Skip to Main Content

Precision Medicine vs Persuasion Medicine: Measuring vs Reading HER2

February 22, 2023

Yale Cancer Center Grand Rounds | February 21, 2023

Presented by: Dr. David Rimm

ID
9544

Transcript

  • 00:00I'm, I'm iron crop.
  • 00:02I'm the CTO director here and it's
  • 00:06my pleasure to introduce David Rimm,
  • 00:08who has many of you know is the Anthony Brady
  • 00:11Professor of Pathology and medicine here.
  • 00:14He is a Hopkins alum, did an MD PhD there,
  • 00:18then came here for for pathology residency
  • 00:21and then did a psychopath fellowship
  • 00:24at the Medical College of Virginia.
  • 00:27He's actually now been at
  • 00:29Yale for almost 30 years.
  • 00:31That's impressive.
  • 00:32He's the director of the Pathology
  • 00:35tissue service here and serves as
  • 00:38director of Translational Pathology.
  • 00:40You know, I think David has been
  • 00:42at the forefront of.
  • 00:44I guess I don't need to as in the
  • 00:47forefront of quantitative pathology
  • 00:49for for many years and he's well
  • 00:53known throughout the the, the.
  • 00:55The field for this he developed
  • 00:57many novel assay techniques for
  • 01:00identifying predictive markers to
  • 01:02determine which tumors are sensitive
  • 01:05to which targeted therapies.
  • 01:07And this has become increasingly
  • 01:09important as the number of targeted
  • 01:11therapies has increased and our
  • 01:12use of those drugs has increased.
  • 01:14And today he's going to focus on the
  • 01:16development of companion diagnostics
  • 01:18for her two directed therapies.
  • 01:20I think this is particularly timely as
  • 01:23the first her two targeted therapy for non.
  • 01:26Fish amplified breast cancers was
  • 01:28just approved six months ago and how
  • 01:31exactly we identify which patients
  • 01:32are going to benefit from this therapy
  • 01:35I think is a huge question and the
  • 01:37one the field is struggling with and
  • 01:39David's made a lot of inroads into that
  • 01:41and I think he's going to focus on,
  • 01:42on on that today.
  • 01:44So thank you for bringing this
  • 01:46timely discussion to us.
  • 01:51OK, great. Thanks, Diane, and thanks to
  • 01:54the leadership for inviting me today.
  • 01:56But thanks especially for
  • 01:57Ian for introducing me.
  • 01:58He's a world leader in this space
  • 01:59that I'm going to talk about.
  • 02:00That is the her two.
  • 02:0480C or antibody drug conjugate space.
  • 02:07I'll start by my title is precision
  • 02:09medicine versus persuasion medicine and
  • 02:11I'll get to what persuasion medicine
  • 02:13is a little bit more at the end.
  • 02:15And reading versus measuring.
  • 02:17And measuring is what you do quantitatively.
  • 02:20Reading is what pathologists do
  • 02:22when they look at slides and
  • 02:24difference between subjective and
  • 02:25objective assessment of tissue.
  • 02:30Let's see. Let's start with my disclosures.
  • 02:33As you can see, I do a fair bit of consulting
  • 02:36and a lot of the research in my lab,
  • 02:38including the work that led to this.
  • 02:40Most of what I'm going to present
  • 02:42today was sponsored by companies
  • 02:43including Sephylon and Kanika Minolta.
  • 02:47So today I want to spend the next 55
  • 02:50minutes or so talking about first and
  • 02:52quick introduction to the new drugs.
  • 02:54If you've heard Ian speak,
  • 02:55I don't need to give this part,
  • 02:56but maybe you didn't a proposed new assay
  • 02:59for these new drugs high sensitivity
  • 03:01would call the assay high sensitivity
  • 03:04or HS or two and then CAP CLIA,
  • 03:06what take, what does it take to get
  • 03:08something from your research lab so
  • 03:10that into a lab where we can deliver
  • 03:12information to patients and put the
  • 03:14results in the patient's chart.
  • 03:15That's what cap CLIA is taking the new.
  • 03:18Say to the clinic and then finally I'll
  • 03:20talk about precision medicine versus
  • 03:21persuasion medicine and try to talk all
  • 03:23of you who are oncologists in the room
  • 03:25and to not using persuasion medicine
  • 03:27and focusing on precision medicine.
  • 03:31So this is the, the big drug that got
  • 03:33the first standing ovation in 25 years
  • 03:35as I understand at ASCO and it it's,
  • 03:38it's the same old drug,
  • 03:39it's trastuzumab underneath,
  • 03:41but they've conjugated 8 topoisomerase
  • 03:44inhibitor payloads to the trastuzumab that
  • 03:47gives you especially some special tricks.
  • 03:50First of all, it brings these highly
  • 03:52toxic payloads right to the cell.
  • 03:53So it doesn't have the toxicity that
  • 03:56giving the drug and the dosages that
  • 03:58it would be given cause would cause.
  • 04:00All kinds of toxicity.
  • 04:02But if you bring it right to the
  • 04:03salad it causes less toxicity.
  • 04:05Whereas if you, and not only that,
  • 04:07when it gets uncoupled in the
  • 04:09cell it can spill out of the cell
  • 04:11and kill neighboring cells.
  • 04:13The so the the sort of neighborhood effect
  • 04:16or proximity effect of the therapy.
  • 04:20It worked really well and that's
  • 04:21why we've all heard about it that
  • 04:23you can see very few patients were
  • 04:26resistant but most patients had
  • 04:27some response and there were eleven
  • 04:29CR's in the early trials and in
  • 04:32fact it worked at for all patients,
  • 04:35but especially in patients that
  • 04:36were not amplified for her too.
  • 04:38So the initial trials were all in
  • 04:40patients that had her two amplification,
  • 04:42but then they started trials on
  • 04:44patients with low her two IHC 2
  • 04:46plus and HC1 plus and you can see
  • 04:48the curves look pretty similar.
  • 04:50And in fact in those low,
  • 04:51low patients in the Destiny 4 trial,
  • 04:54ultimately the survival curve
  • 04:55looks like great, looks like this,
  • 04:57which is really a great improvement
  • 04:59in the survival curve for advanced
  • 05:01breast cancer and changing median
  • 05:02survival from 5 to 9 months.
  • 05:04And that's I think what ultimately
  • 05:07has led to the popularization of this
  • 05:09drug and the success of the drug.
  • 05:11And they said we concluded a
  • 05:13randomized 2 group open label phase
  • 05:15two trial with her too low.
  • 05:17What does that mean?
  • 05:18So that's what we'll examine the rest, but.
  • 05:20Before we go there,
  • 05:21what about her 20?
  • 05:22What about if they don't express
  • 05:24any her two at all and can we tell
  • 05:26the difference between her 20 and
  • 05:27her two low and in fact in her two
  • 05:30zeros and this there is a trial
  • 05:31going underway that's her two less
  • 05:33than one but greater than zero.
  • 05:35That's the Destiny 6 trial
  • 05:37hasn't reported yet.
  • 05:38But there's also the her 20 equal 0
  • 05:40Daisy trial which was a small trial
  • 05:42in France where there was clearly
  • 05:44in these waterfall plots clearly
  • 05:46patients that benefited from drug
  • 05:48even though they had a hurt 2 = 0.
