What's Hot at SABCS
What's Hot at the 32nd Annual San Antonio Breast Cancer Symposium
December 3, 2009 — New studies evaluating the possible influence of oral bisphosphonates on breast cancer incidence and investigating the effectiveness of trastuzumab (Herceptin, Genentech) in the adjuvant setting headline the offerings at the 32nd Annual San Antonio Breast Cancer Symposium.
Speaking with Medscape Oncology, director of the meeting, C. Kent Osborne,MD, called special attention to a late breaker that features new data from the North Central Cancer Treatment Group (NCCTG) N9831 trial. The study evaluates chemotherapy and the sequential or concurrent addition of 52 weeks of trastuzumab in operable HER2-positive patients (stages I to III).
"It's an exciting report," said Dr. Osborne, who is director of the Dan L. Duncan Cancer Center at Baylor College of Medicine in Houston, Texas. "It will provide guidance on how to use trastuzumab in the adjuvant setting," he added.
The NCCTG investigators, including meeting presenter Edith Perez, MD, from the University of Miami in Florida, previously published 3-year outcomes data from the study (N Engl J Med. 2006;354:640-644). But this latest report, to be presented on December 12, details new "longterm" data, said Dr. Osborne.
Another large phase 3 study of trastuzumab in the adjuvant setting will be presented during the same meeting session.
The Breast Cancer International Research Group (BCIRG) will present updated data from its 006 trial. This trial, however, does not evaluate the timing of the administration of trastuzumab.
Instead, it compares outcomes in patients treated with chemotherapy alone and chemotherapy plus trastuzumab. These data will be presented by Dennis Slamon, MD, from the University of California, Los Angeles.
But the Big Story Is . . .
The headline grabber of the meeting is likely to be a study from the landmark Women's Health Initiative that evaluates the relation between the use of oral bisphosphonates and breast cancer incidence.
The study will be presented on the afternoon of December 10 by Rowan T. Chlebowski, MD, PhD, from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in California.
"The bisphosphonates are taken for bone preservation," noted Dr. Osborne, but he added that previous data with intravenous formulations suggest that they also have an effect on cancer. Indeed, at last year's symposium and at the 2008 American Society of Clinical Oncology meeting, studies were presented indicating that zoledronic acid (Zometa Novartis) either shrunk tumors or reduced relapse rate in early breast cancer.
The use of bisphosphonates and the risk for postmenopausal breast cancer is the subject of a presentation from Israeli investigators; it will follow Dr. Chlebowski's presentation.
The effect of bisphosphonates on aromatase-inhibitor-associated bone loss is the subject of a number of presentations at the meeting.
Five-year final follow-up data will be presented on the Z-FAST study, which looks at the effect of zoledronic acid on aromatase-inhibitor-associated bone loss in postmenopausal women with early breast cancer receiving adjuvant letrozole (Femara, Novartis Pharmaceuticals). The study will be presented on December 11 (poster session 4) by Adam Brufsky, MD, from the University of Pittsburgh Cancer Institute in Pennsylvania.
Another presentation on zoledronic acid compares it with the novel experimental product denosumab (Amgen), which is close to launch. This study will compare effects that the 2 agents have on the incidence of skeletal-related events in breast cancer patients with bone metastases. On the afternoon of December 10, Alison Stopeck, MD, from the University of Arizona in Tucson, will present the results.
Denosumab can inhibit osteoclast activity that is associated with bone destruction and skeletal-related events, which are the hallmarks of bone metastases from breast cancer. Denosumab, a monoclonal antibody directed against RANKL, a key mediator in bone turnover, is a "first in its class" product.
More Data on Aromatase Inhibition
The symposium will also feature 2 presentations on major clinical trials of the aromatase inhibitor exemestane(Aromasin, Pharmacia).
The Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial compares exemestane as initial adjuvant therapy with a sequential approach of tamoxifen followed by exemestane. The 5-year data will be presented on the morning of December 10 by Daniel Rea, MD, PhD. from the University of Birmingham in the United Kingdom.
An updated analysis of the international Intergroup Exemestane Study (IES) will be presented during the same session. The presentation will focus on disease-related outcomes; shorter-term data from this trial, which evaluates the use of exemestane or tamoxifen after 2 to 3 years of initial tamoxifen treatment, have already been published ( Lancet.2007;369:559-570).
Exemestane is molecularly different from the other 2 aromatase inhibitors, anastrozole (Arimidex, AstraZeneca) andletrozole, noted Dr. Osborne. "Exemestane is a type 1 inhibitor — the others are type 2 — and once it binds to the enzyme, it does not come off," he said.
New Data on Alcohol
Clinicians will also likely be interested in 2 studies of modifiable risk factors for breast cancer, namely alcohol consumption and obesity. "We know these 2 are risk factors for developing breast cancer," said Dr. Osborne.
What is notable this year is that there are new studies on the effects of alcohol and obesity in women who already have breast cancer. There is some previous research in this area, said Dr. Osborne, but "these are more definitive studies."
The Life After Cancer Epidemiology (LACE) Study examines the association between alcohol consumption (overall and type) and breast cancer recurrence and overall mortality in a prospective cohort of early-stage breast cancer survivors. The study will be presented on the morning of December 10 by Michelle Kwan, PhD, from Kaiser Permanente in Oakland, California.
It will be followed immediately by a presentation on the effect of obesity on the prognosis of women with early breast cancer. This Danish study will be presented by Marianne Ewertz, MD, from Odense University Hospital in Denmark.
32nd Annual San Antonio Breast Cancer Symposium. December 9-13, 2009.