AstraZeneca Drug Could Enhance Breast Cancer Arsenal
By BETH M. MANTZ Of DOW JONES NEWSWIRES
NEW YORK -Post-menopausal women suffering from advanced stages of breast cancer may soon have a new weapon to add to their arsenal to fight the disease: AstraZeneca PLC's (AZN) Faslodex, first in a new class of drugs.
The injectable drug has yet to be approved, but clinical data, especially from late-stage human testing, is encouraging. So much so that AstraZeneca plans to file for U.S. Food and Drug Administration approval during the first quarter of next year to use the treatment in women with advanced stages of the disease after using other hormonal therapies.
At the 23rd annual San Antonio Breast Cancer Symposium Wednesday, researchers presented two late-stage phase studies testing Faslodex against another of AstraZeneca's breast cancer therapies, Arimidex, in post-menopausal women whose breast cancer has spread to other parts of the body or has returned after surgery. All of the patients had been previously treated with endocrine treatment, most likely tamoxifen, the therapy of choice for advanced breast cancer, before their cancer returned.
Lead investigator of the U.S. study, Kent Osborne of Baylor College of Medicine in Houston, and lead investigator of the European study, John Robertson, concluded that Faslodex has good efficacy in patients resistant to tamoxifen.
More importantly, "Faslodex is at least as effective as Arimidex in treating advanced breast cancer in postmenopausal women," said Osborne and Robertson at a press conference.
The more options to treat - and ideally beat - cancer, the better, said the investigators. Currently, advanced breast cancer patients follow a particular sequence of drugs to fight the disease: first tamoxifen, sold as either AstraZeneca's Nolvadex or Barr Laboratories Inc.'s (BRL) generic version; then Arimidex, which is another class of drugs called aromatase inhibitors that blocks the production of estrogen.
"The challenge with hormonal therapy is that if (patients) are treated with it in the first place, when the cancer returns, the hormonal therapy is not as effective," said Amy Langer of the National Alliance of Breast Cancer Organizations. "We need to give as many options as possible."
Faslodex appears one of those options, according to recent data.
Both the U.S. and European studies were double-blind and careful to include patients with relatively matching characteristics in each study arm. The average age was early 60's. The patients had relatively similar disease progression; if a certain number of patients in the Faslodex group had cancer which spread to the lung, the Arimidex group included a similar patients.
Both studies focused primarily on the question of the time to progression, but also looked at duration of response, objective response, time to treatment failure, and tolerability.
In the U.S. study of 400 women, the average time to progression in women injected with Faslodex was 5.4 months while in women swallowing the Arimidex pill, the average was 3.4 months.
Faslodex seemed to have a more lasting effect, nearly 9 months longer, than Arimidex. The duration of response from randomization to progression was 19.3 months in Faslodex patients and 10.5 months in Arimidex patients, and the duration of clinical benefit was 12.9 months with Faslodex and 10.9 months with Arimidex. At 24 weeks, about 51% of the Faslodex patients achieved stable disease compared with 36% of Arimidex patients.
The European study produced comparable results in the 451 women it studied, said Robertson.
The time to progression in the Faslodex patients was 5.5 months compared with 5.1 months with Arimidex. At 24 weeks, about 53% of the Faslodex group had stable disease and 67% of the Arimidex group had stable disease. The duration of response until progression was 14.3 months with Faslodex and 14.0 months with Arimidex, and duration of clinical benefit was 11.8 months with Faslodex and 11.4 months with Arimidex.
In both studies, the postmenopausal women tolerated Faslodex and Arimidex. Less than 3% of each patient group withdrew due to adverse events.
Side effects included hot flashes and gastrointestinal disturbances, but Osborne, of Baylor College of Medicine, said he doesn't think the drugs caused most of the reported incidence of maladies.
The U.S. study recorded every patient complaint, regardless of whether it was related to the drug, Osborne said. Many of the patients were experiencing hot flashes before the trial or were taking other drugs that could lead to gastrointestinal disturbances.
Weight gain and vaginitis were also reported as side effects in a small portion of the Faslodex and Arimidex patient groups.
The studies didn't contain survival data, but analysis will be carried out in the next 24 months.
More than 10,500 women have been diagnosed with advanced breast cancer, according to estimates from the American Cancer Society, but about one-third of women currently diagnosed with breast cancer will go on to develop advanced forms of the disease.
Since breast cancer can and does come back, effective treatments that improve the quality of life and prolong survival are in great demand. But the development of new drug classes has made a breast cancer diagnosis "no longer the death sentence it once was," said Langer of the National Alliance of Breast Cancer Organizations.
Researchers and AstraZeneca are studying Faslodex in other uses. Osborne said he expects to hear results comparing Faslodex with tamoxifen as a front-line therapy for advanced breast cancer next summer.
He added that researchers also need to determine if Faslodex works after patients have become resistant to Arimidex and vice versa. This knowledge could be used to create a more effective treatment chain.
Additionally, AstraZeneca plans to begin a trial testing the drug in early-stage breast cancer next year. |
