SAN ANTONIO – The treatment of patients with high-risk breast cancer who gave low results for the HER2 receptor with trastuzumab (Herceptin) did not provide any benefit in disease-free survival in women treated with chemotherapy alone, researchers reported. here.
Overall survival free of invasive disease at 5 years was 89.2% of women treated with chemotherapy alone compared to disease-free survival of 89.6% in women receiving chemotherapy and trastuzumab ( P ] = 0.90), reported Louis Fehrenbacher, MD, of Kaiser Permanente Northern California in Vallejo.
"We observed a 95% overall survival in both arms of the trial," he told MedPage Today at the 2017 San Antonio Breast Cancer Symposium.
Invasive disease events occurred in 134 women who received only chemotherapy and 130 women who received chemotherapy plus trastuzumab during the 5 years of the study, Fehrenbacher reported at a press conference of SABCS. and.
The trial was sparked by a finding in the 2005 National Surgical Slug and Intestinal Surgical (NSABP) study B-31. Its main finding was an advantage for trastuzumab in women with overexpression of the HER2 receptor, but it also found a possible advantage in a small subset of women who were apparently mistakenly identified as having overexpression but actually had low levels of HER2. Fehrenbacher and his colleagues wanted to confirm if this was real or some kind of coincidence.
Apparently it was the last one.
"In general, we do not present studies with negative findings, but these results are very important because we have many patients who are 1+ and 2+ and we have been asking ourselves if we should give them a very expensive drug with side effect for a year complete, "said Virginia Kaklamani, MD, of UT Health in San Antonio.
Why the current study, designated as NSABP B-47, did not confirm that the previous result can not be easily explained, Fehrenbacher said. He speculated that, in the previous study, the cases of HER2-low could have been HER2-positive. The findings in the original trial showed a trend toward benefit in the small group of patients, but these findings did not reach statistical significance.
To seek the possible use of HER2-targeted agents in this expanded breast cancer community with low HER2, Fehrenbacher and colleagues enrolled 3,270 women who identified with HER2-low breast cancer by immunohistochemistry (1+, 2+ ), a level that would not normally be treated with trastuzumab.
They received chemotherapy at their provider's choice, either doxorubicin 60 mg / m 2 and cyclophosphamide 600 mg / m 2 in four cycles every 3 weeks followed by 12 weeks of paclitaxel once a week; or docetaxel 75 mg / m 2 plus cyclophosphamide 600 mg / m 2 every 3 weeks for six cycles. Chemotherapy alone was randomized to 1,603 women; Chemotherapy plus trastuzumab was administered to 1,599 women. There were 63 patients (1.9%) lost during follow-up.
"This will probably reduce the amount of trastuzumab that is being used, although it should not," Fehrenbacher said. "There were probably a few cases in which women had low or close to HER2 levels, but not exactly the 3 needed.I think the number of these patients being treated with trastuzumab is quite low at this time, but that number should be Go to zero, there was no benefit and there was toxicity, it's slow and expensive. "
He said that there were no statistically significant differences when looking at stratification by HER2-low status level; for the number of positive lymph nodes; by hormone receptor status; or by type of chemotherapy. "No trends were observed for efficacy," he said.
Fehrenbacher said that the high survival was somewhat surprising: "These patients did extremely well, and if you look at the results of more than 30 years, you will see that there is a gradual improvement in the same decades of cancer after decade, whether it is due to a lower stage diagnosis, less risk in the same stage, or maybe the treatment is better, the organization is better to provide care … it is difficult to know why, but it is very clear that the results in each stage are improving ".
Fehrenbacher revealed relevant relationships with Genentech / Roche, CellDex, Abbvie, Macrogenitcs, Cascadian and Pfizer.
Kaklamani revealed relevant relationships with Novartis and Pfizer.
Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Planner Nurse
2017-12-06T16: 45: 00-0500