Cell cycle phase perturbations and apoptosis in tumour cells induced by aplidine

Aplidine, dehydrodidemnin B, is a marine depsipeptide isolated from the Mediterranean tunicate Aplidium albicans currently in phase II clinical trial. In human Molt-4 leukaemia cells Aplidine was found to be cytotoxic at nanomolar concentrations and to induce both a G1 arrest and a G2 blockade. The drug-induced cell cycle perturbations and subsequent cell death do not appear to be related to macromolecular synthesis (protein, RNA, DNA) since the effects occur at concentrations (e.g. 10 nM) in which macromolecule synthesis was not markedly affected. Ten nM Aplidine for 1 h inhibited ornithine decarboxylase activity, with a subsequently strong decrease in putrescine levels. This finding has questionable relevance since addition of putrescine did not significantly reduce the cell cycle perturbations or the cytotoxicity of Aplidine. The cell cycle perturbations caused by Aplidine were also not due to an effect on the cyclin-dependent kinases. Although the mechanism of action of Aplidine is still unclear, the cell cycle phase perturbations and the rapid induction of apoptosis in Molt-4 cells appear to be due to a mechanism different from that of known anticancer drugs

Spisulosine (ES-285) given as a weekly three-hour intravenous infusion: results of a phase I dose-escalating study in patients with advanced solid malignancies

Spisulosine is a marine compound that showed antitumor activity in preclinical studies. We report results of a phase I trial performed in patients with advanced solid tumors with the marine compound, with the aim to determine the maximum tolerated dose (MTD) of a weekly 3-h intravenous (iv.) infusion, and to evaluate the safety, efficacy, and pharmacokinetics (PK) of the compound. Two centers contributed 25 patients to the trial, and 7 dose levels were explored. In dose levels ranging from 4 to 128 mg/mA(2)/day, no dose-limiting toxicities (DLT) were observed. One patient had DLT at 200 mg/mA(2), a reversible grade 3 ALT increase. The MTD was not reached due to early termination of the Spisulosine trial program but is considered to be likely in the range of 200 mg/mA(2) for this schedule. Drug-related adverse reactions included mild to moderate nausea, pyrexia, injection site reactions, and vomiting. One case of grade 4 peripheral motor and sensory neuropathy associated with general weakness and pain was observed during treatment cycle 4 and possibly contributed to the death of the patient. Grade 3 laboratory abnormalities included anemia and lymphopenia and increases in liver enzymes (alkaline phosphatase, transaminases, and bilirubin). Objective responses were not observed, and only four patients had short-lasting stable disease (< 3 months). The PK data indicated a wide distribution, a long residence time, and dose proportionality of the agent. Hepato- and neuro-toxicity are schedule independent dose-limiting adverse events for this marine compound, as illustrated by this and other early clinical trials