  • 05:51So is this the why is it important
  • 05:53to understand this and have good
  • 05:55diagnostics for it because this
  • 05:56drug is the tip of the iceberg.
  • 05:58Here's a list of other drugs
  • 05:59which there's no way you can read,
  • 06:01but all of these drugs are,
  • 06:02are all these are targets for
  • 06:04ADC's in clinical trials.
  • 06:06So I think ADC's may become very
  • 06:08important for oncology in the next
  • 06:10few years and equally important
  • 06:12will be companion diagnostics that
  • 06:13actually pick the right patients as
  • 06:15opposed to giving the drug because
  • 06:17unlike when we know the tiger it so
  • 06:19well and we know how the drug works.
  • 06:21It's really important to be able to
  • 06:22pick the right target or to pick
  • 06:24the right patients that express
  • 06:25the right amount of target.
  • 06:26So what do we do now?
  • 06:27So this is the standard practice guidelines,
  • 06:29ASCO CAP guidelines in 2018 and
  • 06:32these guidelines are how we practice
  • 06:35as pathologists in assessment
  • 06:37of her two expression.
  • 06:38And this is the algorithm for what
  • 06:41we look at when we look at the slide
  • 06:43circumferential staining that is complete,
  • 06:45intense and greater than 10% of the cells.
  • 06:48That makes the three plus
  • 06:49and then we have a 2 + 1 +.
  • 06:50I won't go through them all,
  • 06:52but they're kind of summarized
  • 06:53here where one no staining,
  • 06:55no membrane staining observed is a 0 +
  • 06:571 is faint partial membrane staining
  • 07:00and weak to moderate staining is +2.
  • 07:02That's kind of subjective. In fact.
  • 07:05How well can we do that and
  • 07:07how important is it?
  • 07:07Well.
  • 07:08It used to be important to tell
  • 07:10the heart threes the the three
  • 07:12pluses from the others and the
  • 07:14two pluses were they the reflex.
  • 07:16But now it's important to have this CAD.
  • 07:18The new category is far too low.
  • 07:20And how many are there?
  • 07:21There's a lot,
  • 07:22maybe as many as 65 or 70% of the
  • 07:25patients are thought to fall into this low,
  • 07:27her two low category which means
  • 07:28a lot of patients could get drug,
  • 07:30but it also means that we need to be
  • 07:32as accurate as we can and assigning
  • 07:34those patients because we don't want
  • 07:36the her two zeros to get the drug
  • 07:38if they aren't going to benefit.
  • 07:39Well, maybe we do.
  • 07:40We'll talk about that later.
  • 07:41But so how do we know how,
  • 07:43how well do we do at this?
  • 07:44Her too.
  • 07:45So I'm fortunate to be on the
  • 07:47immunohistochemistry committee of
  • 07:48the College of American Pathologists.
  • 07:50And so I get access to the
  • 07:52surveys that make Clea labs,
  • 07:54what CLIA labs are.
  • 07:55That is,
  • 07:55for a CLIA lab or clinical lab
  • 07:57to return data to the chart,
  • 07:58they have to do a survey twice a
  • 08:00year to show that they're competent
  • 08:02and effective at doing the assay.
  • 08:04And here's the surveys for anatomic
  • 08:06pathology for her two using a tissue
  • 08:09microarray. This is her to a 2020.
  • 08:11So it was the fall survey or the
  • 08:13spring survey from 2020 from the
  • 08:15College of American Pilot Pathologists.
  • 08:17And you can see my colleagues here,
  • 08:18including myself, who are on this committee.
  • 08:20And when we looked at these surveys,
  • 08:22we noticed that four, six and seven,
  • 08:24that is 3 out of 10 did not reach consensus.
  • 08:27That means that of the 1400 labs
  • 08:29in the in the world that did this,
  • 08:32they couldn't come to an agreement.
  • 08:34That is,
  • 08:34you need to have 90%
  • 08:36consensus to have agreement.
  • 08:37In fact, if we look at this one,
  • 08:39it's interesting.
  • 08:39This is one of the cases that didn't
  • 08:42come to agreement and that was
  • 08:44because there was a big discordance
  • 08:45in the number of called 0 versus
  • 08:471 and there were a fair number
  • 08:49that even called it two or three.
  • 08:50So that's troublesome.
  • 08:51If we're testing these labs twice a year
  • 08:54and we're assuring that they're giving
  • 08:56the right answer for the patients,
  • 08:58how can you have that much difference
  • 09:00between zero and one that it's almost 5050.
  • 09:03So since I I'm on the CAP committee,
  • 09:05I could ask for the data from
  • 09:07the last few years.
  • 09:08And here's the data from
  • 09:09the lab from 2019 and 2020.
  • 09:12And of the 80 cases,
  • 09:14fifteen of those cases showed a
  • 09:16discordance of greater than 25%.
  • 09:17And that's shown in these pie
  • 09:19charts here where the zeros are
  • 09:21blue and the ones are red and
  • 09:23anything higher than one is black.
  • 09:25Two and three,
  • 09:26since we're not going to focus on that.
  • 09:27So we we did,
  • 09:28we thought is this really, you know,
  • 09:30this is concerning,
  • 09:31but you know what this is tissue microarrays.
  • 09:33This is not what happens in the real world.
  • 09:35So then we did a study of real
  • 09:37world core biopsies.
  • 09:38And enrolled 18 pathologists from 15
  • 09:40institutions around the United States
  • 09:42and ask them to read actual core
  • 09:44biopsies that have been read at Yale.
  • 09:46We collected 170 cases from Yale
  • 09:48and had them score them according to
  • 09:51the ASCO CAP guidelines before the
  • 09:54publication and the popularization
  • 09:55of her two one plus versus 0.
  • 09:58So they didn't know they were just
  • 10:00doing the ASCO CAP guidelines as
  • 10:01they always have, and scoring 0123.
  • 10:04And what they did,
  • 10:05what they're scoring looked like was this.
  • 10:07That is, the Blues were the zeros.
  • 10:08This is the percent of pathologists.
  • 10:10That scored at 0,
  • 10:12so a fair number agreed that
  • 10:14that there were zeros.
  • 10:15There were 92 cases that were discordant,
  • 10:18and of those,
  • 10:209269 were discordant between zero and one,
  • 10:23and only twenty were discordant
  • 10:25between 2:00 and 3:00.
  • 10:26So this actually was.
  • 10:28Through many reviewers,
  • 10:30ultimately got us published in JAMA Oncology.
  • 10:34How come it's not advancing now?
  • 10:38Oh, hold on. I lost my laser pointer.
  • 10:44Microsoft doesn't want me to do this now.
  • 10:45It's the screen has turned
  • 10:47Gray as it's saying restart.
  • 10:49I probably shouldn't.
  • 10:50I should probably wait for
  • 10:51the program to respond.
  • 10:53Very sorry about this,
  • 10:54but suffice it to say that I'll skip
  • 10:57the next slide so we can keep going.
  • 10:59The next slide was after
  • 11:00many review rounds of review,
  • 11:02we did get this published in JAMA Oncology,
  • 11:04but weren't allowed to say
  • 11:05what we wanted to say,
  • 11:06which is that there's really a
  • 11:08great discordance between zero and
  • 11:09one and not so much discordance
  • 11:11between 2:00 and 3:00.
