TCF7

A research team embarked on a quest to understand the diversity and cellular mechanisms of human Th2 cells. By conducting gene expression analyses of inflamed tissues, they pinpointed a subset of Th2 cells called Th2-MPP cells. Their findings suggested that these cells might serve as precursors to several crucial Th2 cell populations responsible for disease symptoms. These discoveries lay the groundwork for therapeutic interventions targeting these cells, potentially offering relief to patients living with allergic diseases. Currently, most therapies for allergic diseases require lifelong treatment. Allergic reactions, characterized by ongoing (type 2) inflammation in response to chronic antigen exposure, underlie many chronic diseases in humans, including asthma, atopic dermatitis, ulcerative colitis and more. T helper 2 (Th2) cells play an important role in the body's immune response, particularly in allergic reactions. Despite their central role, the sustained activity of Th2 cells during allergic reactions, even in the face of constant antigen exposure, has long puzzled researchers. A research team that included authors from Mass General Brigham, including members Brigham and Women's Hospital, Massachusetts General Hospital, and Mass Eye and Ear, embarked on a quest to understand the diversity and cellular mechanisms of human Th2 cells. By conducting gene expression analyses of inflamed tissues, they pinpointed a subset of Th2 cells called Th2-MPP cells. Their findings suggested that these cells might serve as precursors to several crucial Th2 cell populations responsible for disease symptoms. These discoveries lay the groundwork for therapeutic interventions targeting these cells, potentially offering relief to patients living with allergic diseases. Results are published in Nature Immunology. The research team created a single cell transcriptomic atlas, a comprehensive database of genes that are turned "on" and "off" in individual cells in the body, using inflamed tissues from patients with nine different chronic allergic diseases. They used this atlas to identify Th2-multipotent progenitor (Th2-MPP) cells, which chronically expressed two transcription factors, TCF7 and LEF1. These transcription factors allowed Th2-MPP cells to exhibit characteristics similar to stem cells in cancer and chronic infection, acting as progenitor cells that can give rise to other kinds of cells. The team also performed detailed studies on Th2 cells from nasal tissue in patients with chronic rhinosinusitis. They found that Th2-MPP cells could be the precursor for multiple types of Th2 cells that cause disease symptoms. "We still have much to learn about the contribution of progenitor cells to chronic human inflammation, but we are hopeful that the study of this area of immunity could provide opportunities for future disease-modifying therapeutic approaches," said senior author Patrick Brennan, MD, PhD, a physician-researcher in the Brigham Division of Allergy and Clinical Immunology. "Our work suggests that Th2-MPP cells have the potential to sustain type 2 inflammation in the face of chronic antigen exposure and lays the foundation for further investigation to better understand their contribution to disease," said lead author Radomir Kratchmarov, MD, a research fellow in the Brigham Division of Allergy and Clinical Immunology.

During infection, reversible switch permits flexible formation of memory T cells, long-lived blood cells that can remember pathogen encounters and respond upon reinfection. Unexpected findings have emerged about how and when certain infection-killing white blood cells decide to form memories about their encounters with a pathogen. It has been known for decades that these cells can turn themselves into durable memory cells that can survive a long time after an initial infection is cleared. They are prepared to quickly recognize and eliminate future intrusions by the same kind of pathogen. That is one reason people are resistant to some infectious diseases after exposure to or recovery from the illness. Vaccinations also work this way, by teaching the immune system to spot and attack dangerous viruses, parasites or bacteria. UW Medicine and University of Washington scientists, and their collaborators, wanted to pinpoint exactly when cytotoxic T lymphocytes, a type of immune white blood cell that directly destroys infected cells, decides to form memory during an infection. They used real-time, live imaging to observe these cells over the trajectory of their entire lineage. Their findings are published Jan. 31 in the journal Immunity from Cell Press. The co-lead authors are Kathleen Abadie and Elisa Clark, both National Science Foundation graduate fellows who recently finished their training in the laboratory of senior author Hao Yuan Kueh, UW associate professor of bioengineering, a joint department in the College of Engineering and the School of Medicine. "Our