The ASCO Annual Meeting, held from May 31- June 4 in Chicago, included more than 30,000 attendees which included specialists, patient advocates and industry representatives from the U.S. and around the world.
As more breakthroughs continue to be unveiled, researchers aim to refine their findings to help physicians and patients make decisions tailored to their type of breast cancer. At this year’s meeting, updates from groundbreaking studies on early-stage breast cancer were presented.
ER-positive/ HER2-negative breast cancer.
At last year’s ASCO Annual Meeting, the TAILORx clinical trial made headlines. The trial, supported in part by BCRF, revealed that 70 percent of women diagnosed with early-stage breast cancer could forego chemotherapy (opting for anti-estrogen therapy alone).
These finding were based on recurrence score results from the Oncotype DX® test, a blood test for early-stage breast cancer patients may undergo. If a patient received a score that was low (0-10) or intermediate (11-25), the study found no added benefit of chemotherapy. However, the results were less clear for women under 50 with an intermediate Oncotype DX® recurrence score of 16-25, for whom chemotherapy reduced the risk of recurrence.
This year researchers shared updates from the TAILORx trial bringing clarity to predicting risk of breast cancer recurrence in women under 50. In a secondary analysis, the investigative team sought to determine whether integration of recurrence score and clinical risk stratification – where the patient’s tumor size and histologic grade were taken into consideration – could help identify premenopausal women who might stand to benefit from more aggressive anti-estrogen therapy, such as ovarian suppression.
The analysis showed that for women under 50 with a recurrence score of 16-15, the addition of clinical risk stratification improved risk prediction. The clinical assessment did not improve risk prediction in low or high recurrence risk categories or in post-menopausal women. You can watch this short video with TAILORx lead investigator and BCRF researcher, Dr. Joseph Sparano discussing the results.
HER2-positive breast cancer. With the success of targeted therapies, HER2-positive breast cancer is now a treatable disease with several options. The standard approach includes neoadjuvant (pre-surgical) chemotherapy with one or more HER2-targeted therapies. Additional therapy after surgery includes chemotherapy plus HER2-directed therapy to reduce the risk of recurrence. For patients who show a pathological complete response (PCR) after neoadjuvant therapy, less therapy may be warranted.
In clinical trials, PCR after neoadjuvant therapy (no residual tumor at time of surgery) is often used as a prognostic marker and predictor of outcome. Questions remain however, on how residual disease after neoadjuvant therapy should guide subsequent adjuvant therapy.
This was illustrated by results presented from the KRISTINE trial, a phase III, randomized trial, which compared T-DM1 (trastuzumab emtansine) plus pertuzumab —a HER2-targeted regimen that omits standard chemotherapy—with the standard regimen of docetaxel, carboplatin, trastuzumab, and pertuzumab. Presenting the final analysis from the trial Dr. Sarah Hurvitz, University of California, Los Angeles, noted that patients with residual tumor cells after neoadjuvant therapy were equally like to experience disease progression regardless of the type of subsequent adjuvant therapy. She summarized that while no benefit was seen with TDM-1 without chemotherapy, patients reported less toxicity when compared with standard treatment.
In discussing results from KRISTINE and other ongoing clinical trials in early-stage, HER2-positive breast cancer, BCRF investigator, Dr. Mark Pegram stressed the challenges and opportunities in understanding the biology of the residual tumor to guiding subsequent adjuvant therapy, which may or may not include chemotherapy. Some large tumors may be good responders, he noted, but because of their initial mass, may not be completely eliminated by neoadjuvant therapy. These patients may do well to continue of HER2-directed therapy alone.
In other cases, the cells left behind after neoadjuvant therapy may be resistant to continued HER2 treatment. Understanding how to tell which the case is, is important to the patient and doctor in treatment decisions. “The burden is on us,” Dr. Pegram noted, “to identify molecular, genetic, imaging markers to identify patients who are most suitable for consideration of de-escalation strategies with T-DM1 or newer HER2 antibody-drug conjugates.”
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