  • 11:12And I don't know if we have
  • 11:13should I restart the program?
  • 11:14I don't know if we have any IT
  • 11:16people here that or how long we're,
  • 11:17you know,
  • 11:18we'll be here for the next 45 minutes
  • 11:20waiting for the computer to come along.
  • 11:25Wait to respond or restart the program.
  • 11:28Maybe I should restart the program and
  • 11:29that will take several minutes too.
  • 11:31It's just it's just not rebooting
  • 11:33the computer, it's just. Yeah.
  • 11:37Let's try again. Yeah, we're good.
  • 11:41We're good. Sorry about that. OK.
  • 11:43We saw all those things already.
  • 11:45Let's go to. The study that was in
  • 11:49JAMA Oncology was here and this is
  • 11:52what was the this is the figure and
  • 11:54and Eileen Fernandez was the lead
  • 11:56on this study in my lab and she.
  • 11:59Did the analysis that is shown here
  • 12:00that shows that there's a lot more
  • 12:02discordance between zero and one
  • 12:04than there is between 2:00 and 3:00.
  • 12:06And for two we have a solution.
  • 12:08For two we can do fish,
  • 12:09so we have a orthogonal assay.
  • 12:11What do we do between zero and one?
  • 12:12Well, we don't have a solution yet.
  • 12:14That's what I'll show you in a minute.
  • 12:16But also you can look at this analysis
  • 12:19which which shows you this is a work
  • 12:21done by Jack Robbins in the lab with
  • 12:24Eileen Fernandez showing the percentage
  • 12:26of people that called 0 versus called one.
  • 12:29And so if your pathologist #18 and
  • 12:31these are all currently signing out
  • 12:33pathologists most with more than five
  • 12:35years of experience around the country.
  • 12:37So these are not residents or not to say
  • 12:39that residents can't do this just as well.
  • 12:42But these are not residents
  • 12:43or or or laboratorians.
  • 12:45These are sign up with ologists.
  • 12:47And if you're pathologist 18 you only
  • 12:49score 15% of the patients with a 0,
  • 12:52but if your pathologist number one,
  • 12:53you have 44%.
  • 12:54So whether or not you get trustors,
  • 12:57mab drugs,
  • 12:57tecan depends on who your pathologist is.
  • 12:59That doesn't sound like a great idea to me.
  • 13:02So what we asked is how many people
  • 13:04do you need to make sure that
  • 13:06an assay agrees with each other?
  • 13:08And we, we invented this with gang hand.
  • 13:10We invented this system to realize that
  • 13:13there's 21,000 pathologists just in the
  • 13:14US and at that and 100,000 in the world.
  • 13:17So how many do we need to decide
  • 13:19whether or not an essay is good?
  • 13:20And so we there, there is actually
  • 13:23no statistical method for this.
  • 13:24So we simply decided to plot
  • 13:26the overall percent agreement.
  • 13:28That's what overall LPA stands for
  • 13:30versus the observers or readers.
  • 13:32And what you see is that the more
  • 13:35observers you have,
  • 13:36the less agreement you have,
  • 13:37which makes sense.
  • 13:38The more people you ask,
  • 13:39the more discordance you're
  • 13:40going to get in your answers,
  • 13:41just mathematical truism.
  • 13:42And so does this actually work and
  • 13:45can this be used to assess assays?
  • 13:47So here's estrogen receptor.
  • 13:48Turns out we're really good
  • 13:50at estrogen receptor.
  • 13:51If you have a quartet of
  • 13:54pathologists read estrogen receptor,
  • 13:56all four of them will agree somewhere
  • 13:58between 85 and 95% of the time.
  • 14:01How do we do for her?
  • 14:02Too well, not so well.
  • 14:05This is the plot for her.
  • 14:062/3 plus or not three plus.
  • 14:08We're really good at that.
  • 14:09But if you have a quartet of pathologists
  • 14:124 decide whether it's zero or not zero,
  • 14:15it's between 40 and 80 percent,
  • 14:1885%. So this is a new method
  • 14:20to approach the analysis,
  • 14:21to try to figure out how many we
  • 14:23need and how many do we need to make
  • 14:24a new assay to make a good study.
  • 14:26Well, it's when it plateaus,
  • 14:27so in this case we probably need 9 or 10.
  • 14:30And this case, no number is sufficient
  • 14:31because it goes all the way down to the
  • 14:34baseline to tell ones from, not once.
  • 14:36So the point is, I think that.
  • 14:38I've I hope that I've convinced
  • 14:40you that we need a new assay.
  • 14:43And so that's what we have done,
  • 14:44is propose a new assay that's measured,
  • 14:47not red. And so based on that.
  • 14:50We start, we started from the beginning
  • 14:52with cell lines and these cell lines
  • 14:54are all cell lines that are amplified,
  • 14:56gene amplified and these cell
  • 14:58lines are all gene express.
  • 15:00Her too,
  • 15:01but are not gene amplified and
  • 15:03you can see when you plot them.
  • 15:05If you look with the current FDA
  • 15:07approved assay you can separate the
  • 15:09highs from the lows or the negatives,
  • 15:11but you can't stratify the negatives.
  • 15:14Whereas if you do the new assay
  • 15:15high cut 10 times more antibody,
  • 15:17pretty simple new assay.
  • 15:18You can then stratify the low cell
  • 15:20lines and tell the zeros from the ones.
  • 15:23Essentially if you were reading the
  • 15:25cell lines but it was the wrong,
  • 15:27the wrong the current assay is
  • 15:29the wrong tool for the job.
  • 15:31Or as was said by a group in France.
  • 15:36The current assay now FDA approved,
  • 15:38is like weighing mice on a
  • 15:40scale for elephants.
  • 15:41And I think this is really good
  • 15:43because everybody gets this if
  • 15:44you have a skill for elephants,
  • 15:45it doesn't work for weighing mice
  • 15:48and it's all about dynamic range.
  • 15:50So here's the assay we did we
  • 15:52invented and and this is to have
  • 15:54a a series of cell lines and then
  • 15:56just do like a Bradford assay like
  • 15:58we all did in college chemistry
  • 16:00for where we make a standard curve.
  • 16:02And we used our tissue microarray to
  • 16:04make cell lines and with the help of
  • 16:06array science made a standard curve.
  • 16:08And then with the help of Crotia we
  • 16:10figured out how many animals per
  • 16:12microgram there were in each of these
  • 16:14cell lines and then converted that
  • 16:16using Q path to how many animals
  • 16:18per square millimeter there are.
  • 16:19So now we have an assay.
  • 16:21That can tell us animals per
  • 16:22square millimeter.
  • 16:23And like all assays,
  • 16:24it saturates when it gets too high.
  • 16:26So the amplified cases are
  • 16:28saturated and we can't use those.
  • 16:30But since we don't really care
  • 16:31about 2 plus and three plus,
  • 16:32we got that pathologists can do just fine
  • 16:34in telling 3 plus from not three plus.
  • 16:36We need an assay to tell 0 from 1.
  • 16:39And so that's this assay works fine.
  • 16:40If we get rid of these two,
  • 16:42we can now build a very nice
  • 16:43standard curve that we can use
  • 16:45as a linear assay and then assign
  • 16:47each case and animals per square millimeter.
  • 16:49And so just to remind you.
