We first reported in DDW in 2003 on theemergence of automated patch clamp-ing (APC) as a higher throughput (HT)

alternative to traditional electrophysiologicalinvestigations made using manual patch clamp1. Inthe intervening period APC platforms haveemerged to play a pivotal role in ion channel drugdiscovery. APC technology more than any other,has opened up the field to wider investigation,made ion channels more accessible as drug targetsand facilitated the drive towards highest possibledata quality. APC systems have evolved consider-ably in recent years with second and third genera-tion platforms addressing both voltage and ligand-gated channels at HT and at higher seal resistanc-es2. This evolution has not been without casualtiesas one player (Cellectricon) working on a HT APCsystem (Dynaflow HT) has already changed focusand withdrawn from all direct product sales. Inlate 2013 only one commercial system (MolecularDevices IonWorks Barracuda Plus) could beregarded as offering true 384 parallel acquisitionof an entire 384-well planar PatchPlate™. The

decision to implement APC systems into primaryion channel screening has therefore been rathermuted to date as end-users seek to trade-off thepotential gains in throughput versus the chip priceper patched well, the seal resistance/data qualityrealised and level of walkaway automationachieved. All this could be set to change as twonew 384 APC systems (Nanion Syncropatch384PE and Sophion Qube) become available utilis-ing 384 patch amplifiers, enabling high qualitysimultaneous patch recordings from 384 wells andseamless integration into screening robots. It willbe interesting to see whether the increased choiceof 384 APC systems will intensify competition inthe market such that APC consumables (patchplates) pricing will be reduced to a point where384 systems can finally bridge the gap between pri-mary ion channel drug screening (where APC isused today by only a minority of labs) and second-ary screening/hit-to-lead follow-up (where APC isused today by the majority of labs).

In this article we review feedback from a recentmarket survey3 on the current use of automated

By Dr John Comley

Drug Discovery World Fall 2014 45

Electrophysiology

AUTOMATED PATCHCLAMPING finallyachieves high throughout!

Two new third-generation automated patch clamp (APC) systems capable ofhigh throughput processing (10,000 data points per eight-hour day) and fullrobotic integration have been recently launched. The resulting wider choice ofprimarily 384 APC systems has the potential to intensify competition in themarket for APC consumables (patch plates). Current patch plate consumablepricing still lags behind customer expectations. It remains to be seen if anyvendor will break ranks by significantly lowering its consumable price, therebyunlocking the broader exploitation of APC and finally facilitating cost-effectiveprimary ion channel screening of large libraries via patch clamping.

patch clamping in ion channel drug discovery labsand discuss what end-users are seeking in the new384 systems if they are to affect their future screen-ing activities. These findings are considered togeth-er with a vendor update on their latest APC offer-ings, and the increasing use of HT APC systems byservice providers.

Ion channel programmesSurvey respondents reported they were undertak-ing a median of three ion channel drug discoveryprogrammes in 2013 and expected the same num-ber in 2014. The primary drivers for initiating anew ion channel programme in a survey respon-dent’s organisation was the disease focus of com-pany. This was distantly followed by availability ofdruggable target; availability of suitable cell lines;and then customer request. Availability of suitablecompound library was the least important driver(Figure 1).

Use of APC technologies todayAPC technologies were most used today (2014) bysurvey respondents for assay development (76%using); followed by hits-to-leads (lead optimisa-tion) (68% using); and then secondary screeningand selectivity profiling (both 66% using). Justunder half of survey respondents were using APCtoday for primary screening. APC technologieswere least used today (2014) in basic research(41% using) and safety assessment (compliant)(only 25% using) (Figure 2).

Survey respondents reported that the mediancompound library size tested using APC today(2014) was: 1,000-5,000 for primary screening/HTS; <1,000 for secondary screening and all hit-to-lead follow-up; and <1,000 for early non-com-pliant hERG liability testing. Survey respondentsreported that the median number of APC wellsprocessed per year using APC today (2014) was:5,000-10,000 for primary screening/HTS; 1,000-5,000 for secondary screening and all hit-to-leadfollow-up; and 1,000-5,000 for early non-compli-ant hERG liability testing. From this data we canconclude that APC is not yet being widely used forthe screening of larger libraries (Table 1).

