rpr-109881a and Neutropenia

This review describes the experimental and clinical properties of new taxanes and epothilones. Six new taxanes are currently in clinical trials: BMS 184476, BMS 188797, BMS 275183, IDN 5109/BAY 598862, RPR 109881A et RPR 116258 All these derivatives share the same feature which is a decreased recognition by Pgp-170, the product of the MDR1 gene. This confers innovative properties such as in vitro and in vivo activities on tumors expressing the Pgp-170, activity by the oral route. Identification of other families of molecules bearing the same mechanism of action as taxol has been a goal pursued by many groups. The discovery of epothilones led to the pharmaceutical development of two molecules: EPO 906 (which corresponds to the natural compound epothilone B) and BMS 247550. Phase I clinical trials have established that all these investigational drugs (taxanes and epothilones) can be safely administered in patients, the limiting toxicity being most of the time febrile neutropenia. Many tumor responses have been noted.

Topics: Animals; Antineoplastic Agents, Phytogenic; Bridged-Ring Compounds; Clinical Trials, Phase I as Topic; Drug Screening Assays, Antitumor; Humans; Mice; Neutropenia; Paclitaxel; Taxoids

Larotaxel (XRP9881, RPR109881), a novel semi-synthetic taxoid that shares a mode of action with the taxanes docetaxel and paclitaxel, was active in preclinical studies against a broad spectrum of tumour cells and tumour models refractory/resistant to taxanes, and have demonstrated clinical activity in taxane pre-treated/resistant metastatic breast cancer (MBC) patients. The current phase I dose-escalation study sought to define in Japanese patients with advanced solid tumours the maximum tolerated dose (MTD) and recommended dose (RD) of larotaxel administered as a 1-h intravenous infusion every 3 weeks. Eighteen patients were treated in total with 11 of those (61%) having previously received a docetaxel- or paclitaxel-based regimen. The MTD was defined as 90 mg/m(2) following the occurrence of dose-limiting toxicities (DLTs) in two of five patients treated at this dose level including grade 4 neutropenia lasting >7 days or febrile neutropenia. The RD for phase II was consequently 75 mg/m(2) q3w, with no DLTs in the six patients treated. The principal toxicity and DLT was neutropenia, with or without neutropenic complications. Partial responses were reported for 2 of 18 (11%) treated patients and a further 8 achieved stable disease (44%). The clearance 19.1-31.9 L/h was similar to that observed in Caucasian subjects with value of 33.0 +/- 10.7 L/h. In conclusion, larotaxel 75 mg/m(2), administered as a 1-h infusion every 3 weeks, appeared to be clinically tolerable in this Japanese patient population and showed early indications of activity.

Topics: Adult; Aged; Antineoplastic Agents; Asian People; Dose-Response Relationship, Drug; Female; Fever; Humans; Infusions, Intravenous; Japan; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Neutropenia; Taxoids; Treatment Outcome