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 (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 and doxorubicin. In
addition, they will be randomized to receive as concurrent therapy
either weekly placebo or antibody to HER2.