Skip to Main Content

Targeting Oncometabolite-induced DNA Repair in Cancer

October 04, 2021

Yale Cancer Center Grand Rounds | September 28, 2021

Dr. Juan Vasquez

ID
6952

Transcript

  • 00:00Everyone for attending this week's
  • 00:02grant Yo Council Center grand rounds.
  • 00:05It's my privilege and pleasure to introduce
  • 00:08Dr Juan Vasquez for this this week talk.
  • 00:12Dr Vasquez is an assistant
  • 00:14professor of Pediatrics.
  • 00:15He received his medical degree
  • 00:16from Brown University and a Master
  • 00:18of Health Science from Yale,
  • 00:19where he also completed his fellowship
  • 00:22in Pediatric Hematology Oncology.
  • 00:23His clinical focus on the
  • 00:25care of children with cancer,
  • 00:26particularly solid tumors,
  • 00:28as reachers research,
  • 00:29is focused on the development
  • 00:31of immunotherapy.
  • 00:32For pediatric tumors,
  • 00:33particularly malignant brain tumors,
  • 00:35he's interested in characterizing
  • 00:36the immune landscape of pediatric
  • 00:38brain tumors and understanding
  • 00:39the interplay between DNA repair
  • 00:41and anti tumor immune response.
  • 00:43One is been an embedded assistant
  • 00:45professor in our laboratory for a
  • 00:47little over two years now and is
  • 00:49really hit the ground running as
  • 00:51rapidly approaching independence.
  • 00:53On that note, he did recently receive his KO,
  • 00:55a career development grant to
  • 00:57fund this project,
  • 00:58which will be talking about today.
  • 00:59So with that I will let one take.
  • 01:02Take the show away.
  • 01:08Great thank you Ranjit Saunders
  • 01:10Commissioner my screen here.
  • 01:29All right? Can you see my screen OK?
  • 01:34Great. Alright, so thank you again.
  • 01:36It's a real honor to be able
  • 01:38to present for you today.
  • 01:39An uncle metabolite induced
  • 01:41repair DNA repair defects.
  • 01:43Uhm? I've got no disclosures.
  • 01:47So today I'll briefly review some
  • 01:50background on Uncle Metabolite
  • 01:52induced DNA repair defects,
  • 01:54which really was established by the
  • 01:56seminal work of my research mentor.
  • 01:58Doctor Ben drove heard from as well as
  • 02:01Doctor Peter Glaser here at Yale and in
  • 02:04collaboration with Brian Shuck at UCLA.
  • 02:06Also present some of our work on
  • 02:08targeting DNA damage response pathways
  • 02:10and uncle metabolite producing tumors.
  • 02:13And then lastly,
  • 02:13I'll touch a bit on the potential
  • 02:15for exploiting these uncle
  • 02:16metabolite induced DNA.
  • 02:17Repair defects in order to promote an
  • 02:20inflammatory tumor microenvironment
  • 02:21and potentially synergized with
  • 02:23immune checkpoint blockade.
  • 02:29So just as a very brief reminder,
  • 02:32the Krebs cycle is very important in
  • 02:34cellular energy production and alpha
  • 02:36ketoglutarate is a is a key intermediate
  • 02:38in the Krebs cycle and Alpha Ketoglutarate
  • 02:41dependent dioxygenase is regulate a
  • 02:43number of key cellular processes.
  • 02:45Mutations in enzymes of the Krebs cycle
  • 02:47result in an excess accumulation of two
  • 02:50hydroxy glutarate succinate and fumarate,
  • 02:52and I'll go through these in
  • 02:54more detail in the coming slides.
  • 02:56But in general,
  • 02:57these uncle metabolites competitively
  • 02:59inhibit alpha ketoglutarate dependent
  • 03:01dioxygenase is by virtue of their structural
  • 03:04similarity there by dysregulating AKI,
  • 03:07variety of downstream cellular processes and
  • 03:09resulting in prolonged congenic signaling,
  • 03:12and this is really why there are
  • 03:14classified now is uncle metabolites.
