Evaluating metrics of circulating tumor DNA response and progression using a high sensitivity tumor-agnostic assay in metastatic HR+/HER2- breast cancer receiving endocrine therapy and a CDK4/6-inhibitor.
Bibliographic record
Abstract
1043 Background: CDK4/6-inhibitors (-i) and endocrine therapy (ET) are first-line treatment for HR+/HER2- metastatic breast cancer (mBC). Clinical evaluation and cross-sectional imaging are used for treatment response assessment. The relationship between clinical/radiographic response and ctDNA dynamics using a high sensitivity tumor-agnostic assay is unknown in HR+/HER2- mBC. ctDNA monitoring in mBC may support clinical decision-making, enable new strategies for response assessment in clinical trials, and facilitate enrolment of patients lacking measurable disease (bone-only). Methods: Patients (pts) with HR+/HER2- mBC receiving ET and CDK4/6i were enrolled in a prospective cohort study. Plasma samples were collected at baseline (BL) and regularly on-treatment. Samples were analyzed using Guardant Infinity, a tumor-agnostic genomic and epigenomic platform. ctDNA-response (-R) was defined as a ≥50% decrease (dec) in methylation tumor fraction (mTF) from BL. ctDNA-progression (-P) was defined as a <50% dec in mTF from BL or any subsequent increase in mTF above an absolute mTF of 0.001% (cohort specific definition). Imaging outcomes and dates of treatment discontinuation (TD) were collected. Results: 57 pts with 350 clinical timepoints were evaluated. Median follow up was 28.2m (range: 1.6-66.0m). 42/57 (74%) pts received palbociclib and 40/57 (70%) received an aromatase inhibitor. ctDNA-R/-P was evaluable in 49/57 patients. ctDNA-P identified within the first 90d on CDK4/6i was not prognostic of TD (p=0.7972); when assessed between 90-180d it was prognostic of early TD (med: 6.3m vs. not reached; HR: 5.17, 95%CI: 1.04-25.7; p=0.0003). 156 matched radiographic and ctDNA assessments (blood collected within 30d of CT) were evaluable for ctDNA-R/-P and imaging concordance. Excluding those with clinician-identified sclerotic bone changes suggestive of treatment effect (n=5 events), adjudicated radiographic progression did not occur in the setting of ctDNA-R (NPV: 100%, sensitivity: 100%); no pts had clinical progression in the presence of ctDNA-R. ctDNA rise in the absence of radiographic progression occurred in 13 pts; 7/13 had TD (med: 10.1m, range: 3.0-21.9m) in the follow up period reflecting a molecular lead time. Blood first monitoring, using these metrics, could have avoided 104/150 (69%) staging CT scans in this cohort. Conclusions: ctDNA dynamics are associated with clinical outcomes in HR+/HER2- mBC. The use of a high sensitivity assay permits assessment of response in nearly all patients and suggests the possibility that radiographic surveillance could be reduced in patients with ctDNA-R. Prospective validation of these findings are required. Additional ctDNA-R/-P definitions and relationship with RECIST 1.1 criteria will be presented at the meeting.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".