in China, respectively. More recently, a strategy to overcome resistance due to interaction with thiol-containing molecules led to the synthesis of picoplatin in which one of the amines linked to Pt was replaced by a bulky methyl substituted pyridine allowing the drug more time to reach its target, DNA. On the other hand, efforts which were made to find new orally administered analog led to satraplatin bearing to axial acetate groups. Both drugs are still under clinical trials. An alternatively route to the discovery of new derivatives turns to the development of improved delivery strategies such as liposomes and polymers. Liposomal cis-platin or lipoplatin in under a phase III randomized clinical trial for patients suffering from small cell lung cancer whereas polymer-based drug, Prolindac™ is currently under investigation for pretreated ovarian cancers in up to eight European centers.

New-generation platinum agents for solid tumors

Cisplatin was one of the first chemotherapeutic agents to exhibit broad efficacy in solid tumors and it remains among the most widely used agents in the treatment of cancer. Its introduction inspired great efforts to design similarly effective platinum agents that overcome the three main limitations of cisplatin: toxicity, tumor resistance and poor oral bioavailability. However, 40 years after the initial discovery of cisplatin, only two platinum agents have garnered US FDA approval: carboplatin and oxaliplatin. Although hundreds of promising agents were tested in clinical trials during the 1990s, only oxaliplatin made it past clinical development. For a brief period, the economic cost of these unsuccessful efforts retarded further efforts to develop new agents. However, two exciting platinum agents have been brought to Phase III trials: satraplatin in hormone-refractory prostate cancer and picoplatin in small-cell lung cancer. If successful, they may inspire a new effort to bring better-designed platinum agents to market. This article reviews the clinical development of platinum agents to date and speculates on the role of platinum agents in the near future.

Broadening the clinical use of platinum drug-based chemotherapy with new analogues. Satraplatin and picoplatin

The three platinum-containing drugs that have been thus far approved by the FDA - cisplatin, carboplatin and oxaliplatin - have had a significant effect in the treatment of patients with some malignancies such as testicular, ovarian and colorectal cancer. However, much more remains to be achieved to widen the therapeutic use of this important class of drug, either via further analogue development or by judicious use of combining the existing drugs with new molecularly targeted agents. Two analogues arising from an academic (Institute of Cancer Research)/pharmaceutical (Johnson Matthey/AnorMed) collaboration - satraplatin (JM-216) and picoplatin (JM-/AMD-473) - have recently shown promising clinical activity; satraplatin (an orally available drug) in hormone-refractory prostate cancer and picoplatin in small-cell lung cancer. There have also been advances in delivery vehicles for platinum drugs (e.g., the diaminocyclohexane [DACH]-based AP-5346 and aroplatin/liposomal cis-bis-neodecanoato-trans-(R,R)-1,2-diaminocyclohexane platinum (II) [L-NDDP] are in early clinical development). Platinum-based drugs have also been successfully combined with molecularly targeted drugs (e.g., the recent approval of the vascular endothelial growth factor monoclonal antibody bevacizumab with carboplatin and paclitaxel in patients with NSCLC).

Synthesis and characterization of palladium(II) and platinum(II) complexes with Schiff bases derivatives of 2-pyridincarboxyaldehyde. Study of their interaction with DNA

Several Schiff bases ligand derivatives of 2-pyridincarboxyaldehyde and different amines, together with their palladium(II) and platinum(II) complexes have been synthesised and characterised. The aim of this study is to probe the influence of substituents beared on the pyridyl/toulene ring at different position to their possible antitumor activity. The amines used were o-, m-, p-toluidine and 4-hydroxyaniline. All the compounds were characterised by elemental analysis, FT-IR spectroscopy, 1H and 195Pt NMR spectroscopy and matrix assisted laser desorption/ionization time-of-flight mass spectroscopy. The formation of DNA adducts were analysed by circular dichroism and electrophoretic mobility. Atomic force microscopy images of the compounds with plasmid DNA pBR322 were also obtained. In all cases changes in the second and tertiary structure of DNA could be observed as a consequence of the covalent interaction of the palladium(II) or platinum(II) ions with the N of the nucleobases. However, there are not significant differences in the behavior of the complexes related to the position of the methyl groups or the presence of the OH group. Values of IC50 were also calculated for the platinum(II) complexes for several pairs of ovarian tumor cell lines which were either sensitive or resistant to cisplatin. Finally in vitro apoptosis studies for platinum(II) complexes with ovarian tumor cell lines A2780/A2780cisR were carried out. The results indicated interesting antiproliferative activity and significant apoptosis induction.

Safety profile of platinum-based chemotherapy in the treatment of advanced non-small cell lung cancer in elderly patients

Non-small cell lung cancer (NSCLC) may be considered typical of advanced age. More than 50% of NSCLC patients are diagnosed at > 65 years of age and approximately one-third of all patients are > 70 years of age. Elderly patients tolerate chemotherapy poorly compared with their younger counterpart because of the progressive reduction of organ function and comorbidities related to age. For this reason, these patients are often not considered eligible for aggressive platinum-based chemotherapy, the standard medical treatment for advanced NSCLC. In clinical practice, single-agent chemotherapy should remain the standard treatment. Feasibility of platinum-based chemotherapy remains an open issue and has to be proven prospectively. Moreover, a multidimensional geriatric assessment for individualised treatment choice in NSCLC elderly patients is mandatory. This review focuses on the currently-available evidences for the treatment of elderly patients affected by advanced NSCLC with regards to the role and safety of platinum-based chemotherapy.

New-generation platinum drugs in the treatment of cisplatin-resistant cancers

Platinum drugs with altered stable ligands, such as oxaliplatin and satraplatin, produce a different DNA-adduct profile to cisplatin. This results in a distinct therapeutic profile, and clinical trials with these agents demonstrate significant anticancer activity in diseases with inherent or acquired resistance to cisplatin, such as colorectal and prostate cancers as well as previously treated ovarian and germ-cell cancer. An alternative approach to increasing the efficacy associated with platinum therapy is to enhance tumour delivery by coupling platinum drugs with a polymer or encapsulating the agent in a liposome. The early clinical trials of these novel delivery formulations are promising but, as yet, have not confirmed that the delivery of platinum to the tumour cell DNA is increased.