  • 03:17So focusing first on IDH mutations
  • 03:20or isocitrate dehydrogenase so IDH
  • 03:23catalyzes the oxidation oxidative
  • 03:25decarboxylation of isocitrate
  • 03:27producing alpha keto glutarate.
  • 03:29Uhm, and these heterozygous IDH
  • 03:31mutations result in a new amorphic
  • 03:34activity of that enzyme whereby
  • 03:36alpha ketoglutarate is then further
  • 03:38converted into two hydroxy glutarate.
  • 03:41And most commonly are missense
  • 03:44arginine to histidine mutations.
  • 03:46Make up about 70% of all these
  • 03:48mutations and you can see IDH
  • 03:50mutations in a variety of tumors.
  • 03:51Most most commonly in low grade gliomas
  • 03:54and secondary GBM's as well as AML and
  • 03:58chondrosarcoma and cholangio carcinoma.
  • 04:02Further on down to the Krebs cycle
  • 04:04succinate dehydrogenase catalyzes the
  • 04:05oxidation of succinate to fumarate
  • 04:08and fumarate hydratase catalyzes
  • 04:10the hydration of fumarate to malate
  • 04:12germline heterozygotes loss of
  • 04:14function mutations in these genes
  • 04:16are associated with a predisposition
  • 04:17to cancer formation thought to act
  • 04:20through a two hit hypothesis whereby
  • 04:22tumors have loss of heterozygosity,
  • 04:24leading to excess accumulation
  • 04:26of femur and succinate.
  • 04:28Germline FH mutations predispose
  • 04:30to hereditary leiomyoma ptosis
  • 04:31and renal cancer syndrome.
  • 04:33And germline SDH mutations predispose to
  • 04:36succinate dehydrogenase related hereditary
  • 04:39paraganglioma and pheochromocytoma
  • 04:40as well as renal cell carcinoma.
  • 04:43And, importantly,
  • 04:44renal cell carcinoma in the setting
  • 04:45of both these syndromes is typically
  • 04:47aggressive with a high propensity to
  • 04:49present with metastases early in disease
  • 04:51and once these patients metastasize,
  • 04:52very limited treatment options exist.
  • 04:56So, as I mentioned before,
  • 04:58this is a field really pioneered
  • 05:00by Doctor Benjamin, Dr.
  • 05:01Glaser and former grad
  • 05:03student portal Cylkowski,
  • 05:04and a series of high impact publications
  • 05:07where uncle Metabolites were found
  • 05:09to inhibit homologous recombination
  • 05:11and confer prohibit or sensitivity.
  • 05:14So I'm just going to very
  • 05:15briefly summarize this work,
  • 05:17but what they found is uncle
  • 05:19metabolites inhibit alpha ketoglutarate
  • 05:21dependent histone lysine demethylase
  • 05:23is KTM 4 AMB leading to a Baron
  • 05:26hypermethylation of histone 3,
  • 05:28lysine 9 or HK H3K9 at loci
  • 05:32surrounding DNA breaks.
  • 05:34So they used a really elegant double
  • 05:36strand break chip seek assay,
  • 05:38in which you can see that control cells
  • 05:41there's a spike of H3K9 trimethylation.
  • 05:44That induced double strand breaks
  • 05:46followed by a coordinated recruitment
  • 05:48of double strand break repair factors.
  • 05:50However,
  • 05:50in cells with an uncle metabolite
  • 05:53succinate fumarate and two HG,
  • 05:55there is H3K9 trimethylation
  • 05:57already present at the site before
  • 05:59induction of double strand breaks,
  • 06:01and this really serves to mask
  • 06:03that local trimethylation signal
  • 06:04that's important for triggering
  • 06:06proper recruitment of homologous
  • 06:08recombination proteins,
  • 06:09essentially leading to defective
  • 06:10HR and a bracken NIST phenotype.
  • 06:15So now just to very briefly and generally
  • 06:17introduce the topic of synthetic lethality.
