ASCO LOS ANGELES--Two multi-institutional phase II studies of recombinant human anti-HER2/NEU antibody (rhuMAb HER2) in heavily pretreated stage IV breast cancer patients show some impressive responses, including some hepatic responses and a 25% response rate in patients given the antibody plus cisplatin(Drug information on cisplatin) (Platinol).
The antibody is directed at the product of the HER2 oncogene, a growth factor receptor, which is overexpressed in 30% of primary breast cancers and is associated with worse prognosis, said Jose Baselga, MD, of Memorial Sloan-Kettering Cancer Center.
As monotherapy in 43 patients, the antibody produced one complete and four partial responses (11.6%), including hepatic responses, Dr. Baselga said. Response duration ranged from 1 month to a still ongoing complete response at 23 months. The agent was well tolerated.
In the combination trial, presented by Dr. M. Pegram of UCLA, 9 of 36 evaluable patients responded, all with partial responses (median duration, 5.3 months).
This compares favorably with studies of single-agent cisplatin in similar patient populations, Dr. Pegram said. Of five such studies in the literature, the overall response rate was about 7% and responses were of brief duration.
A phase III trial is ongoing in which patients with measurable metastatic breast cancer will receive as front-line therapy a standard regimen based on cyclophosphamide(Drug information on cyclophosphamide) and doxorubicin(Drug information on doxorubicin). In addition, they will be randomized to receive as concurrent therapy either weekly placebo or antibody to HER2.