  • 16:51I'm going to talk a little bit
  • 16:52about limits of detection,
  • 16:53limits of quantification,
  • 16:54and limits on linearity.
  • 16:55A little bit of essay terminology and we
  • 16:57and this is the range we want to be in,
  • 17:00not this range,
  • 17:00which is what the saturation range,
  • 17:02which is what the current
  • 17:04essay really focuses on.
  • 17:06Because really the current
  • 17:07assay all you need to tell is.
  • 17:09Is it saturated or not?
  • 17:11For the new assay we need
  • 17:12to tell how much they have.
  • 17:14So here's our the current our standard curve.
  • 17:17With the higher two assay and
  • 17:19you can see there's two positives
  • 17:20and the rest are negative.
  • 17:22So it works if you just want to
  • 17:24tell amplified from non amplified,
  • 17:26but what if you want to tell that
  • 17:27low range so you can see that you
  • 17:29can see the full dynamic range with
  • 17:31the new her two low assay antibody
  • 17:32concentration or that what we're
  • 17:34calling high sensitivity HSV or
  • 17:36two you can see in that range.
  • 17:38So now we have to talk about a
  • 17:39little bit of wonky stuff and
  • 17:41that is what are those things.
  • 17:42So what is the limit of detection,
  • 17:44what is the limit of quantification
  • 17:45or what is the limit of linearity.
  • 17:47So these are the definitions
  • 17:48and this is right.
  • 17:49One of the FDA's handbook on how they
  • 17:51advise industry to do this and you
  • 17:53can see that the limit of detection
  • 17:55is the lowest concentration of the
  • 17:57analyte that can be detected but
  • 17:59not but and reliably to strings
  • 18:01from zero but not necessarily
  • 18:03quantified that is too low.
  • 18:05So what we really want is to know
  • 18:07the limit of quantification because
  • 18:08then we can do it right every time.
  • 18:10But we don't yet know how much
  • 18:12her two is required to benefit
  • 18:14from trust who's mab drug stcan.
  • 18:16So we're going to measure all the
  • 18:18way down to beyond the limits of.
  • 18:20Our essay to to the LD and below and
  • 18:22see what we get and what we got is this.
  • 18:25When we did it on tissue microarray we
  • 18:27could see that the the zeros are blue,
  • 18:30the Reds are one, ones are red, the twos.
  • 18:32This is the pathologist read over here
  • 18:342 Plus is black and three plus is green,
  • 18:36and most of the Greens are
  • 18:37above our limit of linearity.
  • 18:39But look at how many twos and ones
  • 18:41there are in this middle range.
  • 18:43That would be called one.
  • 18:44And I think this is even further evidence
  • 18:46that we need a a quantitative assay.
  • 18:48We need a measured assay,
  • 18:49not a red.
  • 18:50Say,
  • 18:50in order to pick the right
  • 18:51patients for trastuzumab drugs,
  • 18:53tican and surprisingly there are some
  • 18:55patients most of whom were called 0,
  • 18:57but some were called one or two
  • 18:59that are actually below our limit
  • 19:01of quantification or even below our
  • 19:02limit of detection as I'll show later.
  • 19:04So then we did what you have to do in
  • 19:06a clear lab is did 40,
  • 19:08you have to do 20 positives and 20 negatives
  • 19:10according to Fitzgibbons at all in order
  • 19:12to bring your assay to the CLIA lab.
  • 19:14But we don't have positives and negatives.
  • 19:16We have a continuous scale.
  • 19:17So we did 40 of them and these
  • 19:19are actual core biopsies.
  • 19:20Now they're not tissue microarrays,
  • 19:22but you can see the same thing.
  • 19:23There's a fair bit of Miss Assignment
  • 19:25and in fact summarized here,
  • 19:27you can see that there's zeros and ones,
  • 19:30but there's a broad range of animals per
  • 19:32square millimeter for zeros and ones.
  • 19:34And the two plus not amplified almost
  • 19:37in fact does overlap with the two
  • 19:40plus amplifies and the three pluses,
  • 19:42which we're good at and we're pretty tight.
  • 19:45So how many are there?
  • 19:46Well, in our first forty there
  • 19:48was about 20% of the cases that
  • 19:50appear to be below the limit of
  • 19:52quantification for her two protein,
  • 19:54but potentially present and as
  • 19:57target for a target for TDXD.
  • 20:01So just to summarize to this point,
  • 20:03about 70% of the cases have low her two
  • 20:06defined as above the LQ and below the
  • 20:09levels associated with gene amplification.
  • 20:11About 8 to 10% are below
  • 20:13our LQ or even our LD.
  • 20:15It's probably about 6% below our LD.
  • 20:18Many of the cases that
  • 20:19are called her to zero,
  • 20:20as many as 60% are in our studies,
  • 20:21maybe 75% have detectable amounts
  • 20:23of her too between 3 and 20 animals
  • 20:26and the quantitative her two asset
  • 20:29could be envisioned as a reflex tax.
  • 20:31So that if you pathologist reads
  • 20:33an IHC equals zero,
  • 20:35they could then reflex to the
  • 20:36quantitative test and the same way we
  • 20:39reflex to fish today for A2 plus HC.
  • 20:43OK, so that's the proposed new assay.
  • 20:45Now let's take it to the clinic.
  • 20:47So what's involved in the next
  • 20:48step of taking to the clinic?
  • 20:50And I like to quote a colleague
  • 20:51of mine from Brigham and Women's
  • 20:53who said once you have the essay
  • 20:55working in your research lab,
  • 20:56you're 5% of the way there.
  • 20:58And I think that's really true.
  • 20:59Now having brought this assay
  • 21:01with hats off to Trish Gal who's
  • 21:03not here and has not left,
  • 21:05Nay Chan who was in the audience and Reva
  • 21:08come ova who have helped me to bring
  • 21:10this assay to the clinical setting.
  • 21:12So the things that you have
  • 21:14to do are antibody titration,
  • 21:15maximization of signal to
  • 21:17noise analytic validation.
  • 21:18I'll try to go through this stuff fast
  • 21:19because it's a little on the wonky side,
  • 21:21performance accuracy, precision,
  • 21:23sensitivity and specificity and
  • 21:25serial core reproducibility.
  • 21:26And then how do we tell our colleagues?
  • 21:28What do we tell the oncologists?
  • 21:29And then so the reporting is
  • 21:31part of this as well.
  • 21:32So first of all,
  • 21:33we looked at the signal to noise
  • 21:34and you can see that the peak
  • 21:36signal to noise is at 1 microgram
  • 21:37per mil for a new antibody.
  • 21:38This is a new higher
  • 21:40sensitivity antibody for her
  • 21:41too than the one that's
  • 21:43currently used in the clinic.
  • 21:45And we took and we picked the
  • 21:46concentration with the maximal signal
  • 21:47to noise and then we looked at the
  • 21:49accuracy and our accuracy isn't great,
  • 21:51it's only 87%. Why is that?
  • 21:54That's because we're more sensitive than
  • 21:56the status quo assay which we had to
  • 21:59compare it to which was HC012 and three.
  • 22:02But overall we have quite a quite
  • 22:05good concordance especially in the end
  • 22:07and more resolution in the low range.
  • 22:09And then our intra and intra
  • 22:11assay precision is quite high,
  • 22:1310% sounds like it might not be great.
