Exploiting Unexpected NAD Metabolic Vulnerabilities in PPM1D-mutant Gliomas

Transcript

• 00:00<v ->My pleasure to present our next speaker,</v>
• 00:02Dr. Ranjit Bindra, who is an Associate Professor
• 00:05of Therapeutic Radiology here at Yale School of Medicine.
• 00:10Dr. Bindra is a graduate of Yale School of Medicine,
• 00:12so we are very proud of that.
• 00:14And he received his MD and PhD in this program.
• 00:19And he has also completed his residency
• 00:21in Radiation Oncology at Sloan-Kettering Cancer Center.
• 00:25Since then he has come back home and has been
• 00:28an extremely successful and accomplished physician scientist
• 00:31with many discoveries that are now finding their way
• 00:33to clinic.
• 00:35Today, he is going to talk to us
• 00:37about how he's exploiting some metabolic vulnerabilities
• 00:42in glimoas that have a BMP1D mutation.
• 00:46I give you Dr. Bindra.
• 00:47Thank you very much.
• 00:49(applause)
• 01:04<v ->Okay, great.</v>
• 01:05Thanks a lot for having me today.
• 01:07I want to tell you about a really interesting
• 01:09recent story from our group looking at DIPG mutation
• 01:13and its effect actually on any de-metabolism.
• 01:16These are my disclosures which are not relevant today.
• 01:18We'll start off just with one slide
• 01:20really on sort of our approach to
• 01:22novel therapeutics development here at the cancer center.
• 01:25We'll then move on to the story
• 01:27of a DIBG-associated mutation in this gene called PPM1D
• 01:30and how it actually affects a NAD metabolism
• 01:33and leads to a clinically actionable target.
• 01:36Then if time permits, we'll cover a little bit
• 01:37about how we're trying to translate this
• 01:39directly into the clinic like we've done before.
• 01:43So, just getting started.
• 01:44We are very interested in bench to bedside
• 01:46discoveries and studies in our laboratory.
• 01:49And a lot of it starts with looking at the landscape
• 01:51of tumor-associated mutations
• 01:53like the ones that are shown here.
• 01:55We like to look at those mutations
• 01:57and figure out rapid and effective ways to model them,
• 02:00so often we'll use Cripsr Cast,
• 02:02but often we'll just use things like
• 02:03simple open reading frame expression
• 02:05just so we can get isogenic modeling of each one
• 02:07of these mutations.
• 02:09We then move those model cell lines
• 02:11into synthetic lethal screens.
• 02:12Often we'll combine them with DNA damaging agents as well.
• 02:16One of the unique things that we're very, very interested in
• 02:18is trying to find the sort of Achilles Heels.
• 02:21So trying to find driver mutations that may induce defects
• 02:24that we can then exploit for therapeutic gain.
• 02:26We then move towards more patient-derived,
• 02:29more relevant cell line models to validate the effects
• 02:32from our screens and our isogenic cell lines.
• 02:34And of course we have to move this
• 02:36into flank and in vivo type modeling
• 02:38before we can actually move this into clinic.
• 02:40And finally, as I've mentioned earlier,
• 02:42we're very interested in trying to drive our discoveries
• 02:44as quickly as possible,
• 02:45namely into Phase 1 and Phase 2 trials.
• 02:48Brain tumors being the bulk of our work,
• 02:50often we have drug delivery problems,
• 02:52and so often we'll look to folks
• 02:54like the Saltzman Laboratory to explore alternate methods
• 02:58to deliver some of these drugs into the brain.
• 03:00And we've been working for quite some time
• 03:02with Mark's group on nano-particle versions
• 03:04of some of the drugs that we're studying.
• 03:06So with that sort of backdrop,
• 03:07let me give you a little overview of this story.
• 03:10First we need to start with DIPG.
• 03:12This is a disease
• 03:13that I am actually relatively obsessed with
• 03:15having seen my first patient at Sloan-Kettering
• 03:18and watching that 3-year-old patient die
• 03:20was really touching for me.
• 03:21For the clinicians in the room,
• 03:23you know these films quite well.
• 03:25For the non-clinicians,
• 03:27this is an Axial T2 MRI,
• 03:29and then this is just to orient you
• 03:30for the non-clinicians.
• 03:32This is very, very devastating tumor
• 03:34here in the brainstem,
• 03:35which largely can be regarded as the Grand Central Station
• 03:38for the human body.