  • 06:20So as you can see here from this figure,
  • 06:21part is really an important enzyme
  • 06:25involved in the repair of single strand
  • 06:27breaks during basic scission repair.
  • 06:29Pop inhibition and results in impaired
  • 06:32based excision repair and converts
  • 06:34single strand then single strand
  • 06:36breaks are converted to double strand
  • 06:38breaks in the in the process of
  • 06:40cellular replication in cells with
  • 06:41an intact homologous recombination.
  • 06:43This DNA damage is effectively
  • 06:44repaired and you have cell survival.
  • 06:46However, in the setting of an HR deficiency,
  • 06:49there's a buildup or accumulation
  • 06:50of unrepaired DNA damage,
  • 06:52ultimately leading to cell death and this
  • 06:53is this idea of synthetic lethality.
  • 06:57So this same synthetic lethality was
  • 06:59found also in the setting of uncle
  • 07:01metabolite induced DNA repair defects.
  • 07:03So just looking at just a snippet
  • 07:05of that data you can see here in the
  • 07:08isagenix model and he LA cells with IDH,
  • 07:10wildtype and I DH R132H mutant.
  • 07:15There's an increased amount of
  • 07:16baseline unrepaired DNA damage,
  • 07:18and this is as measured through a
  • 07:20common tale essay where damaged DNA.
  • 07:23As its nucleus informs US, Comet tail,
  • 07:25which is his representative unrepaired
  • 07:27DNA damage and you can see that IDH
  • 07:30mutant Tumors Harbor an increased
  • 07:32amount of damage at baseline.
  • 07:34Uh, additionally looking here
  • 07:35at a clonogenic survival assay,
  • 07:37you can see that these cells,
  • 07:40these IDH mutant cells have more
  • 07:42sensitivity to irreparably than
  • 07:43their wild type counterparts,
  • 07:45and the same was seen in in vivo.
  • 07:48A study using HTTR human cancer
  • 07:50colon cancer cell line with an
  • 07:53IDH mutation where these tumors
  • 07:54were sensitive to PARP inhibition,
  • 07:57leading to delayed tumor growth.
  • 08:02Similarly, in a subsequent study,
  • 08:04a similar DNA repair defects and
  • 08:06corporate hipper sensitivity were
  • 08:08shown in FH and SDH deficient models.
  • 08:11So looking here now at a collection of human.
  • 08:15Tissues, let's see.
  • 08:18You can see that again compared
  • 08:21to normal tissues.
  • 08:22Those with SDHB mutations in FH
  • 08:24mutations have an increased amount
  • 08:26of baseline DNA repair damage.
  • 08:28I mean sorry baseline DNA damage
  • 08:29and then here looking at a FH
  • 08:31deficient PDX model you can see in
  • 08:33vivo there's delayed tumor growth
  • 08:35with a different park inhibitor.
  • 08:37Here bnes 673.
  • 08:44Based on these findings,
  • 08:45clinical trials have been started,
  • 08:47including here at Yale,
  • 08:48so this is just a report from
  • 08:50our Phase one group here,
  • 08:51showing that there's a subset of
  • 08:53patients with IDH mutated solid tumors.
  • 08:55In this case, chondrosarcoma is that
  • 08:56derives clinical benefit from elaborate,
  • 08:58cheap, elaborate treatment with some
  • 09:00patients showing either stable disease,
  • 09:02or in this case, highlighted here,
  • 09:05partial remission of their tumor burden.
  • 09:09And obviously these trials are continuing
  • 09:11to recruit patients in our ongoing.
  • 09:16Switching now to to our work looking at
  • 09:19targeting DNA damage response pathways
  • 09:22and uncle metabolite producing tumors,
  • 09:25we turned our attention here so we so we
  • 09:27know that monotherapy is unlikely to be
  • 09:29curative and in the majority of patients.
  • 09:31So we set avenues for exploring other
  • 09:33DNA repair pathways that could be
  • 09:35targeted in a combinatorial fashion.
  • 09:37So we turn to the ATR pathway shown here.
  • 09:40So in the setting of DNA damage
  • 09:43ATR phosphorylates, check one.
