Over the years, numerous hospital and reference laboratories have struggled with the concepts of validation for laboratory-developed tests (LDTs), specifically for cell-based assays. These tests are not developed by manufacturers, but independently developed in each lab. While publications and guidelines for test validation from organizations such as CLSI and ICSH (International Council for Standardization in Haematology) exist, there are few peer reviewed publications addressing cell based assays using fluorescence measurement.  In addition, under the urging of laboratory certification bodies, such as the American College of Pathologists, the U.S. Food and Drug Administration (FDA) is currently reviewing its role in oversight and regulation of LDTs.  FDA has indicated a probable draft guideline related to LDTs will be released this fall, but it is likely that the FDA will have more oversight in their development and validation.  Whether this would be direct oversight by an already over-burdened FDA staff or delegation to a third party in some type of "deemed status" roles remains to be seen.  Meanwhile no scientific, evidence based guidelines exist addressing how best to validate the performance of a cell based assay using fluorescence as the unit of quantitation.  ICSH and ICCS intend to rectify this situation based upon the input and volunteered effort of international experts in the field.

Meanwhile in the interim, FDA has released a 1 June 2011 draft guideline clarifying the proper labeling of "Research Use Only" (RUO) and "Investigational Use Only" (IUO) reagents.  Aside from reiterating previous definitions for such labeling of products, not yet having been either cleared or approved by FDA through their 510(k) or PMA review processes as a true "in vitro diagnostic device" (IVD) in the U.S., the guideline highlights some policy interpretations that will definitely affect availability to clinical cytometry laboratories.  For example, the document includes statements such as "At this time, FDA intends to exercise enforcement discretion with respect to persons who manufacture, propagate, compound, or process imported IVD products intended solely for research use." and " If a manufacturer learns that a laboratory to which it sells its RUO-labeled IVD product is using it in clinical diagnosis, it should halt such sales or comply with FDA requirements for IVD products, including pre-market review requirements, if applicable. FDA fully supports the use of IVD products labeled RUO for research purposes, but since these products may not be manufactured in accordance with current Good Manufacturing Practice (cGMP) and their performance characteristics have not been established, we believe they present a serious potential risk to the public health when used in clinical laboratories to generate tests results intended for patient management."  As many RUO products can serve as components of LDT assays that are in clinical use, such enforcement to restrict imported RUO products to clinical laboratories will impact the practice of clinical cytometry, as well as likely slow innovation in diagnostic medicine at least within the U.S. marketplace.  This document, entitled "Draft Guidance for Industry and FDA staff:  Commercially Distributed In Vitro Diagnostic Products Labeled for Research Use Only or Investigational Use Only" can be obtained from http://www.fda.gov/cber/guidelines.htm, searching for document number 1723.  Comments to this draft guidance are due to the FDA on August 29, 2011 by 4:00 PM EDT. with written comments to the Division of Dockets Management (HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm. 1061, Rockville, MD 20852. Submit electronic comments to http://www.regulations.gov.  This guideline is still a draft, so the cytometry community has time to make their voice heard about any potential impacts on either patient care or economic well being.

Early in the period of the FDA announcing their intent to become more actively involved in the regulation of LTD assay, a core group of organizers consisting of Brent Wood, Bruce Davis, David Barnett and Teri Oldaker decided to be proactive and organize a consensus meeting.  Bruce Davis had previously petitioned the ICSH board to establish a working group to create published ICSH guidelines for the validation of fluorescent cell-based diagnostic assays.  Recognizing the many unique features of validating assays where a cellular component or activity is being measured compared to measurements of soluble analytes, Brent Wood brought in the sponsorship of this activity by ICCS.  The goal of the initial meeting of this combined ICSH/ICCS taskforce was to develop a consensus document as guidance for any manufacturer, regulator or laboratory choosing to develop and proper validated a cell based fluorescent assay for diagnostic use. As guidelines developed by ICSH, similar to CLSI, are usually accepted by the FDA as guidance documents, the secondary goal of this working group is to created peer-reviewed ICSH guidelines for "Validation of fluorescence cell-based diagnostic assays", including antigen quantitation and intra-cellular antigen measurements that would be of immediate practical value.  If adopted as a guideline by FDA, then such a guideline would likely be the basis for FDA evaluation of FDA 510(k) and PMA IVD diagnostic submissions in this area.

The organizing committee invited 25 international experts based on interest and expertise in this area, to participate in a meeting to develop a guidance document on the validation of cell-based LDT assays. These experts represent assay developers, industry, academia, and government bodies (FDA, UKNEQAS, NIST, etc.) and a number of observers.  The intended audience included laboratories instituting LDTs, IVD manufacturers, regulators of IVD diagnostics, and laboratory professionals. The goal of the project is to develop scientifically evidence based guidelines for the validation of cell based fluorescent assays for diagnostic in vitro testing, which largely includes most diagnostic flow cytometry assays in current practice.  This project is currently endorsed by the ICSH and ICCS, but additionally underwritten and supported by the generosity of Abbott Diagnostics, Biogen-Idec, Mayo Laboratories, Beckman Coulter, Becton Dickinson, LabCorps, Arista Labs, Phenopath, Covance, Genoptix, Trillium Diagnostics, Nihon Kohden, and Horiba Medical. We are still accepting sponsorships for this important project (see levels of support below). Please contact Teri Oldaker or Bruce Davis if others would like to help sponsor this ongoing effort.

Platinum Level Support ($7,500 or more)	Send 2 observers to working group meetings.  Your observers would have the opportunity to review and have input into every draft prior to submission.
	Your institution acknowledged on the published document as a sponsor.
	Opportunity to purchase reprints at the preprint price from the publisher.
Gold Level Support ($3,500 )	Send 1 observer to the meeting.  Your observers would have the opportunity to review and have input into every draft prior to submission.
	Your institution acknowledged on the published document as a sponsor.
	Opportunity to purchase reprints at the preprint price from the publisher.
Silver Level Support ($1,000)	Your institution acknowledged on the published document as a sponsor.
	Opportunity to purchase reprints at the preprint price from the publisher.

The initial organizing meeting was held March 21-22, 2011 at the Lucerne hotel in Holden, Maine. Bruce Davis introduced the meeting along with history and meeting goals. Some meeting participants presented relevant topics and areas of work in this area for the first part of the morning. The group divided into four subgroups that focused on Pre-analytical Variables (lead Dr. Steve Kussick), Analytical Validation (lead Dr Vince Shankey), Post-analytical Issues (lead Dr. David Barnett) and definition of Performance Specifications (co-leads Drs Virginia Litwin and Dragan Jevremovic).  Each group spent the afternoon reviewing current publications, brainstormed and created an outline of relevant areas to include in the guidance document. The next day we reconvened as a large group and reviewed the preliminary work. We have set a goal of the end of June 2011 to have draft documents for review. We intend to complete the review process by October 2011 and to publish a guidance document in the ICSH and ICCS journals (International Journal of Laboratory Hematology and Clinical Cytometry) later this year.  
      
We will be presenting more details about this project at this year's ICSH meeting in New Orleans, LA during last May and the upcoming ICCS meeting in Portland.

Teri Oldaker, MLS (ASCP), QCYM
Genoptix Medical Laboratory, Carlsbad, California.

Bruce Davis, MD
Trillium Diagnostics, Bangor, Maine