• 03:40And these tumors literally will take a child's life
• 03:43within about 2 years.
• 03:45Okay?
• 03:46And a picture is worth a thousand words,
• 03:48and so I often like to show the pictures of patients
• 03:49that we've lost in our clinic to this disease
• 03:52to understand that we need to do something better.
• 03:54This child lasted about 2 years.
• 03:56On average, a patient with DIPG in 1990 would live
• 04:00about 9 months.
• 04:01How are we doing?
• 04:03So in the last 20 years, we're still at about 9 months.
• 04:06It's actually quite depressing.
• 04:08And one of the things to note here is that biopsies
• 04:10in this disease are quite rare.
• 04:11This is a very difficult area to get tissue,
• 04:14and so much of the treatments were based
• 04:16on diagnostic MRI images, then with the assumption
• 04:20that these are just baby versions of adult gliomas.
• 04:24Once we began biopsying these tumors,
• 04:26folks like Chris Coley in Neurosurgery Pediatrics here,
• 04:29who did a lot of these biopsies when he was a fellow
• 04:31up in Boston, we suddenly realized
• 04:33that these were not adult tumors.
• 04:35These were very, very unique.
• 04:36The spectrum mutations were quite different.
• 04:38Some of you may recognize one of these mutations.
• 04:40This is a H3K27M mutation that's found in
• 04:44about 80 percent of DIPGs.
• 04:46This gene mutation
• 04:48profoundly affects chromatin structure
• 04:50and leads to enormous range of gene expression
• 04:52and changes in the cell.
• 04:54But a subset of these, these tumors also have the mutations
• 04:57in a phosphatase called PPM1D.
• 05:00So what's the role of PPM1D in DIPG?
• 05:02We'll get to that in just a moment.
• 05:04What I'll tell you is, over the last 10 years or so,
• 05:07there's no known role in epigenetic regulation for PPM1D.
• 05:11So just zooming in on this mutation.
• 05:13This is a phosphatase as I mentioned.
• 05:15And in 2014, so five years ago,
• 05:18Hyan and colleagues at Duke showed that
• 05:21these mutations cluster in the C-terminal domain.
• 05:24They're heterozygous, and they're activating.
• 05:25So they lead to a hyper stable version of this phosphatase.
• 05:29And interestingly, even though
• 05:31this gene was implicated in DIPG 5 years ago,
• 05:33we've known about this gene for actually about 20 years.
• 05:36Actually back in '97.
• 05:39This gene was also known as
• 05:40Wild-type p53-induced phosphatase 1.
• 05:44So these are the same gene.
• 05:46And these genes are actually implicated
• 05:48in things like breast cancer
• 05:50as well as ovarian cancer and neuroblast
• 05:52and medulloblastoma.
• 05:53The difference is that the gene is actually amplified
• 05:55in these cases versus a hyper stable activation
• 05:58via the heterozygous mutation here.
• 06:01So what do these mutations do?
• 06:04So PPM1D is actually involved
• 06:06in dephosphorylating the SQT motif modifications
• 06:10induced by ATM and ATR.
• 06:12And these are the types of proteinst that are targeted
• 06:15by PPM1D shown here.
• 06:16One of the most commonly or well-established
• 06:19targets is H2AX, so hyperactive PPM1D actually leads
• 06:24to an accelerated dephosphorylation of H2AX.
• 06:26So it's thought to in principle disrupt the DNA repair
• 06:29and DNA response.
• 06:31So from our perspective, for our laboratory,
• 06:34there's sort of a fork in the road.
• 06:35How do we target these mutations, right?
• 06:38So on one end,
• 06:39we could just block aberrant phosphatase activity, right?
• 06:41And so those that know our lab and IDH1 story,
• 06:43we don't like doing that, okay?
• 06:45And there are drugs that have been developed.
• 06:47Actually for the last 10 or 12 years,
• 06:49there's about 3 or 4 drugs that have been developed
• 06:51that simply block the phosphatase activity.
• 06:53Most of them are not drug-like,
• 06:55none are in clinical trials,
• 06:57and overall they haven't been that effective
• 06:59as an anti-tumor strategy for tumors
• 07:01that have these types of mutations.
