Design, synthesis, and biological evaluation of selective estrogen receptor modulator/histone deacetylase inhibitor hybrid drug molecules
Bibliographic record
Abstract
The prognosis for those diagnosed with breast cancer has dramatically improved since the 1980’s, primarily due to improved diagnostic and treatment methods. One such treatment is a class of drugs called selective estrogen receptor modulators (SERMs). SERMs are a popular treatment option for breast cancer, commonly employed as adjuvant therapy. Prototypical examples of SERMs are tamoxifen and raloxifene. Despite their widespread success, breast cancers can often develop resistance to SERMs. As a result, other biological targets which may mitigate this resistance have been identified. Recent interest in the field has arisen around histone deacetylases (HDACs), which are a class of enzymes that have been implicated in promoting resistance in breast carcinoma. Studies have demonstrated the combination treatment of SERMs and HDAC inhibitors (HDACi’s) elicits a cooperative effect in enhancing cytotoxicity and resensitizing resistant breast cancers. In an effort to maximize the cooperative effects of SERMs and HDACi’s, the project detailed in this thesis describes the design, synthesis, and biological evaluation of a series of hybrid raloxifene/HDACi molecules that combine the pharmacophores of both drug classes. Previous work by the Gleason laboratory found tamoxifen/HDACi hybrids to exhibit potent biological activity, but further exploration of these would be laborious due to their inherent instability. As a result, a synthesis of raloxifene/HDACi hybrids was developed. Significant synthetic challenges resulted from the comparatively electron-deficient nature of key intermediates, making known methods used for raloxifene inapplicable towards these targets. After notable route scouting and reaction optimization, these challenges were resolved and a small library of seven hybrid drug molecules were successfully synthesized and purified prior to biological evaluation. Fluorogenic HDACi assays determined the IC50 values of the raloxifene/HDACi hybrids against HDAC1 and HDAC6. All hybrids demonstrated sub-micromolar IC50 values for HDAC1. For HDAC6, one hybrid showed low micromolar potency for HDAC6, while all others had sub-micromolar values. Generally, carbon-linked hybrids were more potent than oxygen-linked hybrids against HDAC1, while the reverse was true for HDAC6.Preliminary biological assays performed by the Mader lab at the Université de Montréal demonstrate all hybrids antagonize the ER at a low micromolar dose, both in the presence and in the absence of E2. A more conclusive result of the SERM/HDACi hybrids can be drawn once further biological testing has been completed by the Mader lab
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.002 | 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".