Real-World Outcomes Favor Standard Care in HER2-Positive Metastatic Breast Cancer

By: Gregory Laub

From: medpagetoday.com

After the results of CLEOPATRA, taxane chemotherapy with dual anti-HER2-blocker therapy Herceptin [trastuzumab]/Perjeta [pertuzumab] became the standard of care for HER2-positive metastatic breast cancer. With this study, we were looking to see how many patients in the real world received that regimen as a first-line standard-of-care therapy, which we defined as “1LSOC” compared to an alternative regimen, which we defined as an alternative regimen.

This study was a retrospective cohort [study] using the Flatiron electronic health medical database, and this study essentially looked to answer the question of how many patients received the standard treatment 1LSOC versus alternative treatment.

This included patients from 280 U.S. clinics, which ended up being about 800 cancer centers, and patients were obtained through this retrospective registry. After patients were selected for eligibility, which had to be metastatic breast cancer with HER2-positive cancer, 3,277 patients were included in the final review.

In terms of the demographics, the ages of patients were very similar. Most of the patients were in the late 50s to early 60s setting, 75% of patients were from the community setting as opposed to a quarter of patients that came from the academic medical centers. Things that were different among the two cohorts was the number of patients with de novo metastatic disease. In our 1LSOC cohort, 61% of patients had de novo metastatic disease compared to 32% in the alternative regimen group. Similarly, 34% of patients had recurrent cancers in the 1LSOC group, and 57% of patients had recurrent cancers in the alternative group.

Another differing feature among the two groups was 61% of patients were HR [hormone receptor]-positive in the 1LSOC cohort compared to 74% of patients that were HR-positive in the alternative group. Finally, 7% of patients had brain mets [metastases] in the 1LSOC cohort, and 11%, so slightly more, had brain mets in the alternative regimen cohort.

In terms of the results, real-world progression-free survival was longer in the 1LSOC group. This was a difference of 9 months versus 14 months. Real-world time to next treatment was also longer in the 1LSOC group. That was a difference of 6 months versus 16 months. Real-world time to next treatment-2, which was the subsequent line, was also longer in 1LSOC. That was a change from 17 months to 30 months. And real-world PFS2, which was once again the subsequent PFS or progression-free survival, was also prolonged in favor of 1LSOC, which was 18 versus 26 months.

Finally, the differences were seen in favor of the 1LSOC group, which meant that patients that received the first-line standard-of-care therapy — which is the taxane, trastuzumab/pertuzumab — they did better than patients that received an alternative regimen.

We do call out some factors that could have contributed to that — for example, a higher proportion of patients that were HR-positive in the alternative cohort, a higher proportion of patients with de novo disease in the 1LSOC cohort, and more patients with brain mets in the alternative cohort.