• 07:03So we're, again, very interested
• 07:04in exploiting Achilles Heels,
• 07:06or tumor-associated defects,
• 07:09hopefully by DNA repair given the role of this
• 07:12mutation in DNA repair.
• 07:15So with that, entered our first graduate student
• 07:17in the laboratory several years ago, Nate Fons.
• 07:19And Nate set out to model the PPM1D mutation,
• 07:22and to simply ask a question
• 07:23whether we could do a drug screen
• 07:24with an isogenic cell lines.
• 07:26So it actually took him about a year and half
• 07:28to make this model, and this is shown here.
• 07:31This is a truncated activated form.
• 07:32We targeted that C-terminal domain
• 07:35where the DIPG mutations are found.
• 07:37And you can see this hyper activated, or
• 07:39of high levels of expression by western blot.
• 07:41And he did all the things a good grad student should,
• 07:43which is looked at protein stability and confirmed indeed
• 07:46that this is a hyper stable form of the protein.
• 07:49And he did funcuatzie these to show
• 07:51that this mutation was active in the sense that
• 07:54post-IR could get an accelerated de-phosphorylation of H2AX,
• 07:57and this was dependent upon PPM1D activity
• 08:00because treatment with a PPM1D inhibitor
• 08:02abolished that effect.
• 08:03And this is just a FOSI example shown here.
• 08:06Then Nate, after about a year and a half,
• 08:08or 2 years or so, went on to do a screen,
• 08:10and we used the platform that we developed
• 08:12to find the IDH induced PARP sensitivity
• 08:15that some of you heard me talk about before.
• 08:17This is a 96 well plate medium throughput
• 08:19viability screen that we developed.
• 08:22And we were super excited
• 08:23because our idea was that we were going to essentially get,
• 08:26IDH impairment sensitivity,
• 08:29PPM1D hyperactive dis-regulation of DNA repair,
• 08:32that we would get another hit in that class.
• 08:34So Nate looked at about 100 DNA repair inhibitors
• 08:36and DNA damaging agents.
• 08:38And to our surprise, we found nothing,
• 08:41which that was always really stressful
• 08:42when it's your first graduate student,
• 08:43and that's their screen after 2 years, right?
• 08:45So it's a tough thesis meeting.
• 08:47However, it turns out that we had one extra row
• 08:52in the 96 well plate.
• 08:53I just love telling this story
• 08:55because it's sort of the story of how academia often
• 08:58operates.
• 08:59We had one extra row, and I was actually doing the plating
• 09:02back in the day and the folks in my lab just said
• 09:04remind that I was in the laboratory, and
• 09:06I actually had plated, we had one extra row
• 09:08and we put in some NAMPT, a NAMPT inhibitor row
• 09:12based on a paper by Dan Cahill up in Boston.
• 09:14He had shown that IDH mutations,
• 09:16again our laboratory is very interested in those,
• 09:18those mutations as well.
• 09:19He had shown that IDH mutations confer sensitivity
• 09:22to the NAMPT inhibitors
• 09:24via this NAD depletion phenotype.
• 09:26And this is the drug we added to this, this set of plates.
• 09:29Oddly enough, that was the only hit in our screen,
• 09:32which was very surprising to us.
• 09:34So what is NAD, and what are NAMPT inhibitors?
• 09:37This is a pathway.
• 09:38Again, when we worked on the IDH stuff,
• 09:40we actually had to relearn the citric acid cycle,
• 09:42and here we had to learn about NAD
• 09:44during the course of this work.
• 09:46And this is the NAD sort of cycle,
• 09:48and there's multiple different ways to generate NAD
• 09:51which is sort of the central currency of life
• 09:53in a metabolizing cell.
• 09:55And so the first thing we did was actually just
• 09:58cold called a guy named Charlie Brenner.
• 09:59He's out at Iowa, and he discovered a very, very
• 10:02critical pathway in the NAD biosynthetic pathway.
• 10:06And we called and we said
• 10:08we've got this very odd
• 10:09PPM1D induced NAMPT inhibitor sensitivity,
• 10:12can you help us out?
• 10:13And just to orient folks,
• 10:14NAMPT is a critical player in the NAMPT salvage pathway
• 10:18that essentially regenerates NAD and it's
• 10:22blocked by these drugs called NAMPT inhibitors.
• 10:25So just sort of Cliff notes, and again,
• 10:26aging myself by using Cliff notes
• 10:28because I know about 90 percent of the audience
• 10:30does not know what these are.
