Early results from a study presented at the San Antonio Breast Cancer Symposium show that two medicines used together before surgery substantially increased pathologic complete response rates in HER2 positive early-stage breast cancer. In this study, pathologic complete response (pCR) meant that, after surgery, tests no longer found signs of invasive disease.
The NeoALTTO study considered a combination of trastuzumab (Herceptin) and lapatinib (Tykerb) before surgery. Early results showed that, when used together, these medicines were almost twice as effective as when used alone. Two other studies that also considered the use of combined anti-HER2 medicines before surgery returned similar results.
The Reason for the Study
HER proteins regulate cell growth, as well as other cell functions. When there is too much HER2 protein present, it makes cells grow uncontrollably, particularly in some breast cancers. Both trastuzumab and lapatinib specifically target the HER2 protein and interrupt this uncontrolled cell growth.
These types of medicines interfere with the HER2 protein. Researchers wanted to consider the potential impact of combining these two medicines as a treatment before surgery.
The primary goal of this study was to determine if neoadjuvant therapy—a therapy that is applied before the main treatment—that combined two anti-HER2 medicines would significantly influence pathologic complete response rates after surgery.
The study’s 455 participants, at about 130 sites in approximately 30 countries, were randomly assigned to three groups. One group received lapatinib daily for six weeks, followed by lapatinib daily plus the chemotherapy medicine paclitaxel (Taxol) weekly for an additional 12 weeks before surgery. The second group received trastuzumab weekly for six weeks, followed by trastuzumab plus paclitaxel weekly for an additional 12 weeks before surgery. The third group received lapatinib daily plus trastuzumab weekly for six weeks, followed by lapatinib daily, plus trastuzumab and paclitaxel weekly for an additional 12 weeks before surgery. After surgery, each group received 3 cycles of a fluorouracil-epirubicin-cyclophosphamide (FEC) combination, followed by 34 weeks of their assigned targeted therapy.
Study results indicate that the complete response rate was 51.3 percent for the group that had the combined neoadjuvant therapy of trastuzumab and lapatinib, while that rate was 29.5 percent for the trastuzumab-alone group and 24.7 percent for the lapatinib-alone group.
Jose Baselga, MD, PhD, the co-primary investigator on the study who presented the results at the San Antonio symposium, said that because the response rates increased so dramatically when both medicines were used, the dual blockade of HER2 is a promising area of study. The therapy needs more research before changes in practice can be considered, in part because lapatinib (Tykerb) is not yet available for early-stage disease outside of clinical trials.
What Does This Study Mean for Me?
The results of this study indicate promising developments for the future treatment of HER2-postive breast cancer. Although early, they show that dual anti-HER2 neoadjuvant treatment substantially boosts complete response rates in HER2 positive breast cancer.
Because strong pathologic response rates are not always associated with improvements in disease-free and overall survival it is not yet clear from this study that improvements in pathologic complete response will mean improved long-term outcomes. This is still being tested. Consult with your care team if you have questions, or if you are interested in exploring your eligibility for clinical trials investigating these treatment options.
Baselga J, Bradbury I, Eidtmann H, et al: First results of the NeoALTTO trial (BIG 01-06 / EGF 106903): A phase III, randomized, open label, neoadjuvant study of lapatinib, trastuzumab, and their combination plus paclitaxel in women with HER2-positive primary breast cancer. 33rd Annual San Antonio Breast Cancer Symposium. Abstract S3-3. Presented December 10, 2010.