Survey respondents reported that the majority(79%) of their APC assays today (2014) involvedrecombinant cell lines. All other cell types had lessthan 5% use. iPSC-derived cardiomyocytes are cur-rently used in 3% of APC assays and iPSC-derivedneuronal cells in 2% of APC assays (Figure 3).

Based on the prevalence of available APC instru-ment platforms in survey respondents’ labs, the fol-lowing vendor share of the current APC installed

46 Drug Discovery World Fall 2014

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3%

5%

10%

10%

10%

11%

12%

13%

25%

0% 5% 10% 15% 20% 25% 30%

Availability of suitable compound library

Trends in the market

Availability of assays

Availability of suitable APC assays

New safety guidelines

Customer request

Availability of suitable cell lines

Availability of druggable target

Disease focus of company

% Responding

Figure 1: Primary drivers for initiating a new ion channel programme

© HTStec 2014

25%

41%

44%

49%

55%

66%

66%

68%

76%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Safety assessment (compliant)

Basic research

Target identification/validation

Primary screening/HTS

Safety assessment (non-compliant)

Selectivity profiling

Secondary screening

Hits-to-leads (lead optimisation)

Assay development

% Responding

Using

Not Using

Figure 2: Different areas using APC today (2014)

© HTStec 2014

1%

2%

2%

3%

3%

4%

6%

79%

0% 10% 20% 30% 40% 50% 60% 70% 80%

Primary cardiomyocytes

iPSC-derived neuronal cells

Cardiomyocyte cell lines

Primary neurons

iPSC-derived cardiomyocytes

Neuronal cell lines

Other

Recombinant cell lines

% Responding

Figure 3: Proportion of different cell types used inAPC assays today (2014)

© HTStec 2014

Drug discovery area

MEDIAN typical library size

screened

MEDIAN no. APC wells

screened/yearPrimary screening (HTS) 1K-5K 5K-10KSecondary screening and all hit-to-lead follow-up <1K 1K-5KEarly non-compliant hERG liability testing <1K 1K-5K

Table 1: Screening metrics in different drug discovery areas using an APC platform

base was estimated: 32% Molecular Devices; 32%Sophion; 25% Nanion; 8% Fluxion; and 3%Cytocentrics (Figure 4).

Future purchasing of APC platformsSurvey respondents chose the quality of the resultsas the factor which would most influence theirdecision to purchase a particular brand/model ofAPC platform. This was followed by throughput;cost per data point; and then cost of APC plat-form. Least influential factors were a turnkeysolution and use of fluoride-based Ringers solu-tion (Figure 5).

What prevents the greater use of APC consumablesThe factors that most prevent survey respondentsfrom making greater use of APC consumablestoday were too high cost of APC consumable priceand lack of projects (both equally chosen as mostimportant factors). These were followed by totalcost of running experiment; lack of suitable tar-gets; and then lack of personnel/expertise. Missingfeatures of the APC consumable and lack of rele-vant APC instruments had minimal effect on pre-venting survey respondents making greater use ofAPC consumables today (Figure 6).

Impact of the availability of 384-wellAPC screening platformsMost (32%) survey respondents predict the effectof the introduction of new 384-well APC screeningplatforms will be to increase the number of datapoints screened, but with similar (unchanged) con-sumable budgets. This was followed by initiateAPC screening at an earlier point in the drug dis-covery process (22% responding), and then nochanges in our screening activities expected andswitch primary screening to a direct APC assay for-mat (both with 19% responding). Only 5% of sur-vey respondents thought the introduction of new384-well APC screening platforms will result in anincrease in their ion channel screening consumablebudget (Figure 7).

Survey respondents reported that for the new384-well APC screening platforms the median pro-hibitive price point was $1 per APC data point. Incomparison, the median stimulative price pointwas $0.25 per APC data point. Survey respondentsreported that for the new 384-well APC screeningplatforms, the median prohibitive price point was$350-$450 per 384 patch plate. In comparison themedian stimulative price point was <$250 per 384patch plate (Table 2).

