Global Consortium for the Standardization of Biomarkers
Reference Materials Teleconference MINUTES
Attendance: Henrik Zetterberg & Holly Soares, Maria Carrillo, Bob Dean, Randy Slemmonn,
Mary Savage, David Stewart, Anne Fagan, Bud Kukull, Andy Lockhart
I. Introduction of Co-Chairs and Membership – Maria Carrillo
a. Henrik, Holly and Piotr will be co-chairs for this group.
II. Review of key issues for Reference Materials Objectives:
a. Can we come up with a universal calibration effort? Is this what Reference
materials mean? Holly introduces this question and wants to know if it is
broader than this.
b. Henrik has perspective that we could go for materials that we can use to
calibrate. They will have to define role of internal control samples. The
global material for calibration of assays should be the main goal of this group.
Calibration material is internal ref standard for curves of calibration. Bob
Dean conveys his thoughts; it has been the practice for a lot of
endocrinological assays to look at a macromolecule protein to prepare some
material in the natural matrix. In this case CSF, where there is a value
assignment, typically a specimen pool and there is a value assigned to it and
aliquoted and made available to researchers and companies so that taking
that biological matrix with the protein of interest can be used and results
generated with that ref material, the same number can be generated by each
group and used for measurement. This is not for defining individual
calibration curves for consistent results for that material.
c. Holly asks how we want to approach this, is a universal standard of truth for
all assays possible? Bob mentions that if you create a chemical substance and
put it into a matrix material buffer typically used for assays and all set up
calibration curves and take assays applied to biological samples collected
from patients you have to assume that the buffer matrix ahs the same
response as the natural material which is where we usually fall apart.
III. Could this be an equivalent matrix, or does this have to be a standard?
a. Henrik comments that he thinks we could do some ref material use different
formulations like CSF pool with hi abeta spiked into it or some other,
artificial CSF with serum spiked for abeta and see how it behaves with regard
to dilution and spike recovery etc. We need to do some pilot experiments on
this, Mary agrees that we need human CSF and QC ref standard with or w/o
CSF but need some experiments and compare them and come up with pools
that can be shared. We can use small volumes for experiments. A suggestion
for different forms of possible reference materials is needed, because we may
have this easily done through Henrik. Holly mentions that long term
solutions are also needed because companies need a solution. Endogenous
forms can be used but they aggregate and they are hard to standardize so
perhaps we should start with synthetic/derived peptides engineered with
abeta which takes out part of the molecule but we need to establish that it is
similar to endogenous.
IV. An important question is which peptide we will use to start, are we going to do
Ab42, tau, p-tau?
a. Bob cautions: If we start with synthetic product with ab42 altered mid
domain portion of the molecule you can change tertiary structure of molecule
and as a results you might actually alter immunoreactivity in ELISAs, Bob has
experience with this with intent to change immunoreactivity and has
diminished the binding of the antibodies and raises concern that this would
then might be a problem.
b. Need to be very clear about modifications. So it is clear we are not calibrating
to native ab42. So the first step to establish equivalence of the two, and
across multiple assays. Require what assays we would be attempting to
calibrate.
c. We should start with making synthetic reference material with ab42 as pilot
and then branch to t-tau. Biggest challenge with ab42.
d. Need to get Roche, Innogenetics, OCD, Mesoscale, Holly will try to get Roche
and OCD and Maria will reach out to Innx and Punkaj will be on calls. David
from Meso on call and he said he thought this was a rational approach. David
is on the call on behalf of Punkaj Oberoi. So bringing back this reference
material with the methods group in January would be helpful.
e. Bob asks if this group were to establish an engineered peptide material for
basis for calibration would we turn to the methods group and ask them to
use that to establish a mass spec (MS) method for calibration. So used MRM
to measure both native and synthetic, what would we define as truth if they
were different holly mentions. They will need to know what we focus.
f. Henrik says what we would like to create a material using CSF with identified
high ab42 concentration and have to do something about matrix effect and
see if we can dilute so can cover relevant ranges of ab42 for clinical ranges
and give to methods group assign the concentration in their method using
research use only assay .
g. Bob asks Henrik about his lab assays, Henrik lists what he has experience
with and access to so that Henrik lab can run this possibly in a pilot fairly
quickly with Innx ELISA, Mesoscale, Innx Luminex Innobia , Alphalisa.
Calibration standard for all Innx is probably same. Alpha may be different;
ab42 peptide is used for that one. David uses normal native peptide. We will
need to survey the manufactures to find out how they prepare their native
materials, many are using commercially available ones and do some
adjustment to them but they can provide the information to Henrik would be
helpful. Henrik will make an attempt to get that info. If we are moving
towards a global standardization, if they don’t engage with us they run the
risk of being on the outside looking in. So they would/should be willing to
engage.
h. Mary asks about any assays some companies are pursuing, would be able to
get them to the table? That is possible. We want to know, Roche and OCD.
And Millipore also, as well as Covance. Manufacture would have to test their
assay with our agreed upon material. We do not have to consider all the
companies now, but at least we should get a sense of those with commercial
assays and create a material to satisfy those providers which majority are
using. Then the material and reference method provide the opportunity for
new players to connect what has already been done.
i.
Fujirebio-Innx, Roche, MSD, OCD? GE is possible (Holly will reach out).
j.
Henrik mentions patients in his group with normal pressure hydrocephalus
and they are tapped so they do some cognitive tests and motor and then have
CSF removed to see if there is an improvement with removal. This CSF is
highly enriched and could be used.
k. Bop mentions that it might help us to have a shared website, so that we can
share documents and references that we are citing. The Association will add
a micro site to the GSBC website for this. Maria will take care of this.
V. ACTION PLAN/NEXT STEPS:
a. Ab42 starting point for synthetic ref material plan.
b. Roche OCD, GE will be contacted by Holly, 30 min of time at our next meeting
or sep meeting may be required. Innx and MSD already on the calls, Hugo is
representing ADXNeurociences. (Holly)
c. Henrik will poll assay companies for information about their current peptide
standards and put that information on our site and be circulated. (Henrik)
d. Website needs to be formed. (Maria)
e. Pilot experiment within the next few weeks (Henrik) to explore some
different candidates of reference materials, Henrik will try to create protocol
and share it with group and send in minutes. Focus on the linearity piece and
the most important to get a high concentration for dilution would be the goal.
f. Slide deck that outlines what our objectives are and who the team is. Maria
will create and route for objectives. (Maria)
VI. Next calls:
Monday 11/28 - 6:30 am PST / 8:30 am CST / 9:30 am EST / 3:30 pm Sweden
Monday 12/12 - 6:30 am PST / 8:30 am CST / 9:30 am EST / 3:30 pm Sweden
Monday 12/19 - 6:30 am PST / 8:30 am CST / 9:30 am EST / 3:30 pm Sweden