SABCS executive committee member selects his best bets at 2009 meeting

SAN ANTONIO, TEX.-Clinical updates on the mother of all monoclonal antibodies and the link between bone and breast health will be ones-to-watch at SABCS 2009.Peter Ravdin, MD, PhD, shared his presentation picks at this year’s meeting with Oncology News International. Dr. Ravdin is on the SABCS executive committee and is based at the University of Texas Health Science Center in San Antonio.

“Two of the most interesting stories coming out of this meeting are on the maturation of the use of trastuzumab [Herceptin] and the use of bisphosphonates” Dr. Ravdin said. “Trastuzumab made a splash when it was introduced and previous studies have given us many good answers about its use, but they’ve also raised important questions.”

The trastuzumab studies will be presented on December 12 during a general session. First up is an updated survival analysis from a trial of lapatinib (Tykerb) alone or in combination with trastuzumab in women with HER2-positive metastatic breast cancer whose disease is progressing while they are receiving therapy (abstract 61). Then Dennis Slamon, MD, will present phase III results from the BCIRG 006 study, which compared several treatment regimens that used some combination of doxorubicin, cyclophosphamide, docetaxel (Taxotere), carboplatin, and trastuzumab in HER2/neu-positive early breast cancer patients (abstract 62). “These two major updates will address incredibly important questions,” Dr. Ravdin said.

There are also two late-breaking abstracts on trastuzumab that Dr. Ravin highlighted:

• Transcriptional and post-translational upregulation of HER3 (ErbB3) counteracts antitumor effect of HER2 tyrosine kinase inhibitors (abstract 63) 

• Analysis of Fcγ receptor IIA & IIIA polymorphisms: Correlation with outcome in trastuzumab-treated HER2/neu-amplified early and metastatic breast cancer patients (abstract 64)
 

Abstract 63 offers insight into why some cancers are resistant to HER2 tyrosine kinase inhibitors , while abstract 64 explores the relationship between FcR genotypes and trastuzumab efficacy.

On the topic of bisphosphonates, “we’re really waiting for the other shoe to drop so to speak,” Dr. Ravdin said. Previously, the AZURE trial and the Austrian Breast and Colorectal Cancer Study Group showed that zoledronic acid (Zometa) can double complete pathologic response and decrease the risk of disease recurrence.

But those studies were done in premenopausal women, Dr. Ravdin said. “The question is: How general are these data? There are two presentations [at SABCS 2009] that look at populations that are taking bisphosphonates for osteoporosis and address whether we see a protective benefit in women who are otherwise healthy.”

Results from the prospective Women’s Health Initiative and another late-breaking presentation (abstracts 21 and 27) will reveal whether oral bisphosphonates can affect breast cancer risk. Both of these studies will be delivered during a general session on December 10.

Finally, Dr. Ravdin will chair a mini-symposium on host-related factors in breast cancer on December 11. The symposium will focus on modifiable risk factors and lifestyle choices in the general population that can decrease the risk of breast cancer recurrence. “Demonstrating that lifestyle modifications can affect cancer risk is important in this day and age where there is an emphasis on making healthcare more cost-effective,” Dr. Ravdin said.