464 Anti-CTLA-4 therapy depletes Tregs and expands ICOS<sup>+</sup> T-cells in neuroblastoma tumors with induced DNA mismatch repair deficiency
Bibliographic record
Abstract
<h3>Background</h3> Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) highly expressed on regulatory T-cells (Tregs) inhibit the activation of pro-inflammatory T-cells responsible for eliminating cancer cells. Anti-CTLA-4 can enhance T-cell activation by increasing CD28 co-stimulatory signaling through CTLA-4 blockade or depletion of Tregs by Fc-dependent effector mechanisms. Strategies to improve its therapeutic efficacy are needed as patient response rates to anti-CTLA-4 are low. Response to anti-CTLA-4 has been positively correlated with tumor mutation burden (TMB). Defects in the DNA mismatch repair (MMR) pathway can increase TMB and the production of neoantigens that promote anti-tumor immune responses. Here we investigate the underlying mechanism(s) to which induced MMR deficiency in an immunologically-cold and low TMB tumor model can enhance the therapeutic effect of anti-CTLA-4. We hypothesize that induced MMR deficiency in tumors enhances anti-CTLA-4-mediated Treg depletion and increases the infiltration and activation of effector T-cells. <h3>Methods</h3> MMR deficiency was induced in a syngeneic murine neuro-2a neuroblastoma cell line by knocking-out <i>MLH1</i> expression using CRISPR-Cas9. Wildtype MMR-proficient (pMMR) or induced MMR-deficient (idMMR) neuro-2a cells were inoculated into immunocompetent A/J mice and treated with anti-CTLA-4. Tumors were immunophenotyped by flow cytometry and mixed-lymphocyte reaction assays were used to examine the effects of MMR deficiency and anti-CTLA-4 on T-cell activation and proliferation. <h3>Results</h3> Induced MMR deficiency in neuroblastoma tumors enhances the anti-tumor immune response induced by anti-CTLA-4. MMR deficiency in neuroblastoma tumors promoted anti-CTLA-4-mediated Treg depletion and increased intratumoral CD3<sup>+</sup> T-cells. idMMR neuroblastoma tumors had an increase of ICOS<sup>+</sup> T-cells compared to pMMR tumors. In addition, ICOS<sup>+</sup> T-cells were increased further with anti-CTLA-4 treatment. <h3>Conclusions</h3> Our data show that inducing MMR deficiency in low TMB and immune-cold neuroblastoma tumors can enhance the anti-tumor effect of anti-CTLA-4 by increasing T-cell activation and depletion of Tregs. By understanding the underlying mechanism(s) of anti-CTLA-4 in idMMR tumors, it may justify targeting the MMR pathway to improve the response to immune checkpoint inhibitors in patients with immunologically-cold and/or low TMB tumors that are refractory to immunotherapy. Future studies will assess how inducing MMR deficiency alters the tumor microenvironment to enable anti-CTLA-4-mediated Treg depletion and the significance of ICOS<sup>+</sup> T-cells in the efficacy of anti-CTLA-4 therapy in this setting.
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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 | 0.000 | 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 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".