Drug Discovery World Fall 2014 47

Electrophysiology

Molecular Devices 32%

Sophion 32%

Nanion 25%

Fluxion 8%

Cytocentrics 3%

Figure 4: Estimated vendor share of current APC installed base (2014)

© HTStec 2014

0%

2%

3%

3%

5%

7%

8%

12%

12%

14%

17%

19%

24%

25%

27%

31%

32%

53%

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55%

Use of fluoride-basedRingers solutions

Turnkey solution

Seamless integration inrobotic liquid handlers

Auxiliary features

Ease of use

Degree of automation

Available assays

Analysis software

Pharmacology

Internal/organisational reasons

Consumable performance

System stability

Cost of consumable

Vendor support

Cost of APC platform

Cost per data point

Throughput

Quality of results

% Responding

Figure 5: Factors which would most influence thedecision to purchase an APC platform

© HTStec 2014

2%

3%

4%

6%

8%

10%

10%

12%

23%

23%

0% 5% 10% 15% 20% 25%

Lack of relevant APC instruments

Missing features of the APC consumable

Lack of access to ephys expertise

Lack of stability on APC platform

Lack of throughput capabilities

Lack of personnel/expertise

Lack of suitable targets

Total cost of running experiment

Lack of projects

Too high cost/price of APC consumable

% Responding

Figure 6: Factors preventing greater use of APC consumables

© HTStec 2014

Vendor updates of APC systemsThe Cytocentrics Bioscience (www.cytocentrics.com) CytoPatch™ is the new gold standard inpatch clamp. Cytocentrics has spent most of itsdevelopment history on increasing content rich-ness, data quality and assay flexibility by replacingMPC with a self-contained, integrated instrument –but without compromising the automation advan-tages or the manual flexibility. Today theCytoPatch™ gets used in routine-screening for avariety of cell lines or primary cells. Cell consump-tion per experiment can be reduced to as few as150 cells and Gigaseal patches are standard.CytoPatch’s superior perfusion system ranges fromultra-fast ligand gated ion channels (GluA2 at 3msapplication speed) to continuous compound appli-cation (TRPM4 with > 10 min for first cell reac-tion). Our primary cells customers are typicallyusing DRG neurons, cardiomyocyte cell lines orpatient derived iPSC for robust, operator-inde-pendent and reproducible experiments with volt-age clamp and current clamp. For CROs orPharma important features are dosage control andthe GLP compliant software. Both are fully sup-ported and aided with a clustered device strategy.You can operate up to 20 CytoPatch™ devices in anetwork; in a collaborative manner – as if it wereone – globally geared, locally operated. AgainCytocentrics’ focus is on user flexibility paired withscalability advantages for devices and also for con-sumables – choose between one, two or four chan-nel chips. All supported by an easy-to-learn, easy-to-use, but powerful and flexible software.Predefined drag-and-drop elements and hands-onoperation of the CytoPatch can be tailored andquickly trained at all skill levels, from student, labtechnician, PhD to principal scientist, or ondemand supported by remote access to our scien-tists. CytoPatch™ assay portfolio also allows forcomprehensive temperature control, intracellularperfusion or perforated patch, mechano-stimula-tion, lipid bilayers or single channel recordings. Inaddition, CytoPatch’s fully enclosed housing sup-ports light-sensitive cell analysis (Figure 8).

The Fluxion Bioscience (http://fluxionbio.com/)IonFlux HT (distributed by Molecular Devices) isan APC based on a unique microfluidic design thatcan, for high complexity assays, achieve the highestthroughput in ion channel recordings among allAPC systems. With most systems, the throughputbottleneck is the delivery of solutions (known aspipette waiting time). For assays that require a sin-gle data point site recording, higher throughput isdictated by an increase in recording channels;

48 Drug Discovery World Fall 2014

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3%

5%

19%

19%

22%

32%

0% 5% 10% 15% 20% 25% 30% 35%

Decrease the ion channel screening consumable budget, but screen similar number of data points

Increase our ion channel screening consumable budget

Switch primary screening to a direct APC assay format

No changes in our screening activities expected

Initiate APC screening at an earlier point in the drug discovery process

Increase the number of data points screened,but with similar consumable budget

% Responding

Figure 7: How new 384 APC platforms may affect screening activities

© HTStec 2014

Figure 8: In contrast to other planar patch clamp platforms, the unique CytocentricsCytoPatch™ Chip contains a real patch pipette that is surrounded by the Cytocentering™opening. The latter is used to position the cell on the patch pipette. By application of precisepressure protocols through this patch pipette, gigaseals and the whole-cell break through areobtained. The sealed cell is then continuously perfused with extracellular buffer or testcompound. This resembles the patch clamp process known from the manual patch clamp andresults in the highest quality of recordings known

