their first look at how the two-antibody combo strategy performs in the third and final phase of clinical trials usually required for FDA approval.
Results of the 808-patient study, known as Cleopatra, are expected on Friday, Dec. 9 at 10:30 am Central. The study is designed to ask whether a combination of pertuzumab, trastuzumab, and docetaxel chemotherapy is better at keeping tumors from spreading when compared to the standard combination of trastuzumab and docetaxel. Genentech has already said that this study met its main goal, but what everyone wants to know is how much better the combo regimen really is.
What won’t be available in San Antonio is complete data on whether the new pertuzumab regimen helps patients live longer. The data on that question are still immature, and probably won’t be ready until 2013, Horning says. It will take time to follow up all the patients to see how long they live, she says.
The other significant study to watch for at the San Antonio conference will be for the souped-up version of trastuzumab known as T-DM1. That drug, which I profiled in depth in June 2010, is designed to combine the specific HER2 targeting capability of the original antibody with an attached toxin that gives it more tumor-killing kick.
Data from a mid-stage study known as TDM4450g was presented at a European meeting back in September. The drug has already shown an ability to keep tumors from spreading for a median of 14.2 months, compared with 9.2 months for standard trastuzumab and docetaxel. And T-DM1 has shown an ability to get the greater effectiveness while also reducing side effects.
The new data in San Antonio will be focused on whether T-DM1 offers improvement in quality of life. That’s a notoriously subjective, you might say squishy, kind of thing to measure consistently in a clinical trial. Horning says Genentech is using well-validated metrics. The data will be based on patients’ own reports on how much energy they feel, how much time they spend in bed, and other questions that get at quality of life rather than just length of life. Regulatory bodies have traditionally looked askance at this kind of data, but Genentech says it has sought to measure quality of life because of feedback from all kinds of players in the breast cancer world.
“We’ve heard loud and clear from the patient community, the physician community, advisory communities, payers, there’s a lot of interest in quality of life,” Horning says.
Taken together, the pertzumab and T-DM1 data is mounting, Horning says. “We are on the verge of seeing another step forward in managing HER2 positive disease,” she says.