  • 09:44Which intense intern sets off a cascade to
  • 09:47coordinate several important cell functions,
  • 09:50including the arrest of cell cycle by
  • 09:53activation of intra S and G2M checkpoints.
  • 09:55This allows DNA repair to occur effectively,
  • 09:58and prevents premature mitotic entry
  • 10:00in the setting of ATR inhibition.
  • 10:02Damaged cells are allowed to
  • 10:03proceed past the S phase checkpoint,
  • 10:05thereby promoting the induction of double
  • 10:08strand breaks, premature mitotic entry,
  • 10:10and ultimately, cell death.
  • 10:13As you can see here.
  • 10:16So this is a work led by an
  • 10:18excellent postdoctoral associate,
  • 10:19that term retool,
  • 10:20and as you can see from the
  • 10:22clonogenic survival graph here,
  • 10:25IDH mutant cells were more sensitive
  • 10:27to a combination of a leopard
  • 10:29and the ATR inhibitor Azd 6738.
  • 10:32Compared to the wild type counterparts.
  • 10:35And similarly, in vivo,
  • 10:38using again HCT xenograft flank model,
  • 10:40you can see that the combination
  • 10:43of of a Labrador department,
  • 10:45her elaborate and ATR inhibition resulted
  • 10:47in significantly delayed tumor growth.
  • 10:52Just to get an idea of what mechanisms
  • 10:54might be underlying decided toxicity.
  • 10:56We then assessed for DNA damage as
  • 10:58measured by gamma H2X flow side in
  • 11:01these wild type and mutant cells after
  • 11:04treatment with elaborate is ATR inhibitor
  • 11:07or combination therapy and what you see
  • 11:09is that after 24 hours of treatment,
  • 11:10IDH mutant cells had significantly
  • 11:12increased proportion of damage to X foci
  • 11:15relative to the wild type counterparts,
  • 11:18suggesting increased level of unrepaired
  • 11:20DNA damage after drug treatment.
  • 11:23As I mentioned before,
  • 11:24ATR also plays an important role in
  • 11:27regulating cell cycle progression
  • 11:28in the setting of DNA damage.
  • 11:29So we assessed for the mitotic cell
  • 11:32population looking at phosphorylated
  • 11:33histone 3, which is a marker of mitosis,
  • 11:36and you can see again that with the
  • 11:39combination treatment you see an increase
  • 11:41amount of cells entering mitosis.
  • 11:42So the the idea here is that in the setting
  • 11:45of increased DNA damage and IDH mutant cells,
  • 11:48when you add ATR inhibition,
  • 11:49these cells progressed
  • 11:50through their cell cycle,
  • 11:51enter enter mitosis.
  • 11:52Prematurely and leading to cell death.
  • 11:57Again, turning out to the clinic,
  • 11:59there's actually trials now
  • 12:00ongoing of this combination,
  • 12:02including here at Yale,
  • 12:03where there's a phase two trial,
  • 12:04looking at elaborate and ATR inhibitor
  • 12:07Azd 6738 in the setting of IDH,
  • 12:10even solid tumors.
  • 12:11So we're looking forward to seeing the
  • 12:13results of this in the coming years.
  • 12:18So turning now to the other Krebs cycle
  • 12:20mutations I mentioned before, succinate
  • 12:22dehydrogenase and fumarate hydratase.
  • 12:25So in this study done in collaboration
  • 12:27with Doctor Shep, who's now at UCLA,
  • 12:29he's a urologic cancer surgeon.
  • 12:31We wanted to identify other potential novel
  • 12:33treatment approaches that exploit this uncle
  • 12:36metabolite induced genomic instability
  • 12:38using renal cell carcinoma models.
  • 12:40So here we turned our attention to.
  • 12:45Missoula made, which is an alkylating
  • 12:47agent that mediates its cytotoxic effects
  • 12:49by attaching methyl groups to DNA and
  • 12:51the repair of the N7 methyl guanine adduct.