experiments revealed an unexpected degree of flexibility in memory decision making, whereby memory T cells are generated at multiple phases during the immune response," the research team wrote. "After encountering a pathogen, T cells decide early whether to form a memory, or alternatively, to become an effector cell, which has potent cell-killing abilities but is short-lived." They added, however, that after the pathogen is eliminated, effector cells can, in essence, change their minds and decide late to join the memory cell pool. Additionally, the researchers examined the molecular switch that underlies flexible memory formation in these cells. They learned that this switch acts on the key memory regulatory gene Tcf7. "This switch can turn off Tcf7 early in response to stimulatory signals due to infection," they explained. "However, importantly, this switch is reversible when these signals are gone, thus enabling cells that have gone down the effector trajectory to reverse their course." Why do T cells need leeway in their memory decisions? "For humans," Abadie noted, "having some degree of flexibility to change their minds after decisions have been made allows individuals to better adapt to uncertain and changing circumstances." The same might be true for T cells to respond effectively to different threats. An analysis of a mathematical model of T cell decisions, the researchers explained, shows that this flexibility allowed memory to form of both virulent pathogens that demand a large-scale immune response as well as of slow-dividing pathogens that don't try to overwhelm the immune system, but instead attempt to evade it. "The ability to make memory fate decisions at multiple junctures during an infection might also allow for greater responsiveness during the evolving situation of an immune challenge," the researchers added. These sorts of studies, Abadie and Clark noted, could resolve the longstanding uncertainty surrounding how and when memory cells form. They hope the findings will open new avenues of research on boosting long-term immune protection against a variety of infectious diseases and cancers. These studies were performed in collaboration with Jay Shendure, professor of genome sciences at the UW School of Medicine, and Junyue Cao, a former member of his lab, as well as with Armita Nourmohammad, UW associate professor of physics, and Obinna Ukogu, a graduate student in her lab. The Kueh lab team also worked with the lab of Rafi Ahmed at Emory University, together with co-lead author Rajesh Valanparambil, a member of the Ahmed lab. This study was funded by a National Institutes of Health National Institute of Biomedical Imaging and Bioengineering Trailblazer Awards (R21EB027327), an NIH National Human Genome Research institute grant (R01HG01632-01), National Science Foundation Research Fellowships, an NSF CAREER award (2045054) and startup funds from the Department of Bioengineering and the Department of Physics at the University of Washington, and the Rockefeller University. Shendure is an investigator of the Howard Hughes Medical Institute.

- Phase 2 Mechanism of Action Trial Results Demonstrate the Immunomodulatory Effects of Trilaciclib in the Tumor Microenvironment - - Trilaciclib Enhances Expression of Genes Associated with Memory T Cells - - Trilaciclib Increases Multiple Surrogate Immune Markers for Memory CD8+ T Cell Differentiation, Infiltration, and Function - RESEARCH TRIANGLE PARK, N.C., June 04, 2023 (GLOBE NEWSWIRE) -- G1 Therapeutics, Inc. (Nasdaq: GTHX), a commercial-stage oncology company, today presented results from 24 patients enrolled in its Phase 2, single arm mechanism of action study of trilaciclib administered as a single agent to patients with early-stage triple-negative breast cancer (TNBC) prior to receiving trilaciclib and neoadjuvant therapy. These results highlight the potential for trilaciclib to enhance long term immune surveillance by increasing T cell function and generation of certain memory T cells and demonstrate gene expression profiles that may be associated with improved clinical outcome. These data support earlier findings from this Phase 2 trial demonstrating an increase in the ratio of CD8+ T cells to regulatory T cells (Tregs); a high ratio of CD8+ T cell to Tregs is predictive of overall survival (OS) and is associated with pathologic complete response (pCR). As expected, high rates of pCR were observed in patients with PD-L1(+) tumors and in patients with inflamed tumor immune microenvironments. Data generated across multiple preclinical and clinical studies to date show that trilaciclib has the greatest effect on longer term endpoints including OS rather than earlier efficacy measures such as objective response rate (ORR), pCR, and progression free survival (PFS), consistent with other immunotherapies like checkpoint inhibitors. These results suggest that this is likely due to trilaciclib’s immune-mediated mechanism