A New Option for Metastatic Breast Cancer
Philadelphia, PA—The new biologic therapy eribulin (Halaven) was recently approved by the US Food and Drug Administration for the treatment of patients with metastatic breast cancer. Stephen C. Malamud, MD, Attending Physician, Beth Israel Medical Center, New York City, discussed the benefits and risks associated with this new treatment option at a special session during the meeting.
Eribulin is a nontaxane microtubule dynamics inhibitor indicated for the treatment of metastatic breast cancer in patients who have previously received treatment with at least 2 chemotherapeutic medications that include a taxane and an anthracycline in the adjuvant or metastatic setting.
According to Dr Malamud, the mechanism of action of eribulin is “slightly different from that of the other microtubules, in that eribulin inhibits the growth phase rather than shortening the phase of the microtubules.”
In an open-label, phase 3, randomized, multicenter clinical trial investigating the safety and efficacy of eribulin, the drug extended overall survival (OS) by 2.5 months: median OS was 13.1 months with eribulin (N = 508) compared with 10.6 months in the control group (N = 254), a significant difference (P = .041).
Ongoing Patient Monitoring
As with all chemotherapeutic agents, patients must be monitored on an ongoing basis and must be asked directly for any potential adverse events. “If I don’t ask them, they don’t tell me,” said Dr Malamud.
Indeed, he added, “the incentive for patients to stay on [chemotherapy] is usually so great that they are usually willing to forgo some symptomatology, so you have to push them to find out what’s going on.” When adverse events occur, Dr Malamud cautioned, “adjust dosing, hold dosing to maintain functionality.”
The most common adverse events in clinical trials have been neutropenia and peripheral neuropathy. Of 503 participants in one trial, severe neutropenia lasting >1 week occurred in 12% of patients, leading to discontinuation of eribulin in <1% of patients. Grade 3 peripheral neuropathy occurred in 8% of the patients and grade 4 in 0.4%. Peripheral neuropathy was the most common cause for therapy discontinuation in phase 1 and phase 3 clinical trials.
Embryo-fetal toxicity has not been well studied with eribulin; however, it is expected to cause harm to the fetus when used during pregnancy.