A Phase Ib Trial of Durvalumab in Combination with Trastuzumab in HER2-Positive Metastatic Breast Cancer (CCTG IND.229)
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Bibliographic record
Abstract
Abstract Background Immune checkpoint inhibitors are active in a broad range of cancers, including programmed death ligand 1 (PD-L1)-positive, triple-negative, metastatic breast cancer (MBC). Antibody-dependent cell-mediated cytotoxicity is a mechanism of action of trastuzumab. We performed a phase Ib trial of durvalumab and trastuzumab in HER2-positive MBC previously treated with chemotherapy and anti-HER2 antibodies to assess safety, efficacy, and correlative endpoints. Patients and Methods Patients with HER2-positive MBC were enrolled on a standard 3 + 3 design. Dose level 1 was durvalumab (1,125 mg intravenously day 1) and trastuzumab (8 mg/kg intravenously loading, then 6 mg/kg day 1) on a q3 weekly cycle. An expansion cohort at the recommended phase II dose (RP2D) performed tumor biopsies at baseline and after cycle 1. The primary endpoint was to establish the RP2D. Results Fifteen patients were accrued from April to December 2016, of which 14 were evaluable for response. Median age was 54 years (range 40–86); the majority had visceral disease (87%) and at least three prior (adjuvant and/or metastatic) lines of chemotherapy (73%), including trastuzumab (93%), pertuzumab (60%), and trastuzumab-emtansine (93%) for MBC. No dose-limiting toxicities were observed at dose level 1 (n = 6) or dose expansion (n = 9) during cycle 1. One patient developed a grade ≥3 immune-related adverse event (grade 4 diabetes mellitus). No responses by RECIST were seen, with 4 of 14 patients (29%) demonstrating stable disease as best response at week 6 (median duration, 2.7 months). All patients had <1% PD-L1 expression on either archival tissue (7/15) or prestudy biopsy (8/15). In the dose expansion cohort, evaluable pretreatment and on-treatment tumor biopsies (n = 5) showed minimal CD8 cell infiltration. Conclusion The RP2D of durvalumab and trastuzumab is standard full doses of both agents. No significant clinical activity was observed in patients with heavily pretreated HER2-positive PD-L1-negative MBC. Implications for Practice This phase Ib trial with associated correlative endpoints provides insights into the lack of activity of the combination of durvalumab and trastuzumab in heavily pretreated HER2-positive metastatic breast cancer (MBC). No significant clinical activity was observed in patients with heavily pretreated HER2-positive programmed death ligand 1 (PD-L1)-negative MBC with evidence of cytotoxic T-cell exhaustion. Furthermore, all patients had no expression of PD-L1 in the tumor cells. These data support the importance of PD-L1 as an important selection biomarker and the need to assess the tumor microenvironment for immune regulatory cells. Further work is needed to understand how to activate the “cold” tumors to be able to combine current immune-oncology agents.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it