On December 7, 2017 Syros Pharmaceuticals (NASDAQ: SYRS), a biopharmaceutical company pioneering the discovery and development of medicines to control the expression of disease-driving genes, reported that new preclinical data on SY-1365, its first-in-class selective cyclin-dependent kinase 7 (CDK7) inhibitor currently in a Phase 1 clinical trial in advanced solid tumors, demonstrate anti-tumor activity across a broad panel of breast cancer cell lines and point to potential biomarkers predictive of response (Press release, Syros Pharmaceuticals, DEC 7, 2017, View Source [SID1234522431]). The Company also announced its identification of key genes driving relapse and metastasis in triple negative breast cancer (TNBC), pointing to potential new drug targets. These data were presented at the San Antonio Breast Cancer Symposium (SABCS).
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"These data speak to the power of our gene control platform to provide a new lens for understanding disease with important implications for developing much-needed therapies in defined subsets of patients," Eric R. Olson, Ph.D., Chief Scientific Officer of Syros. "Despite advances in the treatment of certain cancers, two of the biggest challenges in cancer treatment remain the ability to pair the right patients with the right drugs and to prevent the emergence of drug resistance in response to targeted therapies. By analyzing regulatory regions of the genome, we discovered potential biomarkers of response to SY-1365 within heterogeneous patient populations that we can further explore during clinical development. Separately, using our platform, we also identified new potential points of therapeutic intervention in TNBC with the potential to thwart the mechanisms cancer uses to become resistant to therapy and spread to other parts of the body."
New Preclinical Data on SY-1365
Syros scientists analyzed the anti-tumor activity of SY-1365 across a panel of more than 400 cancer cell lines, including 19 TNBC cell lines and 21 ER-positive, PR-positive and HER2-positive cells lines. They then grouped the cell lines according to sensitivity to SY-1365 and looked for markers of response using Syros’ gene control platform to analyze regulatory regions of the genome. The data showed:
SY-1365 induced cell death in 15 out of the 19 TNBC cell lines and 17 of the 21 ER-positive, PR-positive and HER2-positive cells lines.
Sensitivity to SY-1365 in these breast cancer cell lines was associated with a super-enhancer, a highly specialized regulatory region of the genome, that drives increased expression of the known oncogene MYC.
Sensitivity to SY-1365 was also associated with low expression of the mitochondrial apoptosis antagonist BCL2L1 in these cell lines.
Lowered expression of MCL1, a gene in the mitochondrial apoptosis pathway known to inhibit apoptosis, was associated with SY-1365 target engagement and anti-tumor activity in cell lines and a cell-derived xenograft model of TNBC.
The Phase 1 trial of SY-1365 is a multi-center, open-label trial enrolling patients with advanced solid tumors. The primary objective of the trial is to assess the safety and tolerability of escalating doses of SY-1365, with the goal of establishing a maximum tolerated dose and a recommended Phase 2 dose and regimen. The dose-escalation phase is open and expected to enroll approximately 35 solid tumor patients for whom standard curative or palliative measures do not exist or are no longer effective. Following the dose-escalation phase, expansion cohorts are planned to further evaluate the safety and anti-tumor activity of SY-1365 in patients with transcriptionally driven tumors and to enroll patients with tumors of any histology in a cohort focused on analyzing biopsied tumor tissue. Additional details about the trial can be found using the identifier NCT03134638 at www.clinicaltrials.gov. Syros expects to present initial clinical data from this study in 2018.
Mechanisms of Relapse and Metastasis in TNBC
Using its gene control platform, Syros scientists, in collaboration with the lab of Robert Weinberg, Ph.D. at the Whitehead Institute, analyzed regulatory regions of the genome in cancer-stem cell enriched TNBC cell lines. Cancer stem cells (CSCs) are known to be involved in resistance to chemotherapies, relapse of disease and development of metastasis. The analysis revealed key genes that may be involved in driving disease relapse and metastasis, with implications for the discovery and development of novel therapies for TNBC. Notably, TP73 was found to be a core driver of transcriptional circuitry in CSCs, controlling super-enhancer associated genes involved in cell migration, signal transduction and developmental processes. TP73 is a gene that encodes a DNA-binding transcription factor called p73. The set of TP73-controlled genes provide new leads for drug discovery and development with potential to yield much-needed new therapies for TNBC patients.