  • 12:54In particular is needed by mediated
  • 12:56by the base excision repair pathway
  • 12:58in a process that involves park.
  • 13:00Therefore,
  • 13:00we hypothesize that apartment habisch
  • 13:03and will enhance Tim Assamite
  • 13:05induced city toxicity and FHN SDH
  • 13:07deficient renal cell carcinoma models.
  • 13:14To investigate this, we engineered
  • 13:18isagenix FH1 and SDHB knockout cells,
  • 13:21and for this we use the rank a cell
  • 13:24line rank is a pretty well established
  • 13:27mirroring renal adenocarcinoma model
  • 13:29that's derived from balb C mice.
  • 13:32So first by Western blot we
  • 13:34confirmed FH1 and SDHB knockout.
  • 13:37We then also further functionally
  • 13:39validated this knockout using
  • 13:41LCMS or liquid chromatography.
  • 13:43Mass spectrometry to look for
  • 13:44buildup of these uncle metabolites
  • 13:46succinate in fumarate,
  • 13:47respectively, and found that indeed,
  • 13:49our CRISPR mediated knockout does lead
  • 13:51to build up of these uncle metabolites,
  • 13:54as one would expect.
  • 13:56We next performed a seahorse assay
  • 13:58to measure oxidative phosphorylation
  • 14:00and found that again, as expected,
  • 14:02SDHB and FH1 loss of function and the
  • 14:05subsequent Krebs cycle dysfunction
  • 14:07that comes from that leads to
  • 14:09decreased oxidative phosphorylation.
  • 14:12So this helps sort of validate our model.
  • 14:15Next,
  • 14:15we sought to assess the intrinsic
  • 14:17DNA repair capability of Krebs
  • 14:19cycle deficient cells by looking at
  • 14:22markers of DNA damage at baseline.
  • 14:24So here again we turn to phosphorylated
  • 14:26gamma HTX as well as 53 BP,
  • 14:29one which are markers of unrepaired
  • 14:31DNA damage and the cellular response to
  • 14:33DNA double strand breaks, respectively.
  • 14:35We found that similar to our
  • 14:39previous work looking at.
  • 14:42C and A's deficient human tissues we see
  • 14:46an increased amount of baseline DNA repair,
  • 14:49unrepaired DNA damage in the knockout cells
  • 14:51compared to the wild type counterparts,
  • 14:54and as measured by the full site.
  • 14:56Here,
  • 14:56you can see these are the damage
  • 14:58to expose and read and hear the
  • 14:5953 BP one in green.
  • 15:03Next we tested for the ability of
  • 15:05the chemical might of tomorrow
  • 15:07night to potentiate the in vitro
  • 15:10activity of PARP inhibitor BGB 290.
  • 15:13So in this clonogenic survival
  • 15:15assay here cells were treated with
  • 15:18a dose of B GB 290 ranging from
  • 15:20one micromolar to 10 micromolar.
  • 15:22In this, in the presence or absence
  • 15:25of 15 micro molars at Tim's Olamide,
  • 15:27so appear. These two lines.
  • 15:29Here BG be alone and here is with
  • 15:31combined to Missoula might as well.
  • 15:34And what you can see again is that both
  • 15:36in SDHB knockout cells and FH knockout cells,
  • 15:39there's an increased cytotoxicity
  • 15:41with combination and Tim is Olumide.
  • 15:50Lastly, we tested for the in vivo
  • 15:52efficacy of combination treatment,
  • 15:54and these SDH be deficient
  • 15:57rank of flank models.
  • 15:59Of note, one thing that's interesting
  • 16:00here is that in terms of clinical
  • 16:02experience with the combinations of
  • 16:04PARP inhibitor and Thomas Olumide,
  • 16:05which has been tried and
  • 16:07not setting up other tumors,
  • 16:09one of the the limitations of
  • 16:11these trials has been increased.
  • 16:13Set of toxicity with full dose
  • 16:15combination of both of those.
  • 16:17And so typically for in vivo studies.