however, with complex assays involving doubleagonists, desensitising ligand-gated channels, orallosteric modulation, flexibility in liquid exchangeis the key for higher throughput. The IonFlux HTuses unique in-plate microfluidics to achieve twokey features: rapid and flexible serial displacementof solutions and continuous flow. Both of these keyaspects allow the execution of very complex assaysinvolving multiple solution exchange. With 64independent recording amplifiers, the lack ofdependence on mechanical liquid handlers givesthe system the fastest parallel execution of com-pound application, allowing full assays to be asshort as 10 minutes, and up to 1,500 data pointsto be collected within the hour. Recently intro-duced enhancements in software married to nativecontinuous flow allow even higher flexibility insolution delivery, facilitating and accelerating com-plex channel-modulation assays requiring consis-tency and reproducibility of background ligand-activated recordings (Figure 9).

Molecular Devices (www.moldev.com) offers theIonWorks Barracuda system which is a 384-wellAutomated Patch Clamp system with patentedconsumable fluidics and Population Patch ClampTechnology. The system features a dedicatedamplifier and pipettor for each of the 384-wells, nomultiplexing is required. The system has the lowestper well running cost of any available system toallow the screening of customers’ small- to large-compound libraries up to several hundred thou-sand compounds. Pharmacological evaluation ofcompound potency is also routinely performed onthe system with the option of performing cross-well or within-a-well compound dose responsecurves. The advantage of cross-well dose responsecurves is that control and test wells are measuredsimultaneously. This eliminates potency artifactscaused by current rundown which many ion chan-nels (eg calcium channels) experience even on man-ual patch clamp rigs. The patented PopulationPatch Clamp technique (64-cells/well) is requiredto perform these cross-well pharmacological eval-uations. The advantage of within-a-well doseresponse curves is that they reduce running costsdramatically by reducing the consumable costdepending on the number of compounds added perwell. The fluidic chamber within the consumableprovides rapid exchange of fluidics not possiblewith an open-well design. This is required for themeasurement of fast-ligand gated channels toensure that little dilution of ligand occurs prior tothe ligand reaching the cell to avoid desensitisationof the target channel. The IonWorks Barracuda

Drug Discovery World Fall 2014 49

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Figure 9: Designed like a plate reader, The Fluxion Bioscience IonFlux HT’s unique shapegives it perfect adaptability for automated plate handlers, making it extremely suitable for HTcentres. With the use of industry-standard 384 plates, standard liquid handlers and pipettorscan be used to automate the plate preparation and delivery. Up to four IonFlux HT can bestacked for maximum performance and throughput

Figure 10: Molecular Devices’ IonWorks Barracuda system is a 384-well APC system withpatented consumable fluidics and Population Patch Clamp Technology

system is installed at dozens of customer sitesworldwide and offers the highest throughput andlowest running costs of any automated APC system(Figure 10).

In 2013, Nanion Technologies (www.nanion.de)started shipping the SyncroPatch 384/768PE, final-ly reaching a throughput in gigaseal patch clampmatching the requirements of ion channel highthroughput facilities with respect to hardwarerobustness, software integration and automateddata analysis. The SyncroPatch 384/768PE consistsof one or even two patch clamp modules, the Patch

50 Drug Discovery World Fall 2014

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Contact us for a demo & see for yourself!www.nanion.de

SyncroPatch 384/768PE:• >20,000 data points per day• 768 parallel giga-seal recordings• Seamless integration in HTS-environments• Modular approach

Patch Clamp Goes HTS

Figure 11The SyncroPatch 384/768PE is a patch clamp-based,HTS-compatible ion channel screening platform fromNanion, allowing for 384 or 768 parallel, giga-sealrecordings. The platform consists of a patch clampmodule, the Patch Engine (insert), integrated in a state-of-the-art liquid handling robot, here the Biomek FXfrom Beckman Coulter. The SyncroPatch 384/768PEgenerates >20,000 data points per day

