Use of Small Molecule Inhibitors to KLF10 for Modulation of T Regulatory Cells and Cancer Immunotherapy

Executive summary

The development of immunotherapies for cancer is rapidly increasing and expanding. The cancer immunotherapy market is expected to be worth over $300 billion by 2030.

However, a major obstacle for immunotherapies is regulatory T cells. Specifically, CD4+CD25+ T regulatory cells (T regs) suppress the immune response to maintain self-tolerance and are a significant obstacle for effective tumor immunosurveillance, vaccine-induced anti-tumor immune responses, and clearance of bacterial pathogens.

KLF10, a member of the Krüppel-like family of transcription factors (KLFs), has been shown to play a role in the conversion of CD4+CD25- T cells to CD4+CD25+ T cells (T regulatory cells).

Dr. Mark Feinberg from Brigham and Women’s Hospital has capitalized on this discovery and has identified three novel small molecule inhibitors that inhibit the binding of KLF10 to DNA, the expression of Foxp3 (crucial in the conversion of CD4+CD25- cells), and the conversion of CD4+CD25- cells into T regulatory cells.

The inhibition of KLF10 would improve a patient’s self-immunity against a tumor. A deficiency of KLF10 is also associated with improved bone density.

Value proposition

Cancer immunotherapy is a rapidly expanding market. This technology would enhance the efficacy of these novel immunotherapies by suppressing the regulatory side of the immune system. In the past, KLFs could not be targeted by small molecule inhibitors due to a lack of enzymatic activity. This technology offers a novel approach to targeting KLF10 via small molecule inhibitors, a quickly growing sector of the cancer immunotherapy market.

Team

Technology

Background and proof of concept

The three small molecule inhibitors were selected using computer-aided drug design (CADD) screens of chemical libraries. The small molecule compounds (#48, #48-15, #15-09) were shown in vitro and via electromobility gel shift assays to inhibit KLF10-DNA binding. The inventors also showed in vitro and with qPCR measurements that these compounds inhibit the expression of Foxp3 that is crucial in the conversion of CD4+CD25- T cells into CD4+CD25+ T cells.

Advantages and progress

Small molecule inhibitors may allow for “fine-tuning” T regulatory cells and the anti-tumor immune response without concerns of long-lasting effects from monoclonal antibody blockade that predispose to autoimmunity or other inflammatory conditions. Second-generation small molecules are being generated built on the discovery principles of the three small molecule inhibitors of the KLF10 protein-DNA interaction interface.

Mechanism

The inventors interrogated a “druggable” pocket in the second zinc-finger of KLF10 using CADD screens of chemical libraries. They found that the three small molecule inhibitors, #48, #48-15, and #15-09, had similar scaffolds and binding patterns. Each of these small molecules inhibited KLF10-DNA binding and transcriptional activity, the conversion of CD4+CD25− T cells to CD4+CD25+ T regulatory cells, and KLF10 target gene expression.