Impact of concurrent antibiotics on survival with immunotherapy in metastatic colorectal and pancreatic cancer.
Bibliographic record
Abstract
2609 Background: The interplay between antibiotics and the microbiome has been hypothesized to modify the immune response to cancer and may negatively affect immune checkpoint inhibitor (ICI) efficacy. Methods: We retrospectively reviewed concurrent antibiotics received in the randomized phase II Canadian Cancer Trials Group (CCTG) CO.26 and PA.7 clinical trials. CO.26 evaluated dual programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibition (with durvalumab and tremelimumab) versus best supportive care only (BSC) in metastatic refractory colorectal cancer (CRC). PA.7 evaluated gemcitabine and nab-paclitaxel +/- durvalumab and tremelimumab in metastatic pancreatic ductal adenocarcinoma. In CO.26, T cell receptor sequencing (TCR-seq) was available at baseline and week 8. Results: In CO.26 (n=180), median (range) age was 65 (36-87) years, 33% (n=59) were female, and 29% (n=50) were ECOG 0. Concurrent exposure to antibiotics was associated with improved overall survival (OS) (7.4 vs 6.2 months, adjusted hazard ratio (aHR) 0.66 (95% confidence interval (CI) 0.46-0.93), p=0.018) in patients with metastatic CRC who received ICIs, but not in patients who received BSC (3.5 vs 4.5 months, HR 1.49 (95% CI 0.81-2.73), p= 0.20); (p-interaction=0.094). In antibiotic class analysis, concurrent exposure of ICIs to fluoroquinolones (9.4 vs 6.2 months, aHR 0.50 (95% CI 0.30-0.82), p=0.0067), but not penicillins or cephalosporins, was associated with improved OS. There was no difference in RAS/RAF status or tumor mutation burden in patients who received antibiotics/fluoroquinolones or not. The results were consistent when also controlling for TMB (antibiotics aHR 0.63 (0.44, 0.91), p=0.013; fluoroquinolones aHR 0.51 (0.31, 0.84), p=0.009). Patients treated with antibiotics did not have a different TCR diversity or clonality between baseline and 8 weeks (p=0.37 and p=0.47) compared to those who did not receive antibiotics (p=0.26 and p=0.60). In PA.7 (n=180), median (range) age was 65 (29-84) years, 48% (n=87) were female, and 24% (n=44) were ECOG 0. Antibiotics were not associated with OS in patients who did/did not receive ICIs (9.7 vs 10.8 months, HR 0.97 (95% CI 0.64, 1.46), p=0.87; 7.4 vs 10.3 months HR 1.22 (95% CI 0.72, 2.09), p=0.46, respectively). Fluoroquinolones were also not associated with OS regardless of whether or not the patient received ICI therapy (10.9 vs 9.8 months, HR 0.74 (95% CI 0.47, 1.15), p=0.18; 7.2 vs 10.2 months, HR 1.18 (95% CI 0.62, 2.27), p=0.62). Conclusions: Concurrent exposure to antibiotics, and specifically fluoroquinolones during ICI therapy was associated with a statistically significant improvement in OS in patients with metastatic CRC, but not metastatic pancreatic cancer. This is discrepant from prior reports in other tumor types and suggests that the gut microbiome may impact ICI efficacy uniquely in patient with CRC. Clinical trial information: NCT02870920 , NCT02879318 .
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| 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".