of action that protects the immune system from damage caused by cytotoxic therapy and enhances long-term immune surveillance by increasing the generation of certain memory T cells. This dual benefit may provide important longer-term benefits for patients by improving their ability to generate robust immune responses, particularly when treated with future subsequent therapies. “Trilaciclib is a highly active molecule that enhances T cell activation, favorably alters the tumor microenvironment, and improves long term immune surveillance; these new immune analyses help identify potential correlates of treatment response and extend our understanding of the mechanism,” said Raj Malik, M.D., Chief Medical Officer at G1 Therapeutics. “Trilaciclib drives increases in certain memory T cells which are important for longer term outcomes like overall survival, consistent with our understanding of the mechanism of action of trilaciclib.” These results are being presented today at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting. The poster, titled, “Neoadjuvant Single-Dose Trilaciclib Prior To Combination Chemotherapy in Patients with Early Triple-Negative Breast Cancer: Safety, Efficacy, And Immune Correlate Data from a Phase 2 Study,” can be found here. Patient Demographics As of the data cut date of April 3, 2023, all patients (N = 24) had received a median (range) of 16 (3–16) cycles of treatment; 21 (87.5%) patients received pembrolizumab, and 21 (87.5%) patients received carboplatin, per investigator discretion. All patients completed the study; five underwent definitive surgery prior to completing planned study treatment. At diagnosis, 79% of patients had stage II tumors and 88% had ductal carcinoma; 38% of patients had PD-L1+ tumors, consistent with early TNBC. Tumor immune microenvironment status was determined at baseline. All participants with immune-desert tumor microenvironments at baseline had PD-L1(-) tumors; an additional nine participants with immune-excluded tumor microenvironments had PD-L1(-) tumors. All participants with immune-inflamed tumor microenvironments at baseline had PD-L1(+) tumors; an additional five participants with immune-excluded tumor microenvironments had PD-L1(+) tumors. Data published by G1 and others show that trilaciclib can promote trafficking of immune cells out of the stroma and into the tumor microenvironment via chemokine release, thus leading to an inflamed tumor immune microenvironment status. Baseline Correlates of Clinical Outcome: Pathologic Complete Response (pCR) Tumor infiltrating lymphocytes (TIL) infiltration is associated with better outcomes with trilaciclib. In this mechanism of action trial, the pCR rate is higher (77.8%) in patients with PD-L1(+) tumors relative to that of the overall enrolled patient population. The pCR rate in the overall enrolled population (41.7%) is comparable to that of standard neoadjuvant therapy in this population of patients. As anticipated, the pCR rate was higher in patients with an immune-inflamed tumor microenvironment (75.0%) than those with immune-excluded (35.7%) or immune desert (33.3%) tumor microenvironments. The tumor status of four enrolled patients converted from PD-L1(-) at baseline to PD-L1(+) after trilaciclib monotherapy (day 7); 50% of these patients achieved pCR during the study. Immunomodulatory Effects of Trilaciclib Trilaciclib was shown to enhance the number and function of CD8+ T cells in the tumor microenvironment. Seven days after monotherapy with trilaciclib, the number of CD8+ T cells and GZMB+ cells, which is a surrogate marker for T cell function, were enhanced with statistical significance in patients achieving a pCR. There was also an increase in stromal TILs within the tumor microenvironment after a single dose of trilaciclib. RNA-sequence analysis revealed 59 genes that were differentially expressed seven days after single-dose trilaciclib in patients who achieved pCR, compared to those who did not. Furthermore, assessment of signaling pathways associated with pCR revealed significant enrichment in pathways associated with immune modulation including T cell receptor signaling and cytokine-cytokine receptor interaction that were not observed at baseline. Key genes associated with memory T cells - SELL (CD62L), IL-7R, and TCF7 - increased from baseline to Day 7, and a subset analysis based on pCR status revealed significant increases in these genes when individually assessed and as a gene signature among patients who achieved pCR. These results help confirm the role of trilaciclib in increasing the pool of functional memory T cells that could contribute to long-term immune surveillance and efficacy, as measured by longer term endpoints like OS. Safety Results (n=24) Trilaciclib continues to show a strong tolerability profile. Trilaciclib in combination with anthracycline (doxorubicin)/ cyclophosphamide/paclitaxel (AC/T) ± pembrolizumab ± carboplatin in the neoadjuvant