Trial results for the study (NCT03237572) investigating pembrolizumab combined with focused ultrasound (HIFU) in patients with metastatic breast cancer were posted on ClinicalTrials.gov on 2026-02-09. The study evaluated the change in CD8+ tumor infiltrating lymphocytes (TILs), reporting a mean change of 126.39 when pembrolizumab was administered before HIFU, compared to 35.98 when given after HIFU.
Background
This pilot study evaluated the use of high-intensity focused ultrasound (HIFU) combined with pembrolizumab in patients with metastatic breast cancer. The trial aimed to understand the impact of the timing of pembrolizumab administration relative to HIFU on immune response markers.
Trial design
The study (NCT03237572) was a Phase 1 pilot study that enrolled 13 participants with breast cancer. Participants were randomized into two groups: one group received their first dose of pembrolizumab after HIFU, and the other group received their first dose of pembrolizumab before HIFU.
Key results
The trial measured the "Change in Proportion of CD8+ Tumor Infiltrating Lymphocytes" as a key outcome. The results for this outcome were:
- For participants in Arm A, who received the first dose of pembrolizumab after HIFU, the mean change was 35.98 (Standard Deviation: 64.38) in the ratio of CD8 to CD4.
- For participants in Arm B, who received the first dose of pembrolizumab before HIFU, the mean change was 126.39 (Standard Deviation: 216.16) in the ratio of CD8 to CD4.
What this means
These preliminary results suggest that the timing of pembrolizumab administration relative to HIFU may influence the immune response in patients with metastatic breast cancer. Specifically, administering pembrolizumab before HIFU was associated with a greater mean change in the proportion of CD8+ tumor infiltrating lymphocytes compared to administration after HIFU. This finding warrants further investigation to understand the clinical significance and potential optimization of this combination therapy.
Source
The information for these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03237572, titled "Focused Ultrasound and Pembrolizumab in Metastatic Breast Cancer," were posted on 2026-02-09 on clinicaltrials.gov.