  • 22:15To interact assay precision and actually
  • 22:17the essay that we just bridged to,
  • 22:19we're now under 10%,
  • 22:20but it's acceptable and the
  • 22:22intra assay precision,
  • 22:24this means to calculate the precision
  • 22:26three slides run on separate
  • 22:27trays at the same machine is,
  • 22:29is, is about 5%.
  • 22:30So these are where we want to be.
  • 22:33Our sensitivity compared to the historical
  • 22:35essay as 100% and our specificity is 84%.
  • 22:39Why is our specificity low?
  • 22:40Because we're more sensitive and
  • 22:42so we call cases positive that
  • 22:45we're called negative by IHC.
  • 22:47So here's the proposed clinical
  • 22:49future work workflow and this is
  • 22:51what we're doing now which is we
  • 22:53have we get the labs come to this
  • 22:55lab that I've called the qutab lab
  • 22:57quantitative diagnostics and anatomic
  • 22:58pathology which is a new lab which
  • 23:00is now open and open for business.
  • 23:02And we've now begun to do this.
  • 23:04This is and this is qdap essay #1,
  • 23:07the high sensitivity here.
  • 23:08Two,
  • 23:08we batched the stains and do them
  • 23:10in our like a bond stainer so that
  • 23:12they're done in an auto stainer
  • 23:13and then we read them originally
  • 23:15in some old like legacy hardware.
  • 23:17But now we're using this,
  • 23:18we just recently completed the bridge study,
  • 23:21although our license holder
  • 23:22hasn't signed off yet,
  • 23:23he will see it shortly and uses a
  • 23:26much more high throughput device.
  • 23:28Instead of an hour this machine would
  • 23:29take about four minutes to scan a slide.
  • 23:32So we wanted to update our technology
  • 23:34a little bit and then we signed
  • 23:35it out and Co path as a procedure.
  • 23:37And so it ultimately makes it to
  • 23:39epic and and clinicians can see it,
  • 23:41this is what it looks like.
  • 23:43The pathologist has to pick a region.
  • 23:44So we're actually not measuring
  • 23:46the entire core biopsy.
  • 23:47We're measuring a region that is
  • 23:49quote UN quote representative and
  • 23:51that representative region is
  • 23:52then looks like this.
  • 23:53This is actually not a brown stain
  • 23:55but a pseudo IHC which it shows the
  • 23:57pathologist what they what it looked
  • 23:59like and then the pathologist actually
  • 24:01sees the number of fields of view,
  • 24:03in this case 23 and the in this case
  • 24:06the rare sight score in this case was
  • 24:0915.4 animals per square millimeter.
  • 24:11So that will be included in the report.
  • 24:13We'd say 15.4 animals require millimeter.
  • 24:15We don't know what that means.
  • 24:17I mean,
  • 24:18we do know that it's detectable
  • 24:19and then
  • 24:20we can give a choice in our interpretation
  • 24:22that it's positive for expression high.
  • 24:24That is, it's above our limit of linearity
  • 24:26positive expression intermediate,
  • 24:28which means that it's like a one
  • 24:30or A2 positive for expression low,
  • 24:32which means it's.
  • 24:33Present, but it might not be reproducible.
  • 24:37That is, it's above our LOD but
  • 24:39not necessarily above our LOQ
  • 24:41and then negative below the LOD.
  • 24:43And so these are the reports that we'll
  • 24:45issue as as we start to receive specimens.
  • 24:48So far we've received a grand total of two.
  • 24:51We hope that after this talk and maybe
  • 24:54in the future and certainly in the more
  • 24:57distant future when we know how much.
  • 24:59Is necessary for patients to respond.
  • 25:02We hope that this essay will
  • 25:03gain some traction.
  • 25:04So our vision we currently offer HSR 2 in
  • 25:07the QDAP lab test must be requested by an
  • 25:10oncologist and the patients are billed.
  • 25:11If the test is requested by an oncologist,
  • 25:14there are I CD9 codes for all
  • 25:16the stuff we're doing.
  • 25:18We began a prospective study on all
  • 25:20breast biopsies so that we have data of
  • 25:23a year's worth of prospective data and
  • 25:26we're about seven months into it now.
  • 25:28We offer the essay coalitions
  • 25:30from to Yale or elsewhere who want
  • 25:33quantitative information,
  • 25:34but only two so far to date.
  • 25:36And then the discussions of the
  • 25:38license we will.
  • 25:38What we hope to happen is ultimately
  • 25:40it won't just be yell that can do this,
  • 25:42but we'll license it to some of
  • 25:43the big lab companies that provide
  • 25:45them the bulk of the service.
  • 25:47It's interesting to know and
  • 25:48interesting to me anyway,
  • 25:49that only 15% of lab tests in the
  • 25:52US are provided by academic labs.
  • 25:54The other 85% are provided by private labs.
  • 25:58And so clearly if we want to.
  • 25:59Have this effect patients around
  • 26:02the world and be useful and needs
  • 26:05to make it into private labs and
  • 26:07those discussions are beginning.
  • 26:09So the last thing I want to talk about is
  • 26:12the precision versus persuasion medicine.
  • 26:15And so our original envision for
  • 26:17this essay was that we would need
  • 26:20to adjudicate the IHC's equal 0.
  • 26:21And what we would do is we would get
  • 26:24all the HC equals zero and we would
  • 26:26measure them and then we tell you if
  • 26:28you're above the limit of detection
  • 26:30or above the limit of response.
  • 26:31We don't know the limit of response yet.
  • 26:33Someday we will and I'll show you
  • 26:35how we intend to get there.
  • 26:36But right now we don't know the
  • 26:38limit of response but.
  • 26:38You would take all the cases that
  • 26:40were called HC0 and maybe the cases
  • 26:42that were called HC One and do that.
  • 26:45But something happened in the last
  • 26:46three or four months and I haven't
  • 26:48been able to document it yet,
  • 26:50probably because it's not mature enough,
  • 26:52but suddenly the IHC equals zero is rare.
  • 26:55And that's because pathologists
  • 26:57are people too.
  • 26:58Pathologists sometimes might be
  • 27:00a little more lenient on what
  • 27:02they call IHC one and this code
  • 27:04called Sympathy vote because
  • 27:05then they can get this new drug.
  • 27:07Here are real quotes that I've heard.
  • 27:09I won't quote the people because to
  • 27:12not embarrass them or give them credit,
  • 27:14but here's a real quote.
  • 27:16Hi doctor pathologist.
  • 27:16So I see you called Missus
  • 27:18X's biopsy IHC zero.
  • 27:19That means I'm going to have
  • 27:21to offer her brain radiation.
  • 27:22Are you sure it's not H sequels one?
  • 27:24Then I could give her her and her two.
  • 27:28Should I go look at that slide again?
  • 27:30Does that mean that my first view
  • 27:32of that slide was not accurate?
  • 27:34Or was it accurate and maybe
  • 27:36I should change my diagnosis?
  • 27:39Because I'm persuaded that
  • 27:41that's better for the patient.
  • 27:43I'm not sure that's a great idea from
  • 27:45West Coast director of pathology service.
  • 27:47Yeah, we don't have many
  • 27:48IHC's equal 0 anymore.
  • 27:50And from a Midwestern oncologist,
  • 27:52I'm not seeing the response rates
  • 27:53and in her two patients that
  • 27:55they saw in the clinical trial.