setting for early-stage TNBC has a similar safety and tolerability profile as standard neoadjuvant regimens. The most common treatment-related adverse events (TRAEs; any grade) related to any study drug were fatigue, nausea, alopecia, and neutropenia/neutrophil count decreased. There were no adverse events leading to discontinuation of trilaciclib. Trilaciclib Phase 2 Mechanism of Action Trial Design Tumor tissue was obtained at baseline prior to study drug administration. Patients then received a single dose of monotherapy (240 mg/m2) trilaciclib, followed by a tumor biopsy approximately one week later to assess the ability of a single dose of trilaciclib monotherapy to favorably alter the tumor microenvironment. Paired tumor biopsies were available for 22 patients. Patients then entered the treatment phase in which trilaciclib is administered on day 1 of each cycle of anthracycline/cyclophosphamide for four cycles followed by trilaciclib administered on day 1 of each weekly cycle of taxane chemotherapy for 12 cycles. Pembrolizumab and/or carboplatin was added at the discretion of the investigator. Three to five weeks after the treatment phase, patients had definitive surgery and a final tumor tissue sample was collected if the patient has residual disease. pCR was assessed at definitive surgery by a local pathologist, per the current American Joint Committee on Cancer staging system . The primary objective was to evaluate the immune-based mechanism of action of a single dose of trilaciclib as measured by the change in the ratio of CD8+ T cells to Tregs in the tumor microenvironment. Secondary endpoints include assessment of pCR rate at the time of definitive surgery, and safety of the combination of trilaciclib with neoadjuvant regimen. Exploratory endpoints include assessment of the immune response, and identification of molecular and cellular biomarkers in tumor or blood samples that may be associated with clinical response/resistance, pharmacodynamic activity, and/or the mechanism of action of trilaciclib. About G1 TherapeuticsG1 Therapeutics, Inc. is a commercial-stage biopharmaceutical company focused on the development and commercialization of next generation therapies that improve the lives of those affected by cancer, including the Company’s first commercial product, COSELA® (trilaciclib). G1 has a deep clinical pipeline and is executing a development plan evaluating trilaciclib in a variety of solid tumors, including breast, lung, and bladder cancers. G1 Therapeutics is based in Research Triangle Park, N.C. For additional information, please visit www.g1therapeutics.com and follow us on Twitter @G1Therapeutics. G1 Therapeutics® and the G1 Therapeutics logo and COSELA® and the COSELA logo are trademarks of G1 Therapeutics, Inc. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "expect," "plan," "anticipate," "estimate," "intend" and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Forward-looking statements in this press release include, but are not limited to, the potential for trilaciclib to enhance long term immune surveillance by enhancing T cell function and the generation of certain memory T cells, the association between gene expression profiles demonstrated by the Phase 2 Mechanism of Action Trial results and the improved clinical outcome, the expectations for further Phase 2 Mechanism of Action Trial results to support the current observation of an increase in the ratio of CD8+ T cells to regulatory T cells (Tregs), that trilaciclib’s greatest effect is on longer term endpoints including OS rather than earlier efficacy measures such as pCR, ORR and PFS, and that the reason why trilaciclib’s greatest effect on longer term endpoints is because of its immune-mediated mechanism of action are based on the company’s expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties. Factors that may cause the company’s actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in the company’s filings with the U.S. Securities and Exchange Commission, including the "Risk Factors" sections contained therein and include, but are not limited to, the company’s dependence on the commercial success of COSELA (trilaciclib); the development and commercialization of new drug products is highly competitive; the company’s ability to complete clinical trials for, obtain approvals for and commercialize any of its product candidates; the company’s initial success in ongoing clinical trials may not be indicative of results obtained when these trials are completed or in later stage trials; the inherent uncertainties associated with developing new products or technologies and operating as a commercial-stage company; and market conditions. Except as required by law, the company assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available. G1 Therapeutics Contacts: Will RobertsVice President, Investor Relations & Corporate Communications919-907-1944 wroberts@g1therapeutics.com