Dana-Farber Cancer Institute's Dr. Sara Tolaney from the ASCENT-03 stud in breast cancer. The data further strengthens the case for approval of sacituzumab govitecan as first-line treatment for patients with advanced triple-negative breast cancer.
The Ascento 3 study was a randomized phase 3 trial that was for patients who had previously untreated metastatic triple negative breast cancer, and these were patients who were not candidates for a checkpoint inhibitor. They were randomized in a 1 to 1 fashion to get saccetuzumab govitecin, uh, which we'll call SG for short, or to get chemotherapy of physician's choice, and the design offered and provided crossover treatment with SG to those patients who had centrally confirmed disease progression on the chemotherapy arm. And we'd previously seen the data for the primary endpoint which was progression-free survival, where we saw a statistically significant and I think clinically meaningful improvement in PFS with a hazard ratio of around 0.6. And at ASCO this year we are presenting an exploratory analysis of PFS 2. So PFS 2 is defined from the time of randomization to time of progression on second line of therapy, and this can be a really important endpoint when you're trying to understand longer term outcomes. And at this point in time, overall survival data remains immature, with less than 40% of events having occurred. Um, but what we saw in the PFS2 analysis was that scetuzumab govitecan was associated with a much longer PFS-2, um, going from about 14 months in the control arm to 18 months with SG, and I think this is very meaningful because we know that a little over 80% of patients in the control arm who got a second line of treatment. Went on to get an ADC and so because you have such a high crossover rate, you're trying to understand what the implications are of getting SG earlier in the first line versus getting it potentially later in the second line. And to me this does imply that getting it earlier is very important for patients because we are seeing a much longer PFS 2. So I think a really informative finding from this trial.