• 10:31Nut these were very, very useful
• 10:33before the days of Google.
• 10:34And so NAMPT inhibitors are interesting drugs.
• 10:37There's actually a diverse range of drugs out there.
• 10:38They're highly potent.
• 10:40They've actually been tested in Phase 1 and 2 trials.
• 10:43There's still a few
• 10:44drugs that are being tested.
• 10:46Most have actually been shelved
• 10:47because there really is no biomarker.
• 10:49There's actually a lot of toxicity
• 10:50in the face of limited efficacy.
• 10:53So with that sort of backdrop,
• 10:54Nate went on to probe this interaction further.
• 10:57He first ruled out any clonal artifact from CRISPR,
• 11:00and he showed a multiple CRSPR clones that
• 11:02we had very nice NAMPT sensitivity in the PPM1D mutants.
• 11:05He then showed it was a class specific,
• 11:07not just a drug effect.
• 11:09He showed that with multiple, structurally unique
• 11:11NAMPT inhibitors that we could still get
• 11:13mutant PPM1D induced differential sensitivity.
• 11:16And then as I mentioned earlier,
• 11:17we had the activating truncating mutations
• 11:20as well as the amplifications.
• 11:21He went on to show that over expression
• 11:23of both full-length or truncated PPM1D could also
• 11:27recapitulate the NAMPT sensitivity.
• 11:29Uh, in contrast, a catalycally inactive version of PPM1D
• 11:33was unable to confer NAMPT inhibitor sensitivity.
• 11:35So we then sent ourselves to Charlie Brenner's developed,
• 11:39high resolution NAD metabolic profiling platform.
• 11:43And he sent us back some intriguing data
• 11:45in that really all the NAD precursors were suppressed.
• 11:49And at base line you can see here Wild site
• 11:51versus the PPM1D mute.
• 11:52You can see base line, uh, depressed levels.
• 11:54When you treat with a NAMPT inhibitor,
• 11:56then you get critically low levels of NAD
• 11:59which we believe is contributing to the loss
• 12:02of viability in those cells.
• 12:04So then zooming in on this.
• 12:06We worked with Charlie, uh, to sort of probe
• 12:10the mechanistic basis for this phenomenon.
• 12:12Charlie suggested that we start repleting or rescuing,
• 12:16with various precursors.
• 12:17Adding NAM, adding NR, and adding NA to test the integrity
• 12:21of each of these pathways.
• 12:22Okay?
• 12:23So, these are synergy or antagonism plots
• 12:26that I'm showing you right here.
• 12:27So, this is the drug NAMPT inhibitor,
• 12:28and then this is the NAD precursor that we're adding.
• 12:31Red indicates an antagonistic effect,
• 12:34essentially showing that that pathway is intact.
• 12:37Okay?
• 12:37So adding NAM you can see then bypasses the effect
• 12:40of the NAMPT inhibitor,
• 12:41so that pathway essentially was intact.
• 12:42Adding NR, his favorite NAD precursor
• 12:46also led to antagonism.
• 12:48But the one intriguing result
• 12:50was shown here on the left.
• 12:51When you add NA,
• 12:53we're unable to antagonize,
• 12:54suggesting the defect in this pathway to converge
• 12:56with NAMN which is mediated by this protein called NAPRT.
• 13:01In parallel, Nate then did a siRNA screen
• 13:03knocking down each one of these drugs
• 13:06to see which one would phenocopy the PPM1D mutation
• 13:09causing NAMPT inhibitor sensitivity.
• 13:11And he found one gene target of interest.
• 13:14And indeed that was NAPRT,
• 13:16and that's shown here in the orange.
• 13:18We then rushed back to our cell lines and asked the question
• 13:21well, what is the status of NAPRT expression
• 13:23in these cell lines?
• 13:24Maybe there's a problem with it.
• 13:25And to our surprise,
• 13:26in all of the lines that had engineered a PPM1D mutation,
• 13:29they had lost NAPRT expression under these conditions.
• 13:33We then went ahead and said
• 13:35well is NAPRT loss accounting for the NAMPT sensitivity?
• 13:38So he over expressed NAPRT in the PPM1D mutant cells,
• 13:42and that's shown here in the blue bar,
• 13:43so they completely rescue the effect.
• 13:45So this is really being driven by loss of NAPRT.
