Real-World Data Support the Use of Later-Line Eribulin in Metastatic Breast Cancer

Investigators aimed to determine if oncologic outcomes of patients in the real-world setting matched those of a pivotal clinical trial that led to the approval of eribulin mesylate in patients with metastatic breast cancer.

A retrospective, multisite review of medical records published in Advances in Therapy provided real-world evidence supporting the effectiveness of eribulin mesylate (Halaven) in patients with metastatic breast cancer, including triple-negative disease.1

The agent, which was approved in 2010, treats patients who have received at least 2 prior lines of chemotherapy in the adjuvant or metastatic setting, including an anthracycline and taxane.

“This retrospective chart review study reinforces the clinical effectiveness of eribulin in a large, diverse cohort of [patients with metastatic breast cancer], including the TNBC subtype, when used according to the approved US indication in clinical practice,” wrote the investigators, led by Sarah S. Mougalian, MD.

According to the investigators, the rationale for the trial stems from the poor generalizability of clinical trial results, which tend to be performed on younger, healthier, and less diverse participants than are present in the general population.

The analysis included records of 513 patients, of whom 45.4% had hormone receptor–positive, HER2-negative disease and 49.9% had triple-negative breast cancer (TNBC). The median age of patients was 59.0 years and 38.8% of patients had an ECOG performance status of 2 or greater. In 78.0% of patients, eribulin represented the third line of treatment, with the remainder in a fourth line or later. Across all patients, visceral disease was present in more than 90% of patients with metastases commonly seen in the lung (66.7%) and liver (57.3%).

In all patients, the objective response rate (ORR) was 54.4%. The median progression-free and overall survival were 6.1 months (95% CI, 5.8-6.6) and 10.6 months (95% CI, 9.9-11.7), respectively. In patients with TNBC, the ORR was 49.4%, with a median progression-free survival of 5.8 months (95% CI, 5.1-6.4) and a median overall survival of 9.8 months (95% CI, 8.6-11.0).

The 12- and 24-month survival rates in the overall cohort were 43.9% (95% CI, 39.6%-48.2%) and 23.9% (95% CI, 20.2%-27.7%), respectively. Corresponding rates in patients with TNBC were 40.3% (95% CI, 34.3%-46.3%) and 17.6% (95% CI, 13.1%-22.6%).

The authors on the study used these data as a comparison with the pivotal phase 3 EMBRACE trial (NCT00388726) that was published in The Lancet in 2011.2 Key differences from the current analysis included lower racial diversity (4% African American participants vs 26.3%), lower performance status (8% with an ECOG performance status of 2 vs 38.8% with ECOG ≥2), and a lower proportion of TNBC (19% vs 49.9%).

Despite differences in the patient population, measures of progression-free and overall survival were similar between the 2 studies. Additionally, the overall response and clinical benefit rates were higher in the present analysis (54.4% and 56.7%, respectively) compared with EMBRACE (12% and 23%).

Limitations of the study include its retrospective design and potential for provider selection bias. Additionally, responses were physician reported which may have overestimated the benefits of therapy compared with standardized assessment criteria used in clinical trials.

“For oncologists and people living with metastatic breast cancer, these data provide insights into HALAVEN real-world practice,” Takashi Owa, Vice President, Chief Medicine Creation Officer, and Chief Discovery Officer of the Oncology Business Group at Eisai, said in a press release.3 “We have remained committed to the continued data generation for HALAVEN, both in the real-world setting and in translational research related to mBC, to drive our continued innovation for difficult-to-treat diseases like mBC.”

References

1. Mougalian SS, Kish JK, Zhang J, Liassou D, Feinberg BA. Effectiveness of Eribulin in Metastatic Breast Cancer: 10 Years of Real-World Clinical Experience in the United States. Adv Ther. 2021;38(5):2213-2225. doi:10.1007/s12325-020-01613-6

2. Cortes J, O’Shaughnessy J, Loesch D, et al. Eribulin monotherapy versus treatment of physician's choice in patients with metastatic breast cancer (EMBRACE): a phase 3 open-label randomised study. Lancet. 2011;377(9769):914-923. doi:10.1016/S0140-6736(11)60070-6

3. Halavan [prescribing information]. 2010. Eisai, Inc. Accessed May 26, 2021. https://bit.ly/3fInyGy