The median progression-free survival for patients receiving T-DM1 was 9.6 months, compared to 6.4 months in the group receiving Xeloda and Tykerb, a difference considered statistically significant.

WSJ: Roche Breast-Cancer Treatment Advances

In a tougher measure of efficacy that takes into account how long patients lived, called progression-free survival, Thalomid more than doubled the length of time patients lived, to 57 weeks.

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While the drug combo did meet the first goal of increasing progression-free survival, it failed to prolong overall survival beyond what is normal for patients on chemotherapy without Erbitux.

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Celldex CEO Anthony Marucci has said previously that a meaningful and positive response rate in the study would be 12% to 15% with a progression-free survival of greater than 12 weeks.

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The study was designed to measure progression-free survival, which is a measurement of the time from the start of treatment until the disease gets worse or the patient dies, and overall survival, which is a measurement of time from the start of treatment until death.

WSJ: Roche Breast-Cancer Treatment Advances