Abstract 3592: Targeting SWI/SNF ATPases in enhancer-addicted human cancers
Bibliographic record
Abstract
Abstract In mammalian cells, DNA is wrapped around histone octamers (collectively referred to as nucleosomes) which form a physical barrier to all DNA-based processes. The switch/sucrose non-fermentable (SWI/SNF) is a multi-subunit chromatin remodeling complex that uses energy from ATP hydrolysis to reposition or eject nucleosomes at non-coding regulatory elements, thereby enabling access to the underlying DNA for transcriptional activation. Notably, the SWI/SNF complex plays a crucial role in chromatin remodeling and is recurrently altered in over 20% of human cancers, with the revised complex in cancer cells enabling central oncogenic gene programs. Yet, no studies have assessed the therapeutic efficacy of complete SWI/SNF inactivation across human cancers. Here, we developed a proteolysis targeting chimera (PROTAC) degrader of ATPase subunits of the SWI/SNF complex, SMARCA2 and SMARCA4. In a panel with over 90 normal and cancer cell lines from 18 different lineages, we found MYC-driven multiple myeloma and androgen receptor (AR)/forkhead box A1 (FOXA1)-positive prostate and breast cancers to be preferentially sensitive to dual SMARCA2 and SMARCA4 degradation relative to benign prostate as well as other cancer cell lines, including cancer cell lines with inactivating SMARCA4 mutations. We found complete SWI/SNF ATPase degradation to instantaneously compact the cis-regulatory elements that are bound and activated by transcription factors that drive cancer proliferation, namely MYC, IRF4, TCF3, AR, FOXA1, and ERG. This ensued in parallel untethering of these oncogenic drivers from the chromatin, with subsequent chemical decommissioning of their core enhancer circuitry and attenuation of downstream gene programs. Furthermore, using chromatin conformation assays we found SWI/SNF inactivation to disrupt super-enhancer and promoter DNA looping interactions that wire supra-physiologic expression of the MYC, AR, ERG, IRF4, and TCF3 oncogenes themselves, thereby tempering their expression in cancer cells. Treatment with the SMARCA2/4 degrader alone induced potent inhibition of tumor growth in cell line-derived xenograft models of multiple myeloma, as well as prostate cancer, and synergized with AR antagonists, inducing disease remission in several drug-resistant disease models. Notably, no major toxicities were seen in mice upon prolonged treatment with the SMARCA2/4 degrader, including no indications of thrombocytopenia, gastrointestinal goblet cell depletion, or germ cell degeneration—all being major toxicities associated with the BRD4-targeting therapeutics. To our knowledge, this study is the first preclinical proof of concept that targeted obstruction of chromatin accessibility at non-coding regulatory elements can be a potent therapeutic strategy in enhancer-addicted tumors, warranting the safety and efficacy assessments of SWI/SNF inhibitors and degraders in human clinical trials. Citation Format: Abhijit Parolia, Lanbo Xiao, Yuanyuan Qiao, Pushpinder Bawa, Sanjana Eyunni, Eleanor Young, Rahul Mannan, Sandra E. Carson, Yu Chang, Yuping Zhang, James George, Mustapha Jaber, Fengyun Su, Rui Wang, Sanjita Sasmal, Leena Khare, Subhendu Mukerjee, Chandrasekhar AbbinenI, Kiran Aithal, Xuhong Cao, Yuzhuo Wang, Susanta Samajdar, Murali Ramachandra, Arul M. Chinnaiyan. Targeting SWI/SNF ATPases in enhancer-addicted human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3592.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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) | 0.002 | 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 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".