halichondrin-b and Neutropenia

In the new era of 'precision' cancer medicine, new drug development has shifted from cytotoxic chemotherapy to molecularly targeted agents. Eribulin mesylate, a microtubule-destabilizing agent, is the only 'classical' cytotoxic agent approved for the treatment of breast cancer in the last 7 years. This synthetic analogue of halichondrin B, isolated from the marine sponge 'Halicondria Okaida', was responsible for prolonging overall survival of heavily pretreated metastatic breast cancer patients in a large Phase III trial. Eribulin is now under clinical development in earlier settings such as the neo-adjuvant and adjuvant settings. Furthermore, its unique mechanism of action and the absence of cross-resistance with taxanes have led to the design of clinical trials in multiple indications: bladder cancer, lung cancer, prostate cancer… The main adverse events are neutropenia, fatigue and peripheral neuropathy.

Topics: Alopecia; Antineoplastic Agents; Breast Neoplasms; Carcinoma; Chemotherapy, Adjuvant; Clinical Trials as Topic; Drug Approval; Drug Resistance, Neoplasm; Drugs, Investigational; Ethers, Cyclic; Fatigue; Female; Furans; Humans; Ketones; Macrolides; Molecular Targeted Therapy; Multicenter Studies as Topic; Neoadjuvant Therapy; Neutropenia; Peripheral Nervous System Diseases; Tubulin Modulators; United States; United States Food and Drug Administration

Eribulin is a synthetic analog of halichondrin B, a non-taxane microtubule inhibitor extracted from the marine sponge, Halichondria okaida. It presents a novel mechanism of action and is active on cancer cells resistant to other antimicrotubule agents. It was granted approval in the USA and Europe for the treatment of heavily pretreated metastatic breast cancer. Early trials had shown activity in this setting with main toxicities being neutropenia and neuropathy in patients where quality of life is essential. Approvals were granted after a phase 3 trial demonstrated overall survival benefit in metastatic breast cancer previously treated with anthracyclines, taxanes, and capecitabine, in a setting where most treatments are failing to demonstrate a survival benefit. Recent data suggest that this survival benefit is also consistent in the elderly with no excess toxicity. Future strategies of eribulin are being tested in ongoing trials, evaluating this drug in earlier metastatic lines as well as in the adjuvant and the neoadjuvant settings.

Topics: Adult; Aged; Antineoplastic Agents; Breast; Breast Neoplasms; Clinical Trials as Topic; Drug Monitoring; Ethers, Cyclic; Female; Furans; Humans; Ketones; Macrolides; Microtubules; Neoplasm Metastasis; Neutropenia; Treatment Outcome

Despite advances in cancer biology, chemotherapy remains the backbone of treatment approaches for many patients with metastatic breast cancer (MBC). Halichondrins, derived from marine sponges, have significant potential as potent antimicrotubule agents. Eribulin, with proven preclinical activity, is a synthetic halichondrin analog with novel actions on tubulin including suppression of microtubule polymerization. Phase I and II studies in MBC identified neutropenia as the dose-limiting toxicity and a maximum tolerated dose of 1.4 mg/m2 on days 1 and 8 of a 21-day cycle. An encouraging response rate of 11.5% in refractory MBC led to the launch of the phase III Eisai Metastatic Breast Cancer Study Assessing Physician's Choice versus Eribulin trial, in which heavily pretreated patients with MBC were randomized 2 : 1 to intravenous eribulin or monotherapy of the investigator's choice. Recently, it was reported that this important study of 762 patients met its primary endpoint of overall survival: eribulin was associated with an improvement in median overall survival from 10.65 months to 13.12 months (hazard ratio 0.8; 95% confidence interval 0.66-0.99) and a response rate of 12.2%. In general, the side effect profile of eribulin seems to be acceptable, as although neutropenia occurred in 45% of the patients, febrile neutropenia was rare and the incidence of neuropathy was low. These findings show that eribulin is potentially a new active agent for MBC, although results of ongoing studies are awaited to confirm the reported benefit. Future studies will investigate the potential role of eribulin in other settings, including for early breast cancer, to ascertain how to optimally incorporate this new agent into current treatment paradigms.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Breast Neoplasms; Clinical Trials, Phase III as Topic; Ethers, Cyclic; Female; Furans; Humans; Infusions, Intravenous; Ketones; Macrolides; Maximum Tolerated Dose; Middle Aged; Neoplasm Metastasis; Neutropenia; Randomized Controlled Trials as Topic; Survival Rate; Treatment Outcome; Tubulin Modulators

Eisai Co Ltd is developing eribulin, a simplified synthetic macrocyclic ketone analog of the tubulin inhibitor halichondrin B, for the potential treatment of cancer. Phase III trials are underway in the US and Europe for patients with breast cancer. Eribulin is currently in phase II trials for NSCLC and soft tissue sarcoma, and pancreatic, prostate, ovarian, fallopian tube, peritoneal and head and neck cancer, and phase I/II trials for urothelial cancers.

Topics: Alopecia; Animals; Antineoplastic Agents; Apoptosis; Cell Line; Cell Line, Tumor; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Drug Evaluation, Preclinical; Ethers, Cyclic; Fatigue; Furans; Humans; Hypoglycemia; Hypophosphatemia; Inhibitory Concentration 50; Ketones; Macrolides; Molecular Structure; Multicenter Studies as Topic; Nausea; Neoplasms; Neutropenia; Peripheral Nervous System Diseases; Randomized Controlled Trials as Topic; Survival Analysis; Tubulin Modulators; Xenograft Model Antitumor Assays