Abstract P3-07-03: Real-world comparison of safety and effectiveness of dose dense (2-weekly) versus weekly paclitaxel given with trastuzumab as neoadjuvant treatment in HER2-positive early stage breast cancer
Bibliographic record
Abstract
Abstract Background: Traditionally, trastuzumab-based chemotherapy combinations used in HER2-positive early-stage breast cancer are delivered as 21-day cycles, either comprising weekly paclitaxel or 3-weekly docetaxel). In Ontario, Canada, an alternative dose-dense protocol allows the administration of 4 cycles of doxorubicin and cyclophosphamide (AC) followed by 2-weekly paclitaxel concurrently with trastuzumab over 4 cycles. Little is known about the effectiveness or safety of this schedule. Methods: A single institution, retrospective chart review of patients with HER2-positive early-stage breast cancer treated with neoadjuvant AC-Paclitaxel chemotherapy between the years 2015-2019 was performed. Comparative effectiveness of AC followed by 2-weekly (dose dense) or weekly paclitaxel regimens was assessed as the proportion of patients achieving pathologic complete response (pCR). Safety was assessed as the proportion of patients completing the course of treatment and of patients with cardiac toxicity defined by the ESC guidelines. Differences between regimens were evaluated as the test of 2 proportions (Z-test). Statistical significance was defined as p<0.05. Results: The initial analysis comprised 70 patients; 45 treated with 4 doses of paclitaxel 175mg/m2 every 2 weeks and 25 treated with 12 doses of paclitaxel 80mg/m2 weekly. Trastuzumab was given as an 8mg/kg loading dose and 6mg/kg maintenance dose, the latter either every 2 weeks or every 3 weeks based on paclitaxel schedule. The median age in the 2-weeks regimen was 54 years (30-77) and 55 years (35-71) in the weekly treatment. The 2-weekly regimen demonstrated a pCR proportion of 68% (31/45), while for weekly treatment, pCR was observed in 40% (10/25). This difference was statistically significant (p=0.023). Treatment completion rates were 100% (45/45) for the 2-weekly group and 64% (16/25) for the weekly group (p<0.001). There were no differences in the cardiotoxicity profiles between the protocols (p=0.68). The 2-weekly regimen resulted in cardiotoxicity in 6% (3/45) of patients, moderate cardiotoxicity in 2% (1/45), and no cases of severe cardiotoxicity. The weekly regimen reported mild cardiotoxicity in 4% (1/25) of patients, no moderate cardiotoxicity, and severe cardiotoxicity in 8% (2/25). Conclusion: In this retrospective study, both completion rates and pathologic complete response (pCR) rates were more favourable when AC was followed by 2-weekly paclitaxel/trastuzumab regimen compared to weekly paclitaxel/3-weekly trastuzumab. There was no difference between cardiac toxicity between the two schedules. An expanded dataset as well as an analysis of healthcare delivery costs, will be reported at the meeting. Citation Format: Yael Berner-Wygoda, Eitan Amir, Chloe Perlon, Diego Malon, Michelle B. Nadler, Jacqueline Savill, Meredith Li, Massimo Di Iorio, Neha Pathak. Real-world comparison of safety and effectiveness of dose dense (2-weekly) versus weekly paclitaxel given with trastuzumab as neoadjuvant treatment in HER2-positive early stage breast cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P3-07-03.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".