had partial or complete tumor shrinkage, according to a final analysis of 112 patients in a clinical trial. The most common severe side effects were lowered potassium levels and lowered counts of platelet cells in the blood. But importantly, researchers didn’t see the heart damage that has been observed in other trials of the standard trastuzumab.
This week in San Antonio, researchers will look at another 100-patient study of patients who are getting their third round of treatment. These are patients who failed to respond to the standard trastuzumab and a competing drug from GlaxoSmithKline called lapatinib (Tykerb). If this drug can show that it can shrink tumors for a high percentage of patients who have failed those other treatments, it could be enough for Roche to whip up an application for regulatory approval. If the data aren’t very persuasive, the companies will have to wait longer for the results of other studies, such as a more time-consuming 580-patient study that started enrolling patients in February.
When I stopped by his office a few weeks ago, Junius wouldn’t define for me how well T-DM1 must perform in the 100-patient study being presented in San Antonio. But if the data is “compelling,” he says, then Roche will file an application in 2010 for patients getting their third-line of treatment. Then the plan is to systematically start pushing the drug into progressively larger patient populations, he says. By 2012, the application could be ready for patients getting their second round of therapy, to be followed that year or shortly thereafter by patients getting their first round of treatment.
If all that goes according to plan, and the drug continues to show a relatively mild side effect profile for a cancer drug, then it could be used by the wider population of patients who have had their breast tumors surgically removed and appear healthy, but take what’s known as “adjuvant therapy” as a preventive measure to lower their risk of recurrence. Clinical trials that showed the original trastuzumab worked for those women have been a boon to Roche’s bottom line. Yet Junius says his partner is willing to cannibalize
