Adding Roche’s new medicine Perjeta to Herceptin — which could double the current monthly cost of $6,100 — resulted in about 1 percentage point of improvement in the proportion of women who lived at least three years without tumors returning. For patients with less severe cancer, where tumors hadn’t spread to the lymph nodes, Perjeta didn’t help at all.

The results, presented Monday in Chicago at the world’s largest gathering of cancer researchers, are a disappointment and probably won’t justify moving a majority of patients to Roche’s pricey new combo treatment, doctors say. Researchers had warned that it would be tough to top Herceptin, which revolutionized treatment for women with an aggressive type of breast cancer called HER2-positive after Roche introduced it in 1998.

Roche Holding’s new breast cancer combination therapy barely outperformed a current gold-standard drug for the disease — the company’s own decades-old Herceptin — in its latest study.

‘‘There are going to be people who look at the presentation and are a little disappointed that the benefits aren’t greater,’’ said Eric Winer, director of the Breast Oncology Center at the Dana-Farber Cancer Institute in Boston. ‘‘On the other hand, for those people who thought about it carefully, this is probably not very surprising.’’


The late-stage results presented at the American Society of Clinical Oncology’s annual meeting come at a critical time for the Swiss giant, which faces the first competition from cheaper copies of Herceptin as early as this year.

The underwhelming Roche data could benefit Puma, which also has an experimental drug used in addition to Herceptin. The Food and Drug Administration will decide on the Puma medication in July, after an advisory panel recommended its approval last month.

Roche officials welcomed its combo results, saying women with higher-risk tumors, including those that had spread to the lymph nodes or wouldn’t respond to hormone therapy, derived the most benefit. The goal of treatment is a cure, and reducing the development of invasive disease would give thousands more a shot at a cancer-free life, said Sandra Horning, Roche’s chief medical officer.


‘‘We are talking about life-and-death issues in the early breast-cancer setting,’’ she said.

Harold Burstein, an associate professor of medicine at Harvard Medical School and institute physician at Dana-Farber, agreed that the combination therapy will be valuable in higher-risk patients. He estimated that as many as 25,000 of the 250,000 people diagnosed with breast cancer in the United States each year might benefit.

The initial benefit seen in the trial increased over time, according to Gunter von Minckwitz, lead researcher on the Roche study.

‘‘To have a full assessment not only on the long-term effect but also on long-term safety, this is just something that needs more time,’’ said von Minckwitz, who is president of the German Breast Group in Neu-Isenburg. ‘‘It is reasonable to give this to patients.’’

One in four women taking Herceptin eventually developed a recurrence in an older test, so reducing the risk of relapsing is critical, said Daniel O’Day, head of Roche’s head of pharmaceuticals.

Still, an editorial in the New England Journal of Medicine, where the results of the study were simultaneously published, rejected the idea that a longer follow-up could lead to a very different result. It also concluded that the improvement from adding Perjeta was ‘‘a disappointment’’ compared with the benefits seen before surgery or for women with advanced disease. What’s more, it said the investigators didn’t properly analyze the drug’s potential effect on the heart in the trial.