  • 27:56They're getting a lot of IHC zeros and
  • 27:59maybe IHC zeros really don't respond.
  • 28:01We know that eight to 10% of the
  • 28:04cases really don't express any target
  • 28:06and this is a targeted therapy.
  • 28:08I mean we don't definitively
  • 28:09know how the drug works,
  • 28:10but we think it's a targeted therapy.
  • 28:13After all,
  • 28:14it's trastuzumab conjugated to toxins.
  • 28:16So what's happened is that really
  • 28:18now we need to adjudicate the one
  • 28:21pluses what we really need because
  • 28:23the zeros have minimized, not,
  • 28:25I don't want to say they've gone away.
  • 28:27If you ask pathologists,
  • 28:28they will sternly tell you yes,
  • 28:30of course we still call IHC 0.
  • 28:32But.
  • 28:34Data will set will will tell us
  • 28:36in a year or so from now how
  • 28:38our IC0 calls changed.
  • 28:40But but I see one is now more common
  • 28:42and so if it's if it's more common
  • 28:44maybe that's the one we should be
  • 28:46measuring and in fact that's the plan.
  • 28:48So there are a few different ways
  • 28:51we're going to study IHC equals one.
  • 28:53The first is the Qdap Labs
  • 28:56prospective study and this is
  • 28:58copied with me by name by Nate Chan,
  • 29:01who's the director of the Q dot lab.
  • 29:03And you can see we began August
  • 29:051 and we'll go till July 2023
  • 29:07and today we have 226.
  • 29:09I anticipate we'll get around 400.
  • 29:12The inclusion criteria will be any
  • 29:13case and the primary objective will
  • 29:15be to determine the number of H0 cases
  • 29:18that have detectable her two expression.
  • 29:20So how many IHC zeros?
  • 29:21And this study was designed
  • 29:23before everything.
  • 29:23Name HC One,
  • 29:24but how many HC Zeros have above
  • 29:26the limit of detection and how many
  • 29:28HC ones have below the limit of
  • 29:31detection will be interesting as well.
  • 29:33That's a secondary,
  • 29:34that's a secondary objective of the
  • 29:36study and the study is in process
  • 29:38and we all just to show you a peak,
  • 29:41we've already started doing some
  • 29:42quantitative work and in fact
  • 29:44you can see from quantitative,
  • 29:45this is quantification of prospective
  • 29:48tissue from the clinical trial
  • 29:50and you can see the lol in this
  • 29:53case was 33 and the OD is 3.
  • 29:55This is all done on the new platform
  • 29:57and you can see that there's a lot
  • 29:59of cases that are called zeros that
  • 30:01are above our limit of detection.
  • 30:02There's not as many.
  • 30:03So far it looks like we're going
  • 30:05to not have very many that are
  • 30:06below our limit of detection,
  • 30:08but time will tell as we get
  • 30:10as the study
  • 30:10matures. There's two other studies
  • 30:13that were progressing on one is a
  • 30:16TB CRC study report proposal with
  • 30:18Ian and Eric's arrival at Yale,
  • 30:20we became part of the Translational
  • 30:23Breast Cancer Research Consortium,
  • 30:24which is a group of 16 or 17.
  • 30:26Now institutions that do studies
  • 30:29together on translational research
  • 30:30and the goal of this study that
  • 30:33is still in proposal stage is to
  • 30:35evaluate her two measurement in
  • 30:36the one plus metastatic cases.
  • 30:38So if we get one pluses and we get 2 or
  • 30:41300 from 17 institutions around the country,
  • 30:44we should be able to tell how
  • 30:46frequently we see the patients
  • 30:48that have one plus actually don't
  • 30:50have any target and vice versa,
  • 30:52we should be able to see response
  • 30:54since all those patients since they
  • 30:55were called one plus will be get.
  • 30:57Drug will be getting trustors map drugs
  • 30:58he can and be present in the residency.
  • 31:00So here's the study a draft of the
  • 31:03study objectives to evaluate the
  • 31:04real world relationship between
  • 31:06quantitative her two expression QIF
  • 31:08and objective response in patients
  • 31:10with her two IHC plus one and
  • 31:13metastatic breast cancer receiving TXT.
  • 31:15And then there's a number of secondary
  • 31:17objectives that are shown here as well.
  • 31:19And then a second study that I,
  • 31:21I don't even have a slide for yet
  • 31:24is that we proposed a study led by
  • 31:26Merriam Lustberg here of patients
  • 31:29who get HC0 and then prospectively
  • 31:31giving them TXD much the way the
  • 31:35Daisy trial worked on that study
  • 31:38is not yet completely designed
  • 31:40and not yet completely approved.
  • 31:42So I don't have any slides to discuss it,
  • 31:44but I think those are the kinds of studies
  • 31:46we need where we have patient response.
  • 31:48Either real-world patient response or
  • 31:50clinical trial patient response in order
  • 31:52to figure out the animals per square
  • 31:54millimeter above which patients benefit.
  • 31:56Will it be a cut point?
  • 31:57Probably not.
  • 31:58Probably there will be patients with
  • 32:00high animals per square millimeter
  • 32:02that still don't benefit because there
  • 32:03are other mechanisms of resistance.
  • 32:05And I have and one of the interesting
  • 32:07topics that many labs are working
  • 32:09on including my own are what are
  • 32:11the mechanisms of resistance beyond
  • 32:12just not enough her to present.
  • 32:14And hopefully next year or a couple
  • 32:16years from now I'll come back to you at
  • 32:18grand Rounds and talk about mechanisms
  • 32:20of resistance and a more complex assay
  • 32:22that also doesn't just assay her too,
  • 32:25but maybe assays other biomarkers
  • 32:27that are associated with resistance.
  • 32:29Or other drugs.
  • 32:30And in fact the her two trope
  • 32:312 assay as well along its way.
  • 32:33So we can help clinicians decide
  • 32:36between Saskatoon Vova Tican,
  • 32:37which is a trope 2 targeting therapy
  • 32:41versus trastuzumab Drexel can.
  • 32:43So for that my my last slide,
  • 32:45overall HSR 2 assay is an LDT,
  • 32:47a lab developed test and not FDA approved.
  • 32:50So if you only do FDA approved tests,
  • 32:52you probably don't do them here
  • 32:53since most of our assays are LDT's,
  • 32:55but we do have a few FDA approved assays
  • 32:59and many FDA approved assays.
  • 33:01People don't realize this,
  • 33:02but being on the CAP
  • 33:03committees you realize this,
  • 33:04if you change one step of the
  • 33:06protocol of your FDA approved assay,
  • 33:08it is then an LDT and you must thus
  • 33:11validate it and so most assays.
  • 33:13We do are not FDA approved.
  • 33:15We might use FDA approved reagents,
  • 33:17but most assays we do are actually LDT's in
  • 33:19our lab and in all the labs around the world.
  • 33:22And that also applies for molecular assays,
  • 33:26gene mutation assays.
  • 33:27Many of those assays are also not
  • 33:29FDA approved assays but rather LDT's.
  • 33:32HSR 2 essay is in the correct dynamic range.
  • 33:35That is, we're not weighing elephants on or
  • 33:37weighing mice on a scale built for elephants.