Engine (PE), which are integrated in state-of-the-art liquid handling robots. Two modules can berun in parallel, enabling giga-seal recordings from768 individual cells in parallel. The hardware andsoftware design is open and fully accessible toHTS-robotics serving the platform with recordingplates, compounds and cells, thus permitting 24-hour operation. The SyncroPatch 384PE has beenvalidated with a broad range of cells, voltage- andligand-gated ion channels, allowing for screens ofchallenging ion channel targets and protocols. Thetime required to run a 384 plate is approximately15 minutes, including chip load and priming, celladdition, capturing and patching, a three concen-tration dose response curve with multiple controladditions. The assay development is straightfor-ward; cells performing well on other APC systemwill work on the SyncroPatch 384/768PE withoutmajor modifications. The SyncroPatch PatchEngine achieves extraordinarily high success rates,both in single hole and multi-hole mode.Additionally, stem cell-derived cardiomyocytes andneurons have proven to work very well on the plat-form. Experimental features such as temperaturecontrol and current clamp recordings are optionalon the SyncroPatch 384/768PE. The consumablesfor the Patch Engine are very competitively priced,so that large scale screens indeed become afford-able. With the SyncroPatch 384/768PE, it is thefirst time that patch clamp-based ion channelscreening is compatible with full primary screeningautomation, throughput and costs per data pointrequirements. Nanion now offers four APC instru-ments, ranging from one to 768 parallel, giga-sealrecordings, for comprehensive ion channel screen-ing and research (Figure 11).

Sophion (www.biolinscientific.com/sophion/) is aleader in the technology field of automated patchclamp (APC). The mission of Sophion is to aid andaccelerate the efforts of pharmaceutical companiesto discover ion channel modulators. SophionBioscience was founded in 2000 and in 2011 itbecame part of the Biolin Scientific family of com-panies. Sophion introduced the QPatch line ofproducts of fully automated patch clamp plat-forms in 2004. The medium throughput system,QPatch, can test up to 7,000 data points in 24hours. QPatch has become the primary APCinstrument for lead optimisation of drug candi-dates and for cardiac safety testing at both largepharmaceutical companies and smaller biotech-nology companies focused on ion channel discov-ery. With Biolin Scientific’s support it has devel-oped the next generation high-throughput system

Drug Discovery World Fall 2014 51

biol

insc

ient

ific.

com

/sop

hion

Qube is a turn-key HTS system, integrating hardware and software developed by Sophion experts

Qube is reliable pharmacology, simple and unattended system operation with competent support 24/7

Advanced Ion Channel Screening. Preferred by experts

Electrophysiology

called Sophion Qube. The Qube is a 384-channelautomatic patch clamp system that can deliver ionchannel data up to 30,000 compounds per 24-hour data when integrated into an automatedscreening line. The Qube will permit companies tostart the ion channel discovery process with patchclamp, the gold standard for ion channel measure-ment rather than indirect technologies. Qube isavailable as a stand-alone system with up to fourhours’ unattended operations or as a customisedsolution integrated into a company’s automatedscreening process (Figure 12).

Updates from service providers using HT APC systemsThe ability to detect and characterise the func-tional properties of subtype-selective compoundsis an important goal of cell-based assays in drugdiscovery. Nicotinic acetylcholine receptors(nAChRs) are therapeutic targets for a variety ofindications including cognition impairment,Parkinson’s disease, depression, substance addic-tion and inflammatory diseases, and thus areimportant targets in pharmaceutical research. Thereceptors belong to a family of ionotropic recep-tors that function as acetylcholine-activatedcationic channels, amenable to detailed, but low-throughput analysis by conventional voltageclamp. APC systems offer the possibility of highthroughput, high quality ion channel screeningand profiling for drug discovery. ChanTest(www.chantest.com) has optimised humannAChR-expressing cell lines for IonWorksBarracuda assays in 384-well, population-patchformat to enable the rapid identification of com-pounds with selective nicotine receptor subtypemodulation properties. The assays are capable ofscreening thousands of compounds to facilitateidentification of actives and characterise theirreceptor subtype activity (ie, agonist, antagonist,or modulatory) in a high-throughput mode.ChanTest now offers validated assays for neu-ronal nAChRs, including �3�4, �7, �4�2, and�3�4�5 cell lines (�6* cell line is in develop-ment), and provides the cell lines as researchproducts to support extramural projects. Figure13 illustrates representative results from a screenconducted for identification of positive allostericmodulators of �7 receptors.

