A pharmacodynamic study of the epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 in metastatic colorectal cancer patients.
Bibliographic record
Abstract
PURPOSE: Epidermal growth factor receptor (EGFR) appears to play an important role in the pathogenesis of colorectal cancer. We have performed a Phase I/II study of the EGFR tyrosine kinase inhibitor ZD1839 in metastatic colorectal cancer patients in which serial biopsies were taken pre- and posttreatment to assess biological activity. EXPERIMENTAL DESIGN: Paired biopsies were obtained from colorectal cancer patients before and after treatment. Proliferation and apoptosis were assessed using Ki67 immunohistochemistry and terminal deoxynucleotidyl transferase-mediated nick end labeling assays, respectively. Immunohistochemistry for EGFR, activated EGFR, phosphorylated Akt, phosphorylated ERK, p27(Kip1), and beta-catenin was also performed. RESULTS: Posttreatment samples showed a statistically significant reduction in the cancer cell proliferation index (mean proliferation index pretreatment 31%; posttreatment 21%; P = 0.047). The mean cancer cell apoptosis index also increased from 6 to 12% in posttreatment samples, although this difference did not achieve statistical significance. All pretreatment samples showed strong staining for EGFR. Loss of immunohistochemical staining for activated EGFR, phosphorylated Akt, and phosphorylated ERK in cancer cells was observed in some patients after treatment. p27(Kip1) was absent in the cancer cells of most pretreatment biopsies; two patients showed a marked increase in staining for nuclear p27(Kip1) after treatment with ZD1839. These two patients also showed large increases in apoptotic index. CONCLUSIONS: ZD1839 inhibits EGFR signaling and proliferation in the cancer cells of patients with metastatic colorectal cancer. ZD1839 may also induce cancer cell apoptosis in a subset of colorectal cancer patients via up-regulation of p27(Kip1).
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How this classification was reachedexpand
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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 | 0.000 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".