HER2 Support Group Forums - Durable Complete Remission

A small retrospective study finds "durable complete remission," (modestly defined as 36 months without a recurrence) 9% of women receiving combination chemotherapy and Herceptin.

Here's what it says:

 By Kristina Fiore, Staff Writer, MedPage Today
Published: September 26, 2011
Reviewed by Vandana G. Abramson, MD; Assistant Professor of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Explain that of 120 patients with HER2+ metastatic breast cancer, 9% achieved a complete durable remission (disease free for at least three years) after being treated with chemotherapy and trastuzumab in first-line therapy.

Note that although a statistical analysis was not performed, durable complete remissions were associated with diagnosis in the sixth decade of life, ER negative disease, and liver-only disease.

STOCKHOLM -- A small proportion of metastatic breast cancer patients can achieve complete remission that lasts with trastuzumab (Herceptin) plus chemotherapy, researchers said here.

In a two-center study, almost 10% of HER2-positive metastatic breast cancer patients achieved a "durable complete remission," defined as being disease-free for at least three years, according to Giuseppe Gullo, MD, of St. Vincent's University Hospital in Dublin.

He reported the findings during a scientific session here at the European Multidisciplinary Cancer Congress, formerly known as the joint congress of the European Cancer Organization and European Society for Medical Oncology (ECCO-ESMO).

"It's not a statistical analysis," Gullo cautioned, "but durable complete remission is more frequently connected to being diagnosed in the sixth decade, being ER-negative, and having liver-only disease metastases."

Gullo explained that durable complete remission after treatment with trastuzumab and chemotherapy for HER2-positive metastatic breast cancer has been reported anecdotally in the literature, but there are a lack of data on its long-term outcomes.

There are also scant data on the optimal duration of maintenance trastuzumab after complete remission.

So he and his colleagues conducted a retrospective review of 120 patients who were treated between May 2000 and April 2011 with the combination therapy at two institutions, St. Vincent's University Hospital in Dublin and Humanitas Cancer Center in Milan.

The primary goal was to assess the long-term outcome of patients achieving durable complete response; secondary aims included exploration of the clinical features associated with this type of response.

Durable complete remission was defined by RECIST 1.1 criteria lasting at least 36 months.

Gullo and colleagues found that 11 patients, or 9% of the total population, achieved this level of remission during a median of 6.5 years of follow-up. Median age was 59 and the median duration of trastuzumab was 63 months.

Gullo cautioned that the research team did not perform a statistical analysis, but numerically, durable complete remission was linked with ER- or PR-negative disease or if they were diagnosed in their 60s.

Also, a larger proportion of those with durable complete remission had liver-only metastases compared with those who didn't have durable remission (55% versus 18%).

Three patients relapsed on maintenance trastuzumab -- at 49, 53, and 94 months, respectively.

Five patients discontinued maintenance trastuzumab, and only one of those had ipsilateral breast relapse 52 months after stopping the therapy, Gullo said.

He added that four patients are still on maintenance trastuzumab, and nine patients are still alive and in complete remission. Seven of them never relapsed.

Among those seven, the median age is 60, 71% are ER- and PR-negative, 57% have liver-only metastatic disease, and all had first-line chemotherapy plus trastuzumab -- four had docetaxel/carboplatin, two had a single-agent taxane, and one had capecitabine.

Gullo said the data suggest that in some cases of durable complete remission, maintenance trastuzumab can be safely discontinued with a very low risk of subsequent relapse.

"In our experience, discontinuation of maintenance trastuzumab was not associated with increased disease relapse," he said, again cautioning the lack of statistical analysis. "We can't answer the question about optimal duration, but discontinuation does not appear to be associated with relapse."

However, Martine Piccart-Gebhart, MD, PhD, of the Jules Bordet Institute in Brussels, said the study is "too small to suggest the discontinuation of trastuzumab after 36 months," a sentiment echoed by many in attendance at the session.

Piccart-Gebhart also noted that although seeing the characteristics that may be tied to durable complete remission, the study was "far too small to draw conclusions about clinical subgroups most likely to achieve long-term remission."

Still, she said, Gullo's is the first report on the long-term use of trastuzumab in the advanced setting, and it "points to the existence" of HER2-positive tumors that are "truly addicted to HER2," as they show long-lasting remission under the therapy.

Gullo said there's a need for further study of molecular and cytogenetic profiles of these tumors in order to better target which patients may be more likely to achieve durable complete remission on trastuzumab plus chemotherapy.

http://www.medpagetoday.com/MeetingCoverage/ECCO-ESMO