University of Wisconsin

Goal: Determine if targeting SLC16A14 could be a useful treatment approach for FLC.

Principal Investigator: Sean Ronnekleiv-Kelly, MD

Grant length: Two years

Study overview: Recently, Dr. Ronnekleiv-Kelly used sophisticated genetic engineering to create a highly promising mouse model of FLC and other cancers driven by the DNAJB1-PRKACA (DP) gene fusion. Dr. Ronnekleiv-Kelly’s first goal in this new study will be to characterize the progression of DP-driven cancers in the new model. This will help pinpoint the direct actions of the DP oncogene that are most critical to the development of FLC. In turn, these studies may uncover potential targets for new therapies.

The project’s second aim is to utilize the mouse model to determine the function of a specific gene, SLC16A14 (also known as MCT14), that has previously been identified as playing a critical role in FLC. Studies in Praveen Sethupathy’s lab at Cornell University revealed that this gene is highly expressed in FLC cells, at levels far above the expression in other human cancers.

SLC16A14 is a member of a transporter family of proteins that shuttle specific metabolites in and out of cells across the cell membrane, or across the membranes of organelles such as mitochondria, the “energy powerhouses” of the cell. Some SLC16 family members transport simple molecules such as glucose or related sugars or amino acids. However, the metabolites transported by the SLC16A14 protein have not yet been identified.

This study aims to determine how SLC16A14 is linked to the metabolic changes and survival of FLC cancer cells. Determining the exact function of this protein will help determine if an inhibitor of SLC16A14 could be a valuable therapeutic for FLC.

Goal: Determine if targeting CDK7 could be a useful treatment approach for FLC.

Principal Investigator: Sean Ronnekleiv-Kelly, MD

Grant length: Two years, plus extension

Study overview: Unregulated proliferation of cells is a hallmark of cancer. In other words, cancer cells continue to divide and increase in number when normal cells would stop dividing. A family of 20 proteins known as cyclin-dependent kinases (CDKs) play key roles in the regulation of cell division and other fundamental cellular processes. While CDKs are found in both normal and cancer cells, they are frequently present at elevated levels in cancers and may promote uncontrolled cell proliferation. A particular CDK, CDK7, has been associated with rapid progression and poor prognosis of various cancers. CDK7 acts as a gatekeeper for cell division, and also regulates gene expression. For these reasons, it has become an attractive potential anticancer drug target.

Dr. Ronnekleiv-Kelly observed that CDK7 is present at significantly higher levels in FLC cells than in normal liver cells. Furthermore, collaborative studies indicate that CDK7 is required for the expression of certain genes that become “locked on” at high levels in FLC tumor cells due to the fusion protein that is found in virtually every case of FLC. Thus, CDK7 appears to be a element in the pathway that drives the transformation of normal liver cells into FLC cells.

The principal goal of the proposed work is to determine whether a drug that blocks the action of CDK7 has potential value to treat FLC. Specifically, the investigators will test the hypothesis that an inhibitor of CDK7’s protein kinase activity will prevent the production of crucial “downstream” proteins that are “turned on” by FLC’s fusion protein, thereby halting the proliferation of the cancer cells.

Syros Pharmaceuticals, Inc. (Cambridge, MA) has developed a selective inhibitor of CDK7, SY-5609, that already has advanced into clinical trials in cancer patients. Preliminary data shows encouraging activity of SY-5609 against FLC cells. The study team will examine effects of CDK7 inhibition in several FLC cell model systems, PDX models, and slice cultures prepared from fresh human FLC tumors. They also will also work to understand the role of CDK7 in controlling the biochemical pathways that underlie the growth of FLC tumors.

If the results of this study are promising, they could set the stage for a clinical trial of CDK7 inhibition, alone or in combination with other drugs, in FLC patients.

Goal: Knock-out gene targets in a mouse model of FLC to identify potentially effective drug combinations for patients with advanced FLC

Principal Investigator: Sean Ronnekleiv-Kelly, MD

Grant length: One year

Study overview: This study will apply an innovative gene-editing based technology (genome-wide CRISPR knockout screen) on a mouse cellular model to screen all possible cancer targets (i.e., all genes) coupled with promising drugs to precisely identify the most lethal drug combinations in FLC. This knowledge will enable discovery of new and effective combined drug treatments for FLC that can overcome the cancer cell adaptive mechanism, and work cooperatively to maximize the tumor-killing effect.

The rationale is threefold. First, combination drug therapy is requisite for treatment resistant cancers like FLC, yet identifying optimal therapeutic combinations has been exceedingly difficult with existing methods. Second, genome-wide CRISPR screens knockout each of the ~20,600 protein coding genes in the genome (one gene per cancer cell) to identify specific genes associated with cancer cell lethality. Remarkably, this unique approach can couple each possible target (i.e. entire genome) with concurrent promising drug treatment (i.e. a core ‘backbone’ drug) to precisely reveal clinically relevant multi-drug therapy for FLC. Third, this innovative approach could identify and exploit the essential pathways by which the DNAJB1-PRKACA driver gene mutation promotes FLC aggressiveness and treatment resistance.

In future studies, any novel drug treatments identified will be tested in pre-clinical animal models meant to closely mimic human FLC, followed by evaluation in patients with this deadly cancer.