• 13:49(throat clearing)
• 13:50We then moved again in our process flow
• 13:52to patient-derived models which obviously are more relevant
• 13:53to the human situation.
• 13:55And we got some patient-derived
• 13:573D DIPG cultures from Michelle Monje out at Stanford.
• 14:01And you can see here again in the mutant PPM1D
• 14:04cultures shown here that we had loss of NAPRT.
• 14:07So we could recapitulate,
• 14:08we could see this also in patient-derived models,
• 14:11and that led to profound sensitivity to a NAMPT inhibitor.
• 14:14And that's shown here, and again,
• 14:15just by eying these 3D cultures, it's quite striking.
• 14:19Working with Ranjini our fearless lab manager in the lab,
• 14:22we developed a PPM1D mutant flank zenograph model.
• 14:26And then we also showed
• 14:27that this effect could be recapitulated in vivo
• 14:30in this flank model shown here.
• 14:33Now narrowing in on the mechanism.
• 14:35So we ask,
• 14:36well the protein is down so what exactly is happening?
• 14:38This is not thought to be an epigenetic modifier,
• 14:40this mutation.`
• 14:41But could this be possible?
• 14:43So here's a Tacksman analysis of MRI transcript levels.
• 14:46You can see here we have reduction of, uh, of NAPRT levels,
• 14:49in our PPM1D mutant engineered and patient-derived lines.
• 14:53We then went and did a series of ChIP Assays
• 14:56at pretty comprehensive panel looking at the promoter,
• 14:58which I won't show you today that suggested that
• 15:00there was some sort of repressive effect of the promoter.
• 15:03And then more importantly,
• 15:04we showed that there was elevated 5 methylcytosine
• 15:06directly at the NAPRT promoter.
• 15:08And this is just a methyl-dip assay.
• 15:10Again, just glossing over this because of time.
• 15:12But this really suggested to us that
• 15:14the promoter's actually being silenced
• 15:16by mutant PPM1D.
• 15:19So we sought to probe this a little bit deeper,
• 15:22and I'll show you just a little smattering of the,
• 15:24of the data that, uh, we've gotten more recently.
• 15:26Uh, so we brought in a bioinformatics group
• 15:28and did whole methylene profiling to understand
• 15:30whether this was focal or global.
• 15:33Uh, we actually expanded our patient-derived line.
• 15:35There's sets of lines.
• 15:35There's actually only a handful of PPM1D mutant DIPG lines
• 15:39in the world, and we are able to get them.
• 15:41And then we sort of looked and asked the question
• 15:43of whether this was a specific, uh, NAPRT promoter specific,
• 15:47or a global methylation, uh, phenotype.
• 15:50Uh, so we brought in the folks from TGEN.
• 15:51We've been working with Mike Berens for quite some time,
• 15:53and asked them to join.
• 15:55And then we reached out to folks across the pond,
• 15:57namely Chris Jones and the Carcaboso Lab,
• 15:59who some of these PPM1D patient-derived models
• 16:02for some of our work.
• 16:04What we first soun- what we first found looking at 850K,
• 16:08whole methylene in profiling is shown here.
• 16:10You can see in this red for the beta values,
• 16:13that largely the PPM1D mutants had a focal,
• 16:16dense hyper methylation of the NAPRT promoter.
• 16:19And actually when you look at global methylation profiling,
• 16:21you can see that on average, again,
• 16:23yellow are the mutant lines.
• 16:24You can see this cluster of methylation targets,
• 16:28essentially a CPG island like methylene phenotype
• 16:31that we're seeing in the PPM1D mutants.
• 16:33Again, we're seeing this both in the patient-derived lines
• 16:36as well as in our engineered lines in this systems.
• 16:39So just sort of our working model.
• 16:41This was just published about two weeks ago
• 16:42in Nature Communications.
• 16:44What we're finding is that elevated PPM1D activation
• 16:47leads to silencing of NAPRT likely in the context
• 16:50of a CPG island like methylene phenotype,
• 16:52which in activates this press handler salvage pathway
• 16:55essentially silencing NAPRT leading to the depletion of NAD
• 16:58and a setup, essentially a metabolic vulnerability
• 17:02for treatment with NAMPT inhibitors.
• 17:04There's a lot more work to be done here,
• 17:06and because of time, I won't go into those questions,
• 17:08but this work is really just beginning for us.
