It has been estimated that there are 10 to the 60 (one followed by 60 zeros) drug combinations covering chemicals, genomes, proteins, peptides and natural compounds that could be screened in an effort to find optimal and even personalised treatments for diseases. It is a fantastically large number and failure rate is high.
There is an important and unmet need for new medicines that can be mediated by the use of ultra-high-throughput microfluidic screening. In drug discovery, pharmaceutical companies screen hundreds of thousands of possible drug candidates against disease models.
However, some 95% of new drugs fail during development, with many failures attributed to efficacy and safety issues as the industry currently does not have the capability to screen every possible drug candidate, concentration or vary the drug efficacy safety tests due to sheer numbers.
In addition, the average cost to launch for a successful new drug can often exceed $2.5 billion and preclinical drug development is responsible for about 30% of the cost. High-throughput screening (HTS) is required to screening vast numbers of drug and drug combinations, as their effects on cells are difficult to predict. As a result, the testing of such drugs becomes an engineering issue.
HTS assays are used for screening huge drug-candidate libraries, including combinatorial chemistry, genomics, protein, peptide libraries and natural novel drug compounds. It has been estimated that the actual number of these possible drug candidates could be 1 novemdecillion (that’s 1 with 60 zeros).
Current approaches to HTS employ microplates with densities ranging from 96-1536 wells/plate, and reaction volumes ranging from 1mL to 1µL. The primary concerns with existing technology are the reagent costs and limited throughput.
That is why pharmaceutical companies both large and small are interested in cost-effective, high-throughput screening (HTS), particularly as preclinical development accounts for 40% of the typical cost of bringing a new drug to market.
Shannon-based Hooke Bio is leveraging the expertise of its multifunctional team to produce the first prototypes of a so-called Enigma HTS platform, which aims to use 3D cell cultures to generate more reliable data than current drug screening technologies at higher throughput than existing systems on the market.
The Enigma device is an ultra-high throughput, cell-screening platform that utilises multiple parallel lines to test combinations of cells and drugs using droplet microfluidic technology. The unexploited power of microfluidics lies in the counter-intuitive behaviour of fluids on the microscale.
The Hooke Bio design allows picking of aqueous droplets on the nanolitre scale from reservoir wells. Each well contains a different component, e.g. cells, drugs, reagents and droplets, which can be comprised of multiple different wells depending on the experiment being conducted. The tiny droplets are separated from each other by an immiscible carrier fluid, allowing each droplet to serve as an isolated reaction container.
Enigma is a fully automated system requiring minimal human interaction. The general operation sequence involves loading the cells and drugs into the test reservoir wells, picking various droplet combinations, incubating the droplets containing cells and drugs/drug combinations, and subsequently analysing the incubated droplets using the detection method of choice.
Microdroplet-based HTS therefore has the potential to reduce assay volumes, increase throughput and eliminate the need for liquid handling robots, all of which result in significant savings. Costings analysis shows that the throughput for the initial Enigma platform will be 16x that of current systems, capex for the platform will be 3x-4x less and the consumables costs will be 35x less than existing systems.
The name Enigma is inspired by the wartime rotor-cipher coding machine used during World War II. As Enigma is designed as an annular device, it is particularly suited to screening for suitable drug combinations against various cell lines. Enigma is particularly beneficial to smaller drug-screening companies or academic research groups, as it is a low-cost instrument that would allow them to enter the screening market.
As with any start-up business, initial costs have to be watched carefully before there is an income stream from sales. To this end, one measure that the firm has taken in the machine shop producing the stainless steel and aluminium components for prototype Enigma systems has been to purchase a German-built Hermle C 250 5-axis, vertical-spindle machining centre (VMC) through sole UK, Ireland and Middle East agent Kingsbury.
Hooke Bio's R&D engineer Shane Devitt explains: "We wanted a five-axis machine to produce components in one hit rather than two, as we need to hold tolerances down to ± 5 microns and that is difficult if a part has to be reclamped.
"Even with a drilled hole, where the accuracy of the diameter is defined by the cutter rather than the machine, it can have a slight offset if it has to be drilled from either side to meet in the middle and that causes a dramatic alteration to fluid flow.
"Unlike when early prototypes were being made at the University of Limerick on a three-axis VMC of another make, work is now automatically repositioned in-cycle using the rotary axes of the Hermle. It allows us to hold the accuracies we need and there is no tolerance build-up."
Engineering manager Daniel Murphy added, "We moved into our new premises on the Smithstown Industrial Estate in Shannon in April 2019 and the Hermle arrived soon after. We need to make around 40 different parts for an Enigma prototype platform, half of which are rotational and would normally be produced on a lathe.
"To avoid the expense of investing in a turning centre at this early stage, we make all components on the VMC, despite it not having a torque table and integral turning capability, as that also would have cost more.
"Round components are produced by circular interpolation milling and the rigidity of the Hermle ensures that all features are within tolerance, especially as parts do not have to be transferred from a lathe to the VMC for prismatic machining."
Hooke Bio's choice of a trunnion-type five-axis VMC rather than one with a B-axis spindle or knuckle-type table swivel was down to the ability of the trunnion design to hold tighter tolerances. The C 250 was selected following a visit to Kingsbury in Gosport and a trip to Hermle's production plant in Gosheim, southern Germany, where the medical company's engineers were impressed by machine demonstrations and the build process.
Coincidentally, corroboration of their machine selection came during a visit to the Shannon facility by a sales representative from cutting tool supplier Iscar, who mentioned that 10 of the same model of VMC are in use in their factory in Israel.
In an online paper published on Hooke Bio's website (www.engineersjournal.ie/2017/10/10/enigma-irish-biotech-develops-new-drug-screening-system), written by executive chair Prof Mark Davies, professor of engineering science at the University of Limerick, chief operating officer Dr Finola Cliffe and a PhD student at the University of Limerick, Anne O’Sullivan, the point is made that HTS is essential for screening vast numbers of drugs and drug combinations to assay their effects on cells, which are difficult to predict.
As a result, testing of such drugs becomes not so much a medical issue as an engineering project, which Hermle and Kingsbury are successfully helping the biotech company to undertake.