Essen Bioscience (www.essenbio.com) is a private-ly held company specialising in cell-based assays.As inventors of two paradigm shifting ion channelassay technologies, IonWorks and FLIPR, it has adeep understanding of the biological and technical

52 Drug Discovery World Fall 2014

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Figure 13: Single-point screen of a library of FDA-approved drugs for positive allostericmodulators undertaken by ChanTest. 794 drugs were tested at a single concentration (60µM,1 replicate/concentration), in IonWorks Barracuda (population patch mode). Each drug wasco-administered with nicotine at the EC20 concentration and peak currents were measured.Percent potentiation was calculated relative to control wells treated with nicotine only. Sevencompounds were found to increase peak current by more than two-fold (100-500% increase)compared to control. Of these, five compounds behaved as positive allosteric modulators (iehad no effect in the absence of nicotine). The other two compounds showed agonist activityin other experiments

Figure 12: Sophion Qube enables high throughput, automated patch clamp based screeningof compounds against ion channel targets

requirements for constructing relevant and transla-tional ion channel assays. Its Discovery Servicescontract research division integrates cutting edgemolecular biology, gene expression, electrophysiol-ogy (automated, manual patch clamp) and fluores-cence (eg Ca2+, Tl+ detection) methods to config-ure custom reagents, assays and integrated in vitroworkflows for our clients. Managed and staffed byhighly experienced ion channel drug discoverers,and with laboratories both in the US and UK, thisprovides a unique ion channel problem solvingresource. Essen’s specialty is automated electro-physiology which it has been carrying out since2002. With five IonWorks platforms worldwide(Quattro, Barracuda), it has the capacity to con-duct large electrophysiology screens (up to 50,000samples) with high quality and fast turnaround forboth voltage and ligand-gated targets. Mostrecently it has assembled and validated a full panelof assays for hNaV channels (1.1-1.8) which isamenable to small molecule and antibody discov-ery strategies alike. Essen’s higher throughputapproach couples the precision and relevance oftranslational electrophysiology protocols with anaffordability that permits early and wider scaletesting (eg for cardiac safety assays such as hERGand hNaV1.5). It has also adopted a multitude ofbusiness relationships to meet the needs of itsclients ranging from fee-for-service to collabora-tions involving structured milestone payments(Figure 14).

Pain, cognitive health and cardiovascular diseaseare among the many therapeutic areas in which ionchannels are considered valuable drug targets. Atthe same time, many ion channels, including hERG,have also been implicated as being responsible forinducing adverse side-effects. As such, the develop-ment of drugs targeting ion channels requires a bal-ance of efficacy and liability screening. EurofinsDiscovery Services (www.eurofins.com/discovery-services), as a supplier of key screening reagentsand related services, provides two options to sup-port the future wave of ion channel directed thera-peutics. Eurofins Discovery Services developed aportfolio of PrecisION® cell lines for more than 60different human ion channels covering some of themost prominent therapeutic targets for pain (eg,hNav 1.7, TRPA1, etc), cognition (eg, nAChR 7�,GABAA �5�3�2, etc) and cardiac liability (hERG,Nav1.3, etc) with the expertise to build companionortholog cell lines to evaluate the impact of speciesdifferences for in vivo efficacy studies. These celllines were created to specifically use on automatedelectrophysiological platforms to facilitate higher

Drug Discovery World Fall 2014 53

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Figure 14: High throughput ion channel discovery services at Essen Bioscience usingIonWorks APC platforms

Figure 15: Potentiating the response to acetylcholine by increasing concentrations ofPNU120596, an allosteric modulator, using PrecisION® nAChR �7 cell line from EurofinsDiscovery Services on IonFlux® HT platform

throughput screening. IonFlux™ HT is a recentaddition to the automated electrophysiology plat-forms used in IonChannelProfiler™ services whichalso includes IonWorks® Quattro™, PatchXpress®and QPatch instruments. With its ability to contin-uously record an ensemble of whole cell patches,this latest device is ideal for screening agonist,antagonist or allosteric modulators for emergingtherapeutic targets such as nAChR �7, a fast-actingligand-gated ion channel. Eurofins DiscoveryServices can quickly provide the necessary follow-

up work to verify compound activity in manualpatch clamp studies, provide related compoundselectivity by performing counter screens on relatedfamily members and assess cardiac liability throughCardiacProfiler™ service (Figure 15).