• 17:11Bringing it now back to IDH1, so some of you know
• 17:13some of the adult midline supratentorial gliomas
• 17:17have IDH mutations.
• 17:18And there's a really an intriguing leak, link
• 17:21between PPM1D and IDH1.
• 17:22I alluded to this earlier from the Dan Cahill work
• 17:25that actually prompted us to serendipitously
• 17:27sort of make this discovery.
• 17:29And what, what Dan and colleagues actually found was
• 17:31similarly in IDH mutants as well,
• 17:34they silence NAPRT leading to an NAD depletion.
• 17:37So we don't understand why adult and pediatric tumors
• 17:39with these mutations are silencing
• 17:43this pathway, but there's clearly a theme
• 17:45across all age groups for these tumors for NAD depletion.
• 17:50So in the last just 5 minutes or so,
• 17:52I'll tell you about what we're doing to get this
• 17:53into the clinic.
• 17:55So as many of you know we are very interested
• 17:57in trying to drive some of the work that we do
• 17:58into patients as soon as possible.
• 18:00And this is work that I think
• 18:03many of you seen us present, and this is work
• 18:04from the Glazer Lab, Stephanie Halene's lab, Morokinaw,
• 18:07and my laboratory, essentially mapping out
• 18:10this oncometabolite-induced brachinist
• 18:12that leads to NAPRT sensitivity.
• 18:13And so we've done this before,
• 18:15and we've been able to translate this work
• 18:16into multiple clinical trials shown here.
• 18:18And really a testament to the cancer center,
• 18:21namely folks like, uh, Pat Lorusso, Paul Eder,
• 18:24Asher Marks, Toma Tebaldi, and again Stephanie Halene
• 18:27to really drive this into our patients.
• 18:30So the questions for this were how we're going to get this
• 18:33into the clinic, recognizing some of these huge caveats
• 18:38that I'm going spend the last few minutes on.
• 18:40So first of all, there are a number of barriers
• 18:42to a systemic NAMPT inhibitor trial, uh, in DIPG
• 18:45that we'll touch upon in a moment.
• 18:47We would love to consider combinations
• 18:49with both radiation and chemotherapy
• 18:51because we don't think monotherapy for any of these,
• 18:53these aggressive gliomas is going to be sufficient.
• 18:56And I'll tell you a little bit about some surprising
• 18:58results about the blood brain barrier penetration
• 19:00of some of the drugs that are out there.
• 19:03So just a few, uh, few points on the first 491 00:19:04.957 --> 00:19:07.370 the first question.
• 19:07So, as I mentioned, multiple NAMPT inhibitor trials
• 19:11have been initiated and closed.
• 19:13Most of them ended with lack of efficacy,
• 19:15and pretty significant doxylamine toxicity.
• 19:18A lot of folks would say that the
• 19:21lack of efficacy was simply that these were solid tumor
• 19:23Phase 1 trials with no biomarkers.
• 19:25They were not trying to find for any specific
• 19:28biomarker that could confer sensitivity.
• 19:30And the liabilities in particular were
• 19:33hemologic and retinal toxicity
• 19:35which have really spooked a lot of folks that are,
• 19:37are developing NAMPT inhibitors at the moment,
• 19:40and they've shelved them.
• 19:41This is just one paper to show you an example of,
• 19:43of this finding.
• 19:45So, in parallel to that,
• 19:47we'd love to explore the concept of combining this
• 19:50with other clinically relevant regimens for glioma,
• 19:53namely DIPG.
• 19:54And it turns out as many of you know in the audience here,
• 19:57temozolomide is a mainstay of brain tumor treatment.
• 19:59And temozolomide itself actually has been shown
• 20:02to cause an NAD depletion by metabolic stress.
• 20:05In parallel, what about things like radiation,
• 20:07another mainstay for DIPG and other gliomas?
• 20:10And I do apologize for I rat out colleagues I know
• 20:12to quote a paper from 1978.
• 20:14I promise I'm going to get a more recent one.
• 20:17But it turns out that radiation actually depletes
• 20:18NAD levels as well.
• 20:19And so where am I going with this?
• 20:21We, we have now NAMPT inhibitors,
• 20:23possibly radiation temodar - those are, that's like the,
• 20:25the stupe trial plus NAMPT inhibitor -
• 20:27so an opportunity for what I would call tri-modality
• 20:30synergy with NAMPT inhibitors.
