Getting the Biology Right
Another new frontier in automation is an area of research that had been difficult-to-impossible to automate in the past: cell-based assays. Cell-based screening has a number of advantages over biochemical screens, the main one being that it is a close representation of the biology of the environment in which the final drug will be used. With older-generation automated systems using large robotic liquid-handling systems, it was difficult to model cellular biology within the assay. Now, a number of systems are coming online that incorporate more biologically appropriate assay conditions.
Odyssey Thera has developed a high-throughput platform that tracks subcellular protein complexes using a system of automated microscopes and unique cellular probes. According to the company, the strength of its platform lies in the combination of automation and systems biology, and the large number of molecules that comprise Odyssey’s database. The system is able to use image analysis and a proprietary IT infrastructure to process the assays at a rate of millions of wells per run, reports John Westwick, Ph.D., president and CEO.
“The majority of our day-to-day effort entails using the platform to look at test agents and candidates from our big pharma partners. We know what successful and failed or toxic drugs drugs look like. We can look at hundreds of thousands of drug candidates and flag those that might have safety issues.”
In addition to toxicology prescreening, the platform has great potential for drug repurposing and reindication, Dr. Westwick adds. By running known agents across the large panel of cellular assays, new therapeutic indications can be identified by comparing signatures to the pathway and systems biology information in the database. “We have been able to identify mechanistic signatures, and redraw many of the cellular signaling pathways,” he notes. “Most important, perhaps, are the connections we’ve identified between known pathways—in the long term that may be our most important contribution.”
Fabrus has a new take on some older technology—a way of expressing antibody Fab fragments in bacteria more efficiently. It has expanded on that method and adapted it to a system that makes antibody Fab production and screening a little more like small molecule screening. It’s a way to bridge or adapt biologics research to the more common paradigms and technologies that exist within drug discovery, the company reports. Using the system, Fabrus has created a library based on human antibody sequences, and which are individually addressed in 384-well plates.
Fabrus is using an automation solution called Piccolo from The Automation Partnership. This room-sized instrument enables it to express and purify up to 576 samples per week with high yields and an average of 50 ug of protein per sample, with just one operator.
Most antibody screening assays are based on binding rather than any functional activity of the antibody, and through a process of mutation and maturation they will produce a final antibody, and then begin functional studies. Fabrus has worked around that multistep process by using naïve antibodies, not raised to any specific antigen, and then screening them just like any small molecule screen with the goal of producing a therapeutic antibody.
It’s been traditionally difficult to conduct high-throughput screens under natural biological conditions such as physiological temperatures. For this reason, Bernhard Becker, a research assistant at Technical University in Munich (TU; portal.mytum.de), has been working on a high-content screening system based on living cells that is small enough to fit inside a temperature-controlled chamber.
The system is primarily intended for chemosensitivity testing, to determine the most effective medication for cancer patients. The system measures the metabolism and morphology of the cells through pH, pO2, and impedence values, supplemented by imaging.
Joachim Wiest, an engineer with Cellasys, which is working with TU on the prototype, explains that “the biggest problem to get these systems to run is to solve interdisciplinary problems—to get all this knowledge together. Maybe you can find a good engineer or biologist, but it’s hard to find a good bioengineer.”
An interesting wrinkle in the development of the system is that, although it includes microscopic images, these are technically not necessary to assess the morphology of cells. The impedence measurement gives information about morphology. However, the microscopy is an element that most physicians are not ready to part with when it comes to cell morphology, and it is a useful means of validation. “Most doctors are more used to seeing a microscopic image than a metabolic rate,” says Becker. “At the moment we have to use it. If you want to get the system in the hospitals, you will have to work with the doctors first.”