Evotec (www.evotec.com) combines PhD-levelChemists and Biologists experienced in ion channeldrug discovery with manual patch clamp and mul-tiple automated patch clamp platforms to providecollaborative HTS and in vitro pharmacology serv-ices that successfully identify and optimise newchemical matter at ion channel targets. TwoIonWorks® Quattro 384-well instruments providethe highest throughput available for many voltage-gated channels and select ligand-gated examples.Two QPatch 48 HTX instruments provide 48-well-based Gigaohm seal quality and liquidics that areutilised to confirm fluorescence-based HTS hitsand provide the high quality data necessary for hitto lead and lead optimisation support, even for themost demanding ion channel targets, such as TRPchannels. An additional Gigaohm seal platform,the Patchliner®, offers 16-well throughput.Multiple manual patch clamp rigs support spot-checking of the potency values obtained on theautomated systems, assay development anddetailed mechanistic studies, in addition to poten-cy determinations on primary cells and tissuesources. Our careful assay development and ongo-ing quality control minimise the use of costly patchplate consumables while deriving potency data thatallow rapid and optimal SAR decision making bymedicinal chemists. In addition to profiling at thetarget, assays for structurally-related channels ofside-effect concern and cardiac ion channels areprovided on the automated platforms. Evotec’sexperience with progressing multiple ion channelprojects through all stages of drug discovery toclinical candidates ensures a collaborative relation-ship where these technologies are designed, imple-mented, and used to support team decision-makingin fully-customised workflows that ensure success(Figure 16).

DiscussionTable 3 lists the latest APC offerings reviewed inthis article and attempts to compare them withrespect to several features of interest to potentialcustomers including their relative costs, through-out potential and seal resistance. The first point tomake is that all systems (only to a lesser extentCytocentrics) are now able to exploit the time andcost savings associated with fully robotic screen-ing automation. Only Molecular Devices, Nanion

54 Drug Discovery World Fall 2014

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Figure 16: One of the two QPatch 48 HTX instruments at Evotec’s facilities

and Sophion are 384-dispenser compatible sys-tems and as such are more easily compared. Thesethree systems now enable access to higherthroughput (HT) APC, up to and beyond what hasbeen perceived as the 10,000 data points per eight-hour day threshold needed for meaningful drugdiscovery and to consider deployment in primaryscreening. Further enhancements on throughputcan be obtained by integrating two modules of theNanion SyncroPatch 384 PE into one liquid han-dling robot enabling 768 recording wells to bemeasured simultaneously giving a throughput of20,000 data points per eight-hour day. TheFluxion IonFlux HT can also deliver, under certainconditions, up to 10,000 data points per eight-hour day and when four units, of these bench-topplate-reader sized boxes, are arrayed around a liq-uid handler can achieve up to 40,000 data pointsper eight-hour day. Of the five APC systems dis-cussed, the Molecular Devices IonWorksBarracuda Plus is noteworthy in that it operates ata lower seal resistance, although MolecularDevices has demonstrated that the robustness andreproducibility offered by its patented PopulationPatch Clamp™ (PPC) more than compensates forthis perceived limitation. However, electrophysiol-ogy ‘purists’ who insist on a gigaseal in an APCsystem are now well catered for in the alternativeofferings. Although the systems now availableclearly enable access to higher throughput APC, it

can be seen that none yet offers really ‘stimulative’consumable pricing (ie as defined in the survey asenhancing use and widening APC adoption – seeTable 2). It should be stated that our analysisassumes a data point is based on a single test perwell, which is not the way some manufacturersprefer to promote their systems or how some end-users may actually use their systems. It is difficultto pin vendors down to a system price, and theactual price paid frequently may vary geographi-cally or is subject to local sales team pricing/dis-counts, but it is clear that to access an APC systemenabling HT you will need a budget of at least$500,000. The parameters mentioned above andlisted in Table 3 are not the only basis on whichAPC systems can be compared or evaluated, forexample we have not discussed the perfusioncapability where the minimum exchange time orminimum exposure time of ligand addition is veryimportant; whether the internal fluidics enableexchange during an experiment; what temperaturecontrol is offered during recordings; what minimal

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Pricepoints*

Price per 384 APC data point

Price per 384 APC patch plate

MEDIAN prohibitive pricepoint $1.00 $350-$450MEDIAN stimulative pricepoint $0.25 <$250* Prohibitive pricepoint – limits use to certain applications and inhibits adoption * Stimulative pricepoint – enhances use and widens adoption

