Neutropenia, the principal toxicity, has been dose-limiting in all schedules evaluated to date. On the most extensively studied. Neutropenia is not cumulative and the ANC nadirs are similar with repetitive dosing, suggesting that paclitaxel is not irreversibly toxic to hematopoietic stem cells. The principle predisposing factor for neutropenia is the extent of prior myelotoxic therapy. Another possible predisposing factor may be the infusion schedule.
Sensory neuropathy is the most common neurotoxic effect.
The neurotoxicity is typically cumulative, with symptoms progressing after each treatment at both high and low doses. Motor and autonomic effects have also been reported. The most common cardiac toxicity is a transient asymptomatic bradycardia. Altered function of the enzyme eventually leads to tumor cell death. This approval re-emphasizes the importance of natural products and their derivatives in the search for better cancer treatments.