Phase I clinical study of the novel epothilone B analogue BMS-310705 given on a weekly schedule

BMS-310705, a water-soluble semi-synthetic analogue of epothilone B, was selected for clinical development because of its in vivo anti-tumour activity and toxicity profile similar to that of ixabepilone, currently the most extensively evaluated and promising epothilone B analogue. The improved solubility of BMS-310705 allowed a cremophore-free formulation that avoided the need for pre-medication.

Two schedules were tested, one with drug administrations on days (D) 1, 8 and 15 followed by 1-week's rest, the other with administrations on D1 and 8 (D1&8 schedule) followed by 1-week's rest. Treatment was given as a 15-min infusion without pre-medication against hypersensitivity. The plasma pharmacokinetics of BMS-310705 was studied in 30 patients. An accelerated titration design 2B was applied for dose escalations. Twenty-seven patients were accrued in the D1, 8, 15 and 32 in the D1&8 schedule.

The dose was escalated from 5-30 mg/m(2)/week with diarrhoea as dose-limiting toxicity; 15 and 20 mg/m(2) were the recommended doses in the D1, 8, 15 and D1&8 schedule, respectively. Other frequent non-haematological toxicities were neurotoxicity, mainly paraesthesia, asthenia and myalgia. Preliminary results showed linear pharmacokinetics along the range of doses tested with a short half-life. Five objective responses were reported.

Further clinical development of BMS-310705 might be worthwhile in solid tumours where ixabepilone or other epothilones are not indicated.