Responses to Anti-HER2 MoAb Seen

ASCO LOS ANGELES--Two multi-institutional phase II studies ofrecombinant human anti-HER2/NEU antibody (rhuMAb HER2) in heavilypretreated stage IV breast cancer patients show some impressiveresponses, including some hepatic responses and a 25% responserate 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 primarybreast cancers and is associated with worse prognosis, said JoseBaselga, MD, of Memorial Sloan-Kettering Cancer Center.

As monotherapy in 43 patients, the antibody produced one completeand four partial responses (11.6%), including hepatic responses,Dr. Baselga said. Response duration ranged from 1 month to a stillongoing 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 cisplatinin similar patient populations, Dr. Pegram said. Of five suchstudies in the literature, the overall response rate was about7% and responses were of brief duration.

A phase III trial is ongoing in which patients with measurablemetastatic breast cancer will receive as front-line therapy astandard regimen based on cyclophosphamide and doxorubicin. Inaddition, they will be randomized to receive as concurrent therapyeither weekly placebo or antibody to HER2.