  • 16:20That is, all my dose is anywhere
  • 16:22between 25 milligrams per kilogram
  • 16:23to 50 milligrams per kilogram
  • 16:25per dose which translate to human
  • 16:27equivalent dose of about 75 to
  • 16:30150 milligrams per meter squared.
  • 16:32So here we were interested to see if
  • 16:34we could find some anti tumor effect
  • 16:37at lower doses of Tim's Olumide.
  • 16:39Which might limit some of those
  • 16:41toxicities so for this study we
  • 16:43used Tim Alumite at three milligrams
  • 16:44per kilogram per dose,
  • 16:46and and did indeed find that even
  • 16:48at such lower doses of temozolomide
  • 16:50we find delayed tumor progression.
  • 16:53And importantly, there were no.
  • 16:55There was no increased toxicity
  • 16:57with the combination treatment,
  • 16:58at least as measured by animal body weight.
  • 17:04So based on this we can say
  • 17:07that the band FH1 knockout Cells
  • 17:09Harbor and increased levels of
  • 17:11unrepaired DNA damage at baseline,
  • 17:13and that the combination of pop
  • 17:15inhibitor Intimes Olamide enhances set
  • 17:16of toxicity in these cells in vitro,
  • 17:18and that the combination with low
  • 17:20dose temozolomide led to delayed
  • 17:22tumor growth in vivo as well.
  • 17:26And turning now to the
  • 17:28clinical setting again.
  • 17:29We recently had an interesting case within
  • 17:31our own department within our own section.
  • 17:33This is a patient cared for by one
  • 17:35of my colleagues Dr pushing car
  • 17:37and this is a patient with GIST
  • 17:40and PARAGANGLIOMAS in the setting
  • 17:42of a germline SDHB mutation.
  • 17:45This is a patient that progressed
  • 17:46through multiple lines of treatment,
  • 17:47including imatinib than that in as well
  • 17:50as a heat shock protein phase one trial.
  • 17:53And so at this point,
  • 17:55having progressive multiple lines of
  • 17:57treatment doctor pushing car up to trial.
  • 18:00Cycles of elaborate with Tim's Olumide.
  • 18:03And this is off any clinical trial.
  • 18:06As you can see here from the pet images.
  • 18:08These are the pretreatment images showing
  • 18:11multiple liver metastatic nodules as
  • 18:14well as Bony lesions along the spine.
  • 18:16And after six cycles,
  • 18:19this patient had a.
  • 18:21Partial remission in remission of all the
  • 18:24Bony lesions as well as partial remission,
  • 18:26multiple liver nodules as well.
  • 18:30Of course this is just anecdotal.
  • 18:33This is an anecdotal case,
  • 18:34so there are trails about
  • 18:36clinical trials currently ongoing,
  • 18:38including a phase two trial that's
  • 18:40currently in development and soon to open,
  • 18:43led by our collaborator Dr.
  • 18:44Shuck at UCLA,
  • 18:46and in this trial they'll be testing
  • 18:49combinations of 290 and low dose
  • 18:52temozolomide in the setting of patients
  • 18:54with refractory or recurrent renal
  • 18:57cell carcinoma that is at FH deficient.
  • 19:05Lastly, I just wanted to touch
  • 19:06a little bit on my work,
  • 19:08focused more on the immune aspects
  • 19:10of Uncle metabolite and DNA repair
  • 19:12defects and potential for leveraging
  • 19:13these defects in order to promote an
  • 19:16inflammatory tumor microenvironment
  • 19:17and even potentially desensitized
  • 19:19to mean checkpoint blockade,
  • 19:21which I know is a topic near and dear to
  • 19:24the heart of many folks on this call.
  • 19:27So as folks on this audience,
  • 19:29I'm sure already acutely aware of only
  • 19:31a subset of patients really benefit
  • 19:32from immune checkpoint blockade and
  • 19:34some of the markers of response
  • 19:36that have been described relate both
  • 19:38to tumor increase amount of tumor
  • 19:41associated mutations and subsequent
  • 19:43neoantigen load as well as a more
  • 19:46inflammatory tumor microenvironment.