  • 33:39The level of target required for trustees,
  • 33:41mab drugs decan is still unknown and
  • 33:43I speak here before you and I don't
  • 33:45want to try to hide that from you.
  • 33:46I think it's very clear that we don't
  • 33:48know the answer to this question yet.
  • 33:50But if we waited until we knew the answer to
  • 33:52the question before we started the essay,
  • 33:54we would be years behind as as this essay.
  • 33:56We've been working on this essay
  • 33:58for a couple years now to get it
  • 34:00to the point that it's at.
  • 34:01And so now that we have.
  • 34:03Tools, I am asked that oncologists in
  • 34:05the audience ask for measurements,
  • 34:07not for readings.
  • 34:08And please don't ask the pathologist
  • 34:10to change their minds.
  • 34:12That's persuasion Madison,
  • 34:13not precision medicine.
  • 34:15And we all respect our pathology
  • 34:16colleagues and I think we all,
  • 34:18you know,
  • 34:19I know that oncologists really think highly
  • 34:21of most of the pathologists they work with.
  • 34:23And I think that they don't realize
  • 34:25that when they do pursue persuasion
  • 34:28medicine that it's actually not
  • 34:29what the biologist wants to hear.
  • 34:31They don't want to be second guessed.
  • 34:33They want to if if if we're giving you
  • 34:35a reading, we're giving you a reading,
  • 34:37we really believe that's right.
  • 34:39And just like you shouldn't go back
  • 34:40on the test and change your answer,
  • 34:42don't change your answer.
  • 34:44It's if.
  • 34:45If that was your first impression,
  • 34:46it's probably your true impression
  • 34:48and probably your best reading.
  • 34:50And so with that,
  • 34:51I just want to thank the people
  • 34:52in lab that do all the work.
  • 34:53I get to talk about it,
  • 34:54but it's really a crew of people that do
  • 34:56all this stuff that I told you about.
  • 34:58I especially like to point out mirror
  • 35:00to Matafi who started that and started
  • 35:02building this essay in the lab over
  • 35:05two years ago now and then my Yale
  • 35:07collaborators and funding sources etcetera.
  • 35:09And then here's the the the key
  • 35:12group at our last holiday party,
  • 35:14our lab group Aileen has now left.
  • 35:16She was involved in a lot
  • 35:18of the analytic stuff.
  • 35:19Matt Lou helped out with some of the.
  • 35:20Analytic stuff as well.
  • 35:22And then and Jack and Katie
  • 35:24weren't at the party,
  • 35:25so they got their picture separate.
  • 35:27So with now, I've also left
  • 35:28about 20 minutes for questions,
  • 35:30if there are questions.
  • 35:31Thank you very much.
  • 35:40So we have 4 questions in the chat.
  • 35:43Maybe while you're warming up,
  • 35:44should I start with those?
  • 35:45Oh no, there's only two.
  • 35:46What about discordance with
  • 35:48pathologists reading the same
  • 35:49slides after a washout period?
  • 35:51So Manju Prasad,
  • 35:53a esteemed pathologist in our department,
  • 35:55asks a very pivotal question, that is.
  • 35:58When you're doing any kind
  • 36:00of pathologist study,
  • 36:01when you read it once,
  • 36:02if you're going to read it again,
  • 36:03you should have a washout period.
  • 36:04That is so you don't remember
  • 36:06that case because surprisingly,
  • 36:07pathologists have a really good memory for
  • 36:09what the morphology of cases look like,
  • 36:11and they can also remember the
  • 36:13patient's name on the label.
  • 36:14And so a lot of studies have
  • 36:16a washout period.
  • 36:17We didn't need a washout period in this
  • 36:19study because they only saw the slides once.
  • 36:21So if we're going to show them to them
  • 36:23again and if we're going to do any
  • 36:25kind of intra observer reproducibility,
  • 36:27which we didn't do and some
  • 36:29other studies have done,
  • 36:30we would need a washout period.
  • 36:31But in this case,
  • 36:32a washout period was not required.
  • 36:34And then Timothy Robinson asks,
  • 36:37is heterogeneity within
  • 36:38the tumor important issue?
  • 36:39Is it more important to do a small
  • 36:41percentage of cancer cells that
  • 36:42express a high amount of heart, too?
  • 36:43Or is it more important to know that
  • 36:45a high number of cells expressed at
  • 36:47least the minimum amount of her too?
  • 36:48Wow, phenomenal question.
  • 36:50That's Jax three, that's his.
  • 36:51Thesis project,
  • 36:52I think that's a great question.
  • 36:54We obviously don't know the answer.
  • 36:56All the pathologists in the audience
  • 36:57know that her two is very heterogeneous.
  • 36:59Not only is it heterogeneous
  • 37:01from within a slide,
  • 37:03but it's heterogeneous between cuts.
  • 37:05And all the pathologists in the audience
  • 37:06know that when we sample one core
  • 37:08biopsy that's less than 1% of the tumor.
  • 37:10And so there's no way for us to actually
  • 37:12answer that question about true
  • 37:14heterogeneity of the patients tumor.
  • 37:16But what we can add,
  • 37:17we can ask about heterogeneity
  • 37:18on the slide and we can and are
  • 37:21asking at that question.
  • 37:22That is,
  • 37:22how important is high expression
  • 37:24in a single cell versus high
  • 37:26expression in the average cell?
  • 37:28We started with the average.
  • 37:29You have to start somewhere,
  • 37:30and I don't know that the
  • 37:31average is a correct answer.
  • 37:33You could argue because of
  • 37:34the bystander effect of TDXD,
  • 37:36it's actually the highest ones
  • 37:38that make the most difference,
  • 37:40but we don't know that.
  • 37:41That's just speculation at this point.
  • 37:45Let's see. Now it's your turn.
  • 37:49It doesn't.
  • 37:51Say.
  • 37:55That's a great question.
  • 37:59We can do more.
  • 38:00So as soon as I had the assay built,
  • 38:02I applied for tissue from AstraZeneca
  • 38:05adicci senko from the Destiny 4 trial
  • 38:08and was rapidly told I would never see that.
  • 38:11And it's, I don't fault them for that.
  • 38:14They have their own people that
  • 38:16can do quantitative work and they
  • 38:19have an FDA approval for IHC 0123.
  • 38:21So they don't want to have to
  • 38:23change their FDA approval.
  • 38:24They're making a lot of money on this
  • 38:26drug and it would be detrimental to
  • 38:28the shareholders of that company to
  • 38:29have me have access to that tissue.
  • 38:34My question was how much heterogeneity
  • 38:37do you see in the ATOMAL expression?
  • 38:39Because you're taking so many fields of
  • 38:41view and taking an average, do you see
  • 38:43a lot of heterogeneity there or is it?
  • 38:46So that's a great question.
  • 38:49Heterogeneity within a core
  • 38:51biopsy is quite substantial.
  • 38:53And as you know when you read them,
  • 38:55you see bright areas and not so bright areas.
  • 38:57And you know how do we handle that?
  • 38:59Well, someday we'll know how you
  • 39:01know whether it's the highest sell or
  • 39:03the average sell or the lowest sell.
  • 39:06That's most important for response
  • 39:07to Trump drug seeking.
  • 39:09But we don't know that yet.
  • 39:10And so in the same vein of OK,
  • 39:13we're just going to take a core biopsy and
  • 39:15say that that represents the whole tumor,
  • 39:17we're going to just take the
  • 39:18average and say that that.
