Eribulin Induces Two-Year OS Rate in More Than Half of Patients With mBC

Peter A. Kaufman, MD

Real-world findings show that eribulin (Halaven) demonstrated an estimated 2-year overall survival (OS) rate of 53.6% (95% CI, 35.1%-68.9%) in patients with metastatic breast cancer (MBC) who previously received atezolizumab (Tecentriq) or sacituzumab govitecan (Trodelvy), according to a poster presented at the 39th Annual Miami Breast Cancer Conference®.

“The treatment landscape for MBC has been rapidly evolving over the [past] few years with FDA approvals of multiple new therapies, including, for example, several immune checkpoint inhibitors and antibody-drug conjugates,” senior author Peter A. Kaufman, MD, said. “Eribulin is a unique chemotherapeutic agent [that is] FDA approved and widely used in the treatment of MBC in both the USA and worldwide. There has previously been very little data on the efficacy of eribulin in patients with MBC who have been previously treated with either of these classes of medications.” Kaufman is a professor of medicine in the Division of Hematology/Oncology at Larner College of Medicine at the University of Vermont in Burlington.

The retrospective, noninterventional study included de-identified electronic health record data for 91 patients with MBC, which predominantly was triple-negative breast cancer (TNBC; 74.7%). After a median follow-up of 11.7 months from time of eribulin initiation, 63.7% of patients were alive and the median OS was not reached. The estimated 1-year OS rate was 77.8% (95% CI, 67.3%-85.3%). The estimated 1-year progression-free survival (PFS) rate was 62%; the 2-year PFS rate from the time of eribulin initiation was 41.9%.

“This type of study design certainly has a number of limitations, that I think are generally acknowledged and understood. Additionally, we are reporting on a relatively modest sample size, with 91 patients in total,” Kaufman said. “[Although] this is a real-world analysis with data obtained from a medical chart review—with the limitations of these types of studies and the other limitations of this study design—we find these results to be quite intriguing and warrant further study.”

Patients selected for the analysis were treated between March 1, 2019, and September 30, 2020. The analysis included 53 patients treated with prior atezolizumab (Tecentriq) and 38 who had received sacituzumab govitecan-hziy (Trodelvy). Patients were enrolled across various geographic regions of the United States, with the majority being in the South (34.1%) and the Northeast (28.6%). Those who received eribulin as part of a clinical trial or who developed a second malignant neoplasm were excluded from the study.

The median age of patients was 63 years. The next most common status after TNBC was HER2-negative and hormone receptor–positive, which comprised 13.2% of patients. Most patients did not have visceral disease (84.6%) and the majority were ECOG performance status 0 (15.3%) or 1 (68.2%).

In 75.8% of cases, eribulin was administered as a second-line therapy. The agent was administered in the third line for 13.2% of patients and fourth line in 11.0% of individuals. At the time of the analysis, 36.3% of patients continued to received treatment with eribulin. For those who remained on treatment, the median treatment duration was 12.2 months. Patients who discontinued eribulin stopped therapy after a median treatment duration of 5.1 months.

“As we noted in our poster, approximately 75% of these patients had TNBC,” Kaufman said. “Interestingly as well, what was reported in this medical chart review was that [approximately] 75% of these patients overall were receiving eribulin in the second-line setting, and approximately 25% were receiving eribulin in the third-line or later setting, which we found somewhat surprising. Nonetheless, we believe our findings to be quite intriguing.”

There were 7.7% of patients with unknown status at the last follow-up (n = 7), which may have been a result of patients transferring care to another provider or center, the authors noted. Moreover, the data represent just the patterns of those willing to participate and may not be broadly applicable, they said.

“Importantly, it should be noted this study is a medical chart review, and not a prospective clinical trial,” Kaufman said. “It is a real-world analysis of patients who received treatment with eribulin in routine clinical practice in a mixture of practice settings, specifically after previously receiving therapy with either atezolizumab or sacituzumab.”

_Reference

_{Goyal RK, Zhang J, Dhuliawala S, Sluga-O'Callaghan M, Kaufman PA. Real-world treatment patterns and clinical outcomes in patients treated with eribulin after prior immunotherapy (IO) or antibody-drug conjugate (ADC) for metastatic breast cancer. Poster presented at: 39th Annual Miami Breast Cancer Conference. March 3-6, 2022; Miami Beach, FL.}