• 20:32So we're really excited about possibly incorporating
• 20:34these modalities into a future clinical trial.
• 20:37So the last little point,
• 20:38again I just want to give you a flavor for this
• 20:40because of time.
• 20:40There's a lot more to it.
• 20:42What about CNS penetration?
• 20:44So, one thing we learn is that your drug is no,
• 20:46no better than how well it can get into the blood,
• 20:49past the blood brain barrier for glioma trials.
• 20:52Turns out that most NAMPT inhibitors
• 20:53are CNS impermeable.
• 20:55The ones that are permeable actually have
• 20:57that retina toxicity that I mentioned earlier.
• 21:00So this is a bit of a conundrum.
• 21:02And so one thing that we're interested in looking at
• 21:04is Convection Enhanced Delivery.
• 21:05Some of you may this, may know of this approach
• 21:07where you directly inject a drug into the brainstem
• 21:10or into the brain to bypass the blood brain barrier.
• 21:13Folks like Joe Piepmeier and colleagues, uh, have p -
• 21:15have done pioneering work in this field.
• 21:17And believe it or not, this is actually now,
• 21:19now quite common.
• 21:20There's probably about 7 or 8 trials in kids and adults
• 21:23testing CED of novel agents.
• 21:26Uh, we would argue that this is a great idea,
• 21:27but we know within a few hours those drugs you inject,
• 21:30they wash right away.
• 21:31Um, and so if the way to encapsulate those drugs
• 21:34in some sort of particle, i.e. nano-particle,
• 21:37we could then find a way to prolong, uh, the deliv-
• 21:40the drug delivery and exposure in the tumor.
• 21:42So who could we got to for that?
• 21:44Well, of course we could go right across the street
• 21:45to Mark Saltzman.
• 21:46And Mark and Jianbing Zhou and folks have,
• 21:49have really done pioneering work
• 21:50in developing brain penetrating PEG and related
• 21:54nano-particles and have shown in
• 21:57some really seminal papers including this one in PNAS,
• 21:59that you could use them to treat gliomablastoma.
• 22:02So we've been working with Mark for quite some time.
• 22:04So some of you know over the last couple years
• 22:07we've had a very, a long fruitful collaboration.
• 22:09We've actually shown by proof of concept
• 22:11that we could take DNA repair inhibitors,
• 22:13like ATR inhibitors, uh, and encapsulate them
• 22:15in nano-particles and use them to treat, gliomas.
• 22:17And this is just one of our papers that came out recently.
• 22:21So that's actually exactly what we're doing now
• 22:22for NAMPT inhibitors.
• 22:23And this is actually a YCC co-pilot grant
• 22:27looking at whether we can capsulate NAMPT inhibitors
• 22:29in nano-particles.
• 22:30And this is work from Yazhe Wang and Jason Breckta,
• 22:33radunct resident in my laboratory showing that
• 22:35yes, we can and that these particles effectively can
• 22:38release drug and actually deplete NAD
• 22:41in this setting.
• 22:43So just to wrap up here in the last 2 minutes.
• 22:45So, we really are firm believers that
• 22:48metabolic vulnerabilities can be exploited
• 22:49in both adult and pediatric gliomas.
• 22:51We've shown this for IDH in the adults,
• 22:53and now we're showing for PPM1D in the kids.
• 22:55We believe that just like IDH,
• 22:57and we're trying to translate this into the clinic.
• 23:00We're really falling up as fast as we can
• 23:04to understand why PPM1D mutations
• 23:06are inducing NAPRT silencing.
• 23:08And, we do believe that there's an opportunity
• 23:11here to take existing treatments like radiation and temodar
• 23:14and bring in NAMPT inhibitors into the fray.
• 23:16And we're very actively exploring
• 23:18whether CED and nano-particles may address
• 23:20some of the issues that I've talked about earlier.
• 23:23So with that I'll just wrap up.
• 23:24I'll thank all the folks that did the work
• 23:26in the laboratory, and all of them are shown here
• 23:29at our recent retreat.
• 23:30Nate has moved on.
• 23:31He's now our first, first grad student,
• 23:33and now a post-doc at the NCI.
• 23:35And of course I'd like to thank the folks that
• 23:37fund this work as well.
• 23:38And we have time for a few questions.
• 23:39(applause)