Table 2: Price points for screening with new 384 APC platforms

Table 3: Comparison of APC offerings discussed in the article

APC SYSTEM/PARAMETER Cytocentrics CytoPatch

Fluxion IonFlux HT

Molecular Devices IonWorks Barracuda

Plus

Nanion SyncroPatch

384/768PE

Sophion Qube

No. of Measurement Wells/Consumable Plate: 4 64 384 384 384No. of Measurement Wells Processed Simultaneously: (Amplifiers Per Instrument)

4 64 384 384 or 768 384

Consumable has Integrated Electrodes: NO NO NO NO YESAverage Consumable Plate Cost: ($ USD) $10 $130 $175 ($250)c <$200 $437Cost Per Data Point Assuming Single Test/Well: ($ USD)

$2.50 $2.00 $0.46 ($0.65)c <$0.60 $1.20g

Data Points/8h Day Assuming Single Tests/Well: ~100 1,536a 8,800 10,000 or 20,000 10,000Typical Seal Resistance of Patch: (GigaOhms) 5 Gohm plus 0.8 - 5 Gohmb 150 Mohm 1-5 Gogm 0.8-1.2 Gohmh

Need for Seal Enhancer: NO NO NO YESe YESh

Flow Channel in Consumable: YES YES YESd NO YESApproximate System Price Range: ($ USD) $85K - $156K $275K-$285K $390K - $650K $499K(384PE) -

$748K(768PE)f$750K - $800K

Vendor's Comments On Their Offering: Cardiomyocyte APD, GLP, late sodium,

neurons, fast LGIC, temperature control

Industry leading flexibility and

performance in high throughput patch

clamp assays

Low running costs make this the choice

for screening ion channel libraries

Modular, scalable gigaseal platform, fully integratable

into pre-existing HTS-automation

environments

A complete turn-key HTS system: one

reliable platform, one reliable supplier

Footnotes:a based on 3 assays per hour each at 10 minutes running and 10 minutes prepb in single cell modec single hole plate (population patch clamp plate)d multiple patents issued on flow through designe recommendedf systems requires a liquid handling workstationg assumes 95% success rateh internal fluoride will improve seal

cell consumption is required per experiment; andwhether the system is fully GLP compliant. Theimportance of these depends on the ion channelunder investigation, the application area and otherend-user specific requirements.

The newer HT APC systems also allow fee-for-service providers such as ChanTest, Essen, Eurofinsand Evotec the possibility to now offer cost-effec-tive high quality outsourced ion channel screeningand profiling for drug discovery. HT APC systemnow gives access to large electrophysiologicalscreens with faster turnaround for both voltageand ligand-gated targets, with high seal qualitymaintained. Some service providers (ChanTest,Eurofins) and APC vendors (Cytocentrics,Sophion) also specialise in developing and offeringcommercially a portfolio of cell lines and assaysspecifically adapted and validated for use on HTAPC systems.

In conclusion, there has never been a moreopportune time to access high quality HT APC sys-tems, with a range of alternative systems and con-figurations now launched. Patch plate consumablepricing still currently lags behind customer expec-tations. It remains to be seen if any vendor willbreak ranks by significantly lowering its currentconsumable price, to really open up the widerexploitation of APC. DDW

Dr John Comley is Managing Director of HTStecLimited an independent market research consul-tancy whose focus is on assisting clients deliveringnovel enabling platform technologies (liquid han-dling, laboratory automation, detection instrumen-tation; assay methodologies and reagent offerings)to drug discovery and the life sciences. Since its for-mation 10 years ago HTStec has published morethan 100 market reports on enabling technologiesand Dr Comley has authored 50 review articles inDrug Discovery World. Please contactinfo@htstec.com for more information aboutHTStec reports.

References1 Comley, J. (2003) PATCHERSvs. SCREENERS – divergentopinion on high throughputelectro-physiology! DDW 4(4): 47-57.2 Comley, J. (2011) 8 Years ofSurveying Ion ChannelScreening – Has AnythingChanged? DDW 12(4): 45-62.3 Automated Patch ClampingTrends 2014, published byHTStec Limited, Cambridge,UK, April 2014.

56 Drug Discovery World Fall 2014

Electrophysiology