- Female patients must not be pregnant or breastfeeding; the effects of BMS-247550 on pregnant women and on fetuses are unknown; however, the known toxicities, which include neutropenia, are likely to place pregnant women at increased risk; the mechanism of action of this compound, stabilization of microtubules in dividing cells, is highly likely to be teratogenic; taxanes, which have a similar mechanism of action, are known to be teratogenic NOTE: A negative serum pregnancy test is required =< 2 weeks of randomization for women of childbearing potential