You’re listening to Breaking Boundaries in Breast Cancer on ReachMD, sponsored by Lilly.
On this episode, we’ll hear from Dr. Sara Tolaney, breast medical oncologist at the Dana-Farber Cancer Institute and the principal investigator of a phase Ib study presented at the 2020 ASCO Annual Meeting. She’ll be reviewing the findings of that study and what it could mean for our patients with HER2 positive breast cancer.
Let’s hear from Dr. Tolaney now.
I think there is definitely more interest in trying to see how immunotherapy fits into the HER2 landscape. Certainly, the landscape is dense with multiple new agents that are emerging, and I think there will be large shifts in our therapeutic approach over the next year or 2 as more studies get reported.
We had conducted a trial looking at T-DM1 with pembrolizumab. The rationale for this study was really to better understand what the safety would be of administering checkpoint inhibition with an antibody drug conjugate, specifically with T-DM1. At the time this study was developed, there was no data that was available for such a combination, and so the study was really exploring the safety and then getting a signal for efficacy with a small expansion cohort. The study demonstrated that amongst the 20 patients that enrolled to the trial, their regimen was well-tolerated with no real new safety signals that were identified, and the recommended phase II dose of the combination was the standard T-DM1 dosing at 3.6 mg/kg every 3 weeks in combination with pembrolizumab at 200 mg IV every 3 weeks. There were no dose-limiting toxicities that were identified within the safety run-in for the trial.
When looking at the efficacy for patients enrolled, we can see that amongst the 20 patients that enrolled, there was a 20 percent% objective response rate that was seen with a median progression-free survival of about 9.6 months. We had tried to explore whether or not PD-L1 and TILs were associated with efficacy, but given the small sample size, it was challenging to statistically evaluate.
I think our findings are really just able to assess the safety and tolerability for T-DM1 with pembrolizumab and really suggests that it is a safe and well-tolerated combination, and I think the efficacy signal that we’re seeing, again in a small number of patients, is encouraging. Given the data, there is interest in trying to think about how better to develop the combination.
That was Dr. Sara Tolaney discussing her phase Ib study investigating the safety and tolerability of administering T-DM1 with pembrolizumab to patients with HER2 positive breast cancer. To revisit any part of this discussion and to access other episodes in this series, visit ReachMD.com, where you can Be Part of the Knowledge. Thank you for listening.