  • 39:19Represents the expression of her too.
  • 39:22And the second question
  • 39:23moved for the clinician.
  • 39:25We see situations with heterogeneity
  • 39:27where we have a clear 3 plus tumor where
  • 39:31the patient gets you know trastuzumab
  • 39:33and there's complete response and
  • 39:35there's another tumor which was her
  • 39:37to negative and was zero or you
  • 39:40know one plus which didn't respond.
  • 39:42So what will these patients benefit
  • 39:45from a second round of DXD or
  • 39:48when they have two distinct?
  • 39:52Her two profiles to maybe I can use the
  • 39:55microphone since there's 71 people online.
  • 39:58Yeah, when I but I, I do want
  • 40:00to clarify the question because,
  • 40:01I mean we wouldn't use.
  • 40:05We wouldn't have used a standard her
  • 40:07two therapy if they were one plus.
  • 40:13Why don't we choose?
  • 40:18Do we use her two therapy, I mean. Yeah.
  • 40:25But the patient?
  • 40:29Patient had complete response
  • 40:31to that through. So it was our CB0,
  • 40:34but then the tumor which was
  • 40:36one plus still extensive.
  • 40:39Yeah so I mean it depends
  • 40:41on the clinical situation.
  • 40:42We know pretty clearly now that with
  • 40:45before you know with the previous
  • 40:47generation of her two therapies that
  • 40:49you do not see any benefit with non
  • 40:51her 2/3 plus or amplified cancer.
  • 40:54So the her two lows do not respond
  • 40:55to the previous generation any of the
  • 40:57previous generation of her two therapies.
  • 40:59So but with now with Tristan Madrox
  • 41:01taken you know I think you could
  • 41:04you know make a case that you know
  • 41:06you might you would see potentially
  • 41:08could see benefit both.
  • 41:09And that clearly amplified in
  • 41:11the her two lows.
  • 41:12But prior to that we would look
  • 41:14at a case like that on a case by
  • 41:16case basis and say well let's use
  • 41:18the her two therapy to get rid of
  • 41:20that usually more aggressive her
  • 41:22two her two positive cancer and
  • 41:24then we'll worry about the her two
  • 41:26negative or her two low cancer later.
  • 41:28But it's it's you know again the
  • 41:30the field is evolving now that we
  • 41:32have these drugs that work across
  • 41:34different levels of her too.
  • 41:35I mean getting to in your earlier point
  • 41:37that the two questions were brought
  • 41:39up about her two heterogeneity and
  • 41:40I think that's really interesting.
  • 41:42Again with the first generation,
  • 41:44her two therapies, it was very clear.
  • 41:46We actually did a prospective,
  • 41:47big prospective trial with with the other,
  • 41:51the first antibody drug conjugate
  • 41:53that doesn't have bystander effect
  • 41:56and in that study a heterogeneous
  • 41:58cancer responded much work much less.
  • 42:01Effectively to a heterogeneous cancer
  • 42:02than it did to a non heterogeneous
  • 42:05cancer and and quantitatively that
  • 42:07the to your specific question what
  • 42:10mattered was the percent of her two
  • 42:12negative cells not the intensity
  • 42:15of her two on themselves.
  • 42:18Again with a drug that has bystander
  • 42:21effect as as I think David was alluding
  • 42:23to that might be switched and maybe
  • 42:25just if you just need to have a
  • 42:27certain number of her two strongly
  • 42:29positive cells to get the drug in.
  • 42:31And then the and then the bystander effect
  • 42:32will take care of the her two negative cells.
  • 42:34We like to test out
  • 42:35prospectively with we haven't.
  • 42:38Had the funding yet to do that trial.
  • 42:42Yeah. And I enjoy your talk, David.
  • 42:46Is any do you have any information?
  • 42:50The conjugate drug can get activated.
  • 42:54In the extracellular and
  • 42:56microenvironment of tumor cells.
  • 42:58So I I would again defer to Ian,
  • 43:01who's much more of an
  • 43:02expert on this than I am.
  • 43:03But it's my understanding that the drug,
  • 43:05once it comes off,
  • 43:06it has to be cleaved inside the cell.
  • 43:09But once it comes off,
  • 43:10it survives in the extracellular environment.
  • 43:13And that's how the bystander effect works.
  • 43:14That's how it can kill neighboring cells.
  • 43:16Bystander effect doesn't really require.
  • 43:20To go into the cells as long as it's a.
  • 43:25Present in the microenvironment of the
  • 43:28tumor cell in the enriched fashion
  • 43:31you you will have some activities.
  • 43:33Well the drug is an inhibitor
  • 43:35of topoisomerase,
  • 43:36so it has to get to the nucleus somehow.
  • 43:38I guess to have its effect
  • 43:40you can get activate.
  • 43:42Outside
  • 43:42of the cells. You don't have to take
  • 43:45anybody to go inside the cells.
  • 43:48Right, but that that that but
  • 43:50the antibody doesn't necessarily
  • 43:52take the the drug I guess can get
  • 43:54into cells without the antibody,
  • 43:55but the reason they conjugated to
  • 43:57antibodies so you can increase
  • 43:59the dose locally to the tumor.
  • 44:02Michael environment.
  • 44:03We have a more protease type.
  • 44:07To break up the linkage between
  • 44:11conjugate drug and the conjugate ohh,
  • 44:13that'd be fine.
  • 44:15That that that means you read that
  • 44:18could partly explain why the the
  • 44:23heterogeneity potential difficult
  • 44:25involvement as well as you may
  • 44:29have another interesting parameter
  • 44:31to assess now today with the.
  • 44:36Mass Effect. We could look into.
  • 44:40Whether they're saying reached?
  • 44:43Do you conjugate?
  • 44:45Drugs.
  • 44:45And in that case you would
  • 44:46argue that it worked.
  • 44:48It would work without trustors
  • 44:49maybe even being present.
  • 44:51You could you get the deconjugation
  • 44:53even if there's no target present.
  • 44:55That's that's why you get a negative.
  • 44:57Right without right without her two
  • 44:59present if if the if if it's a true her
  • 45:0220 the drug could still work because
  • 45:04it could get deconjugation and be effective.
  • 45:07Everywhere in the body.
  • 45:09Anywhere in the exercise room.
  • 45:12Have unreached.
  • 45:14That particular,
  • 45:15yeah,
  • 45:16I I think that you know,
  • 45:17the the question is the toxicity
  • 45:18then and that's actually the problem.
  • 45:20I didn't go into that.
  • 45:21But one of the problems with this
  • 45:22drug is it has pulmonary toxicity
  • 45:24and that patients get interstitial
  • 45:26lung disease about 10% of the time.
  • 45:28And that's another reason why
  • 45:29you need a companion diagnostic.
  • 45:31And one wonders if perhaps the
  • 45:33interstitial lung disease is due to extra,
  • 45:36you know,
  • 45:37extracellular environment cleaving the
  • 45:39drug even in the absence of her too,
  • 45:42although we've also found
  • 45:43that her two is present.
  • 45:45Normal Airways at about the level it is in,
  • 45:47low in low in about at about
  • 45:491/4 UN quote one plus level,
  • 45:51or between four and six
  • 45:53animals per square millimeter.