RE: [Histonet] AFB= bad ctrl for Fite, Negative controls, decloak er,egfr

From:"Poteete, Jacquie A."

Running the EGFRs in duplicate seems to be a bit of overkill.  The kit
received FDA approval based on the testing of the clone and the components
of the kit.  As the Erbitux rep explained to us, the drug is dispensed based
upon results from the DAKO EGFR-Dx only.  Of course, I suppose this premise
is good in theory, but we all know that some Oncologists don't always follow
each and every rule.  Just my humble opinion.

Jacquie Poteete, MT(ASCP)QIHC
Lead Technologist, IHC Laboratory
Saint Francis Hospital, Tulsa, OK

> -----Original Message-----
> From:	Richard Cartun []
> Sent:	Friday, May 07, 2004 2:06 PM
> To:;
> Subject:	Re: [Histonet] AFB= bad ctrl for Fite, Negative controls,
> decloaker,egfr
> Dear John:
> I was interested in your comments regarding EGFR testing.  I have been
> using Zymed's mAb (clone 31G7) for years and it almost always gives more
> immunoreactivity than the mAb in DakoCytomation's EGFR kit.  For the
> determination of patient eligibility for anti-EGFR therapy, we report
> the result for the Dako test, but we always run the Zymed mAb in
> parallel, and sometimes use it to help us determine if a patient's tumor
> is truly positive (or negative).
> Richard Cartun
> >>> "JOHN COLEMAN"  05/07/04 02:48PM >>>
> Using an AFB control for a Fite stain is a dangerous game! It is quite
> possible for the control to look positive when the capsule of the
> bacteria in question on the test slide is present and dissolved and the
> slide therefore looks negative!
> For Negative controls, in addition to matching all the rest of the
> protocol like you already are doing, you must at least also apply the
> same diluent used for the primary antibodies since letting the slide dry
> out will in most cases alter the stainability of the slide if there were
> an issue of false positivity gotten from the secondary reagents,
> retrieval or other ancillary procedures or reagents.
> Biocare's decloaker is basically a fine tuned lab grade pressure
> cooker- we use neither. We tried the pressure cooker offered by
> Cellmarque, and it saved us no time, and did not significantly improve
> retrieval.What antibody are you having trouble with? I could tell you
> what we do if it's one we use. 
> I tested 6  EGFRs on 45 breast cancer and 30 colon cancers looking for
> a percentage that matched that of Dako's kit and I have to say that the
> kit's clone is the best I've found. The other clones have a 5-10 %
> staining of all cases and The Dako kit had a yield closer to 50%, which
> is what the research for the drug claims. We bit the bullet ( price tag)
> and now order the kit.
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