Znomics and the University of Utah’s Huntsman Cancer Institute last week said they plan to co-develop pre-clinical compounds for T-cell leukemia, autoimmune diseases, inflammation, and complications from organ transplantation using a zebrafish T-cell assay developed at HCI.
Zebrafish platforms, such as that of Znomics, can be used as alternatives to cell-based assays in situations where appropriate cells are difficult to work with, because zebrafish are inexpensive, easy to image, and develop rapidly.
Under the terms of the one-year collaboration, HCI will work with Znomics researchers to develop proprietary T-cell disease assays in the zebrafish. Researchers in the lab of Nikolaus Trede will use the assays to screen the university’s 250,000-compound library with the aim of identifying leads for further testing.
Portland, Ore.-based Znomics will provide an undisclosed amount of funding to HCI in exchange for an exclusive option to license any promising small molecules or lead compounds and all related intellectual property discovered during the collaboration.
Znomics was interested in HCI’s zebrafish screen, with which “we started to look for anti-leukemic compounds that would act like [the chemotherapeutic agent] dexamethasone,” but with fewer adverse events, Trede, a pediatric oncologist, told CBA News this week.
He said that he and his group had earlier been able to demonstrate that they can take a T-cell-specific transgenic cell line they generated called LCK-GFP, and “if one transfects them into the zebrafish larvae, at five days or six days, under fluorescent light, one can actually see the thymus glow green, from all the T-cells that have arrived there and are developing in the thymus.”
Within two days, dexamethasone added to the water had killed all the T-cells, said Trede. “That is also what happens to humans and mice when they are treated with dexamethasone, which is what commonly occurs with kids with leukemia. Of course, the thymus would shrink, because all the T-cells would be killed, and it would also kill the leukemic cells,” Trede said.
“In 96-well plates, we identified a number of compounds that would kill T-cells, and the nice thing now is that, compared to cell culture, you can immediately evaluate toxic effects on the whole vertebrate organism” because at five days zebrafish have a completely developed central nervous system, heart, liver, kidneys, and other organs, he said.
“At the same time, you can determine if the compound is orally available or if it is excreted by the kidney, so its a much more biologically relevant model compared to cell culture,” said Trede.
The investigators then tested active compounds from a chemical library licensed from San Diego-based contract research organization ChemBridge on human T-cell leukemia lines, and unrelated cell lines such as kidney and B-cells. So far they have identified at least one promising compound that kills the Jurkat T-cell line but spares normal cell lines, and have determined the compound’s pharmacokinetics.
“In 96-well plates, we identified a number of compounds that would kill T-cells, and the nice thing now is that, compared to cell culture, you can immediately evaluate toxic effects on the whole vertebrate organism.”
However, Znomics is more interested in a library comprising 250,000 synthetic and natural compounds bought by the University of Utah, Trede said.
“We will go through the library and hope that we find compounds with antitumor activity,” he said. “We will also develop a new screen, because we cannot use a luciferase reporter, due to patent issues. So we will find another way to image the gene expression.”
Znomics and HCI do not have a completely established assay yet. “That is why we said, ‘OK, let’s agree on one year, and see how it goes,’” said Trede. He added that he feels both parties would be amenable to continuing the collaboration. ”However, if we run into lots of road blocks, then maybe we’ll agree that it was a good try, but not the best way to invest Znomics’ money.”
Once the candidate compounds that have been identified are ready to enter the clinic, Znomics will likely partner with a pharmaceutical company, Kerry Rea, Znomics’ CFO, told CBA News. At that point, Znomics will likely outlicense the compounds to the pharma company or possibly be acquired outright.
The rights to Trede’s T-cell assays represent another notch on Znomics’ belt in the area of genetically engineered zebrafish models for drug screening. The company has developed a proprietary library dubbed ZeneMark, comprising more than 11,000 strains of zebrafish, which it created through a gene-modification technology known as retroviral insertional mutagenesis.
The library, which is stored in the form of sperm aliquots, represents roughly half of all known zebrafish genes, and the company plans to add enough additional strains to represent 80 percent to 90 percent of the zebrafish genome (see CBA News, 11/30/07).
Znomics is one of a growing number of companies using zebrafish as the basis for their drug discovery platform or services. Much of the mammalian genome is conserved between zebrafish and man. In addition, zebrafish are inexpensive, easy to image, and develop rapidly.
However, zebrafish may be better suited for certain types of assays that use cells which are difficult to work with — T-cells, for example.
As part of the collaboration, Trede has joined Znomics’ scientific advisory board. Znomics said it wanted to work with Trede’s group because “we try to keep tabs on what is going on in the zebrafish research community … [and Trede] is an expert on the zebrafish/human immune system … and had developed a T-cell assay that responded to some compounds he screened,” Znomics CEO Rich Sessions told CBA News in an interview this week.
He said that part of Znomics’ business plan is to develop lead compounds for obesity and diabetes, cancer, and neurodegeneration, and since “we had an interest in going into the cancer field [we] felt that Trede’s work was well worth considering.”
There’s another reason: David Ransom, Znomics’ director of genetics and functional genomics, had been a postdoc with Trede in the lab of zebrafish expert Len Zon at Children’s Hospital Boston.
“We began talking with Trede and became even more impressed with his technology and the resources at the University of Utah and HCI,” said Sessions.
“Trede recognized that with our ZeneMark library of knockout mutants, we had some capabilities for further assay development, and we were gearing up for doing our own internal drug-discovery work for compound screening,” he added.