Trial results for a Phase 2 study evaluating pembrolizumab in combination with olaparib for Triple Negative Breast Cancer (TNBC) or Hormone Receptor-positive HER2-negative Breast Cancer were posted on ClinicalTrials.gov on 2026-05-29. The study reported that 5 of 6 participants in the combination arm achieved a pathologically negative MRI-guided biopsy.
Background
This study investigated the combination of pembrolizumab and olaparib in participants with Triple Negative Breast Cancer (TNBC) or Hormone Receptor-positive HER2-negative Breast Cancer. The trial aimed to assess the effects of these study drugs when given prior to standard surgical procedures, with a focus on tumor shrinkage and potential improvement in surgical outcomes.
Trial design
The Phase 2 study (NCT05203445) enrolled 6 participants with Triple Negative Breast Cancer (TNBC) or Hormone Receptor-positive HER2-negative Breast Cancer. The trial's objective was to evaluate the effects of combining pembrolizumab and olaparib administered before standard surgical procedures. The study aimed to determine if the combination could shrink the cancer by a certain percentage, potentially improving surgical outcomes.
Key results
The trial reported results for pathologically negative MRI-guided biopsy in the Olaparib in Combination With Pembrolizumab group:
- 5 participants achieved a pathologically negative MRI-guided biopsy.
- 1 participant did not achieve a pathologically negative MRI-guided biopsy.
What this means
These early Phase 2 results suggest a potential signal for the combination of pembrolizumab and olaparib in treating Triple Negative Breast Cancer (TNBC) or Hormone Receptor-positive HER2-negative Breast Cancer. With 5 out of 6 participants achieving a pathologically negative MRI-guided biopsy, the findings indicate a high rate of response in this small cohort. However, given the very limited enrollment of only 6 participants, these results are preliminary and require validation in larger, more comprehensive studies. Clinicians and researchers will need to consider these findings as exploratory, pointing towards a promising direction for further investigation into this combination therapy for breast cancer.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT05203445, titled "A Study of Olaparib and Pembrolizumab in People With Triple Negative Breast Cancer (TNBC) or Hormone Receptor-positive HER2-negative Breast Cancer", were posted on 2026-05-29 on clinicaltrials.gov.