  • 19:50So with this in mind,
  • 19:51a lot of attention has really been paid
  • 19:53lately to the role of DNA damage response,
  • 19:54and specifically DNA repair defects
  • 19:56and mediating the tumor immune
  • 19:58microenvironment in response to
  • 20:00immunotherapy and the general idea.
  • 20:01Again, just very generally speaking,
  • 20:03is that the there's a potential in
  • 20:05the setting of DNA repair defects
  • 20:07when you treat these these tumors
  • 20:09with additional DNA damaging agents
  • 20:11that you have an increased number
  • 20:13of mutations and subsequently
  • 20:14increased number of neoantigens
  • 20:16that can be recognized by T cells.
  • 20:18The other sort of a main train of thought
  • 20:21is that these DNA damaged DNA repair.
  • 20:25Defects can also serve to
  • 20:27activate the innate immune system,
  • 20:29for example through activation
  • 20:30of the C gas sting pathway,
  • 20:32which is a double stranded
  • 20:34DNA sensing pathway.
  • 20:36Of course there are now multiple
  • 20:37pathways that are described in
  • 20:39terms of innate immune activation,
  • 20:40including recognition of
  • 20:41double stranded RNA sensing,
  • 20:43which a lot of folks here at Yale
  • 20:44have been working on as well.
  • 20:45But since we're working talking mainly
  • 20:48about double stranded DNA damage,
  • 20:50our focus has mainly been on
  • 20:52the C guesting pathway.
  • 20:55So, as I mentioned before for for
  • 20:57this study we utilized the SYNGENEIC
  • 20:59ranking model and this is a model
  • 21:02that has been characterized before
  • 21:03as being minimally responsive
  • 21:05to immune checkpoint blockade,
  • 21:07and this is our own experiment here,
  • 21:08confirming that at least the
  • 21:09wild type version of this cell
  • 21:11is pretty unresponsive to PD1,
  • 21:12which allows us to to sort of use this
  • 21:15as a model to see if we can increase
  • 21:18sensitivity to immune checkpoint blockade.
  • 21:20And again, this is a very preliminary,
  • 21:23but we've we've been starting to
  • 21:24really explore the immune effects
  • 21:26of these crab cycle mutations,
  • 21:27so this is again a an early experiment
  • 21:29where we performed bulk sequencing
  • 21:31just in the cells looking at wild
  • 21:34type versus knockout cell models.
  • 21:36And there's definitely a differential
  • 21:37gene expression.
  • 21:38But one thing I just want to
  • 21:40characterize a point out here in
  • 21:41terms of a related to the immune
  • 21:43effects of these mutations.
  • 21:45As you can see that one of the
  • 21:47top hits for both of these in the
  • 21:49knockout cells is an increased
  • 21:50expression or upregulation of
  • 21:53the antigen presenting pathways.
  • 21:55We've followed this up with a
  • 21:57separate study looking actually
  • 21:59now at single cell sequencing
  • 22:00and this is just so far had been
  • 22:02done in our SDHP knockout cells,
  • 22:04and thankfully we confirmed SDHP
  • 22:06knockout as we we already did using other
  • 22:09methods and again we see differential
  • 22:12gene expression patterns between
  • 22:13well tape and SDHP knockout cells.
  • 22:15And again this is with work that's been
  • 22:18done and help with help from Doctor Sule.
  • 22:21Interestingly,
  • 22:22we see here as well that the knockout cells
  • 22:26seem to upregulate beta 2 microglobulin,
  • 22:29which I'm sure folks or where is
  • 22:30an important component will is is
  • 22:32a component of the MHC class one
  • 22:33molecule and is really required
  • 22:35for antigen presentation,
  • 22:36and there's been a lot of great
  • 22:38work from folks here at Yale to
  • 22:39show that made it two microalbumin
  • 22:41losses is one of the markers of
  • 22:43immune checkpoint resistance.
  • 22:46We also then went on to look
  • 22:48at differential gene expression
  • 22:49with PARP inhibition and and so
  • 22:51we looked at treatment after we
  • 22:53looked at single cell sequencing.
  • 22:55After 24 hours of treatment
  • 22:57and and what we found so far.
  • 22:58And this is still work in progress and
  • 23:00we're still looking through this data,
  • 23:01but one of the things we've seen
  • 23:03is an increased expression after
  • 23:0424 hours of the labyrinth,
  • 23:06specifically in the knockout cells
  • 23:08with upregulation of interferon
  • 23:10induced protein protein 44,
  • 23:12which is one of the interferon stimulated
  • 23:14genes that has been associated with an.
  • 23:16Interferon related DNA damage signature.
  • 23:19We also saw upregulation of stat one
  • 23:22with elaborate treatment and those
  • 23:24SDHB knockout cells and stat one.
  • 23:26The Jack stat.
  • 23:27One pathway has been shown to be
  • 23:30important for interferon stimulated
  • 23:32gene expression and has been
  • 23:34shown to play a role in mediating
  • 23:37amino therapy response.
  • 23:38So these are interesting.
  • 23:40Sort of very preliminary data
  • 23:42and and gives us a direction to
  • 23:44look for as we go forward.
  • 23:46I also again performed.
  • 23:49Some flow cytometry,
  • 23:50and this is now just looking at the
  • 23:53tumor cells after implantation and
  • 23:54what we see here is that in the SDHB
  • 23:58knockout cells there's an increased
  • 24:00proportion in terms of the percentage
  • 24:02of live cells that are CD3 positive
  • 24:05and of those CD 3 positive cells.
  • 24:07There's an increased proportion that have
  • 24:09PD one expression within the SDHP knockout,
  • 24:11so again very preliminary.
  • 24:13But this is sort of exciting
  • 24:16data to follow up on for us.
  • 24:20Uhm?
  • 24:20Now I will turn to the other part of
  • 24:23our talk from earlier the IDH mutations
  • 24:27because this is also an area that
  • 24:29I'm interested in is not to mention
  • 24:31that have an interest in in the glioma,
  • 24:33tumor immune microenvironment
  • 24:34and have performed some studies
  • 24:36previously looking at that.
  • 24:37So I was really interested
  • 24:38to develop an idea.
  • 24:39Each mutant syngeneic model to allow us
  • 24:42to to explore this a little bit further.
  • 24:46So traditionally the the main
  • 24:48model that's been used for the main
  • 24:50syngeneic model that's been used
  • 24:52for looking at glioma response to
  • 24:54immune checkpoint blockade has
  • 24:55been the steel 261 model which is
  • 24:58chemically induced line with a
  • 24:59moderate degree of immunogenicity
  • 25:01at baseline and as you can see,
  • 25:03this is our own experiment in our
  • 25:05own hands and it goes in line with
  • 25:07previous research that shows that this
  • 25:09about 50% of mice with field to six.
  • 25:11One tumors will respond to anti PD,
  • 25:13one blockade and as a lot of
  • 25:14folks here on this.
  • 25:15So I will know that really doesn't
  • 25:17recapitulate the human experience where,
  • 25:18unfortunately so far clinical
  • 25:20trials looking at I mean checkpoint
  • 25:22blockade in GBM have been have
  • 25:24not shown really much benefit.
  • 25:26So we were hoping to find a model
  • 25:27that maybe might be a little
  • 25:29more translationally relevant,
  • 25:29understanding the limitations that
  • 25:31we're working with that we have to sort
  • 25:33of rely on these syngenetic models.
  • 25:35So we turned to our collaborator
  • 25:36Dale Carter at UCSF,
  • 25:38and his group developed this SB 28 line,
  • 25:41which is a genetically engineered line that.
  • 25:44They've already characterized,
  • 25:45and they found that more more closely
  • 25:48mimics the poorly immunogenic human gliomas,
  • 25:51and so this is a line that.
  • 25:53Intends to have low T cell infiltration,
  • 25:56high number of tumor associated
  • 25:58macrophages and more immunosuppressive
  • 26:01micro micro environment and these
