Eribulin in Metastatic TNBC: Real-World Data

Sarah S. Mougalian, MD:Randomized clinical trials are designed with very specific inclusion and exclusion criteria. For example, they may restrict to age, prior therapies, medical comorbidities, or lab test values to make the sample under study as homogenous as possible, such that any conclusions that are drawn from the results of the clinical trial are attributable to the thing that’s being tested.

However, once a drug or medication is FDA approved, there’s a lot less supervision and a lot less monitoring of the use of these particular drugs. And so, physicians use their training and their clinical judgment to determine which patients are most likely to benefit from particular agents.

In the real world, in real-world analyses, we’re looking at how these drugs are actually being used—in what settings, in what patients—and how effective they are. It gives us a much better glimpse of how these drugs are used in real life. Probably fewer than 5% of patients in the United States are enrolled in clinical trials. So there’s a whole other 95% of the population, which we’re not addressing in clinical trials. Real-world evidence tries to get at the experience of those patients with the use of these medications.

In our study, we defined early use of eribulin as first- or second-line therapy, and later use as third-line therapy and higher, trying to distinguish between those who were following the FDA indication and those who were using it perhaps earlier in the treatment of triple-negative metastatic breast cancer. We worked with a network of community providers provided by Cardinal Health. And in that network, we asked providers to fill out case report fills on patients who had received eribulin.

We received back about 250 completed case report forms. What we were looking for was: what did providers report as the overall response rate? And what we found was very high rates of overall response.

Nearly 70% of women were reported to have had a response to eribulin when used in the first- or second-line setting. Nearly 50% of women were reported to have a response when it was used in the third or higher line. These are higher rates of response than were reported in the clinical trials. This is probably due to a multitude of factors, including the fact that responses were reported by the providers treating the patients and not central review.

Furthermore, there was no set clinical measurement interval. However, these real-world data do support the use of eribulin in even the most heavily pretreated of patients. And I think it gives clinicians and community oncology providers some additional data, some additional support for the use of eribulin in a variety of settings.

I think that this real-world data does support the use of eribulin, even in earlier settings; not just in accordance with the FDA approval.

Transcript edited for clarity.