FYI
Linda A. Sebree
University of Wisconsin Hospital & Clinics
IHC/ISH Clinical & Research Laboratory
DM223-VA
600 Highland Ave.
Madison, WI 53792
(608)265-6596
FAX: (608)262-7174
-----Original Message-----
From: Mary Cheles [mailto:mynerva7 <@t> msn.com]
Sent: Friday, March 05, 2004 8:54 AM
To: 'Van Eyck Deb'; Rena Fail
Cc: Ihcrg
Subject: Re: [IHCRG] Very important question!!!!!!!!!!!!!!!!
Hello All,
I will preface my remarks by stating that I am employed by DakoCytomation as the US Manager for pharmacoDiagnostics which includes the EGFR pharmDx kit. I am more than happy to answer any questions that you may have either by email or phone. I would like to take this opportunity to respond to some of the questions that have already been posed. The EGFR pharmDx kit received FDA approval in conjunction with Erbitux on Feb 12, 2004. Erbitux is a new monoclonal antibody therapy that binds to the extracellular domain of EGFR and is used for metastatic colorectal cancer patients who are refractory to irinotecan therapy.
The EGFR pharmDx kit's FDA approval is to aid in identifying colorectal cancer patients eligible for Erbitux therapy. The EGFR pharmDx assay was used to determine eligibility of all patients entered into all the Erbitux clinical trials (entrance into the trial required positive EGFR expression). The clone in the EGFR pharmDx kit (2-18C9) is a monoclonal and due to its use in the clinical trials is directly linked to patient outcome. Therefore, matching an alternative antibody to its sensitivity and specificity with total precision would not easily be accomplished.
The staining pattern for EGFR is primarily membranous (complete and incomplete) although some staining may be observed in the cytoplasm and extracellular spaces. Also contributing to a 'different' look than we are accustomed to with HER2 staining is that they are many normal cells that will mark with EGFR (epithelial & non-epithelial). Colorectal tumors tend to stain heterogeneously - this is part of the biology and again presents a different look than what we are used to seeing.
Bristol Myers Squibb (a large pharmaceutical company & the US distributor of Erbitux) is working closely with your oncologists. Their FDA approved package insert does specify that EGFR testing with the DakoCytomation EGFR pharmDx assay is required to determine patient eligibility for this therapy. Therefore, most labs are receiving very specific requests for this test. Certainly for this specific purpose, the kit should be used to comply with the FDA approval. The EGFR pharmDx kit can obviously used to stain for EGFR for other reasons as well although labs may opt to use a different EGFR antibody for that use. It would entail having two EGFR antibodies/protocols on-line in the lab and clearly differentiating when to use which.
Regarding fixation and processing... The Package Insert only states that "Biopsy specimens must be handled to preserve the tissue for IHC staining. Standard methods of tissue processing should be used for all specimens." There is a list of 6 fixatives which have been validated for use. I would be happy to email an electronic copy of the Package Insert to anyone interested in reviewing it.
Specifically to Deb, the heavy cytomplasmic staining that you have seen is uncharacteristic. I know that our Technical Service Group is working with you to identify what is causing this in your lab.
Please feel free to contact me for additional information.
Mary Cheles, MPH, HTL, DLM (ASCP)
805-566-5492
mary.cheles <@t> dakocytomation.com<mailto:mary.cheles <@t> dakocytomation.com>
----- Original Message -----
From: Rena Fail<mailto:rfail <@t> charleston.net>
To: 'Van Eyck Deb'<mailto:deb.vaneyck <@t> phci.org>
Cc: Ihcrg<mailto:ihcrg <@t> yahoogroups.com>
Sent: Friday, March 05, 2004 3:15 AM
Subject: RE: [IHCRG] Very important question!!!!!!!!!!!!!!!!
We are also using Zymeds EGFR with very good results. The kit from DAKO
is expensive, but we do expect to have request for this test from the
oncologist. We have not yet tested the kit.
Rena Fail HT(QIHC)ASCP
-----Original Message-----
From: Van Eyck Deb [mailto:deb.vaneyck <@t> phci.org]
Sent: Thursday, March 04, 2004 11:27 AM
To: 'ihcrg'
Cc: Kueck Brian D; Bayliss Katherine; Ferguson David J
Subject: [IHCRG] Very important question!!!!!!!!!!!!!!!!
Hi and I would like feedback from clinical folks out there--------have
you started running your EGFR kits on patients yet???? How is the
staining???? I ran a number of random cases and seem to be getting
darker staining and more cytoplasmic reaction than suggested. My negs
are great and clean-kit exactly followed. My cervix is much darker than
in picture in old guide and the diffuse cytoplasmic staining
predominated most cases making the membrane staining hard to evaluate.
What is your experience?? Most of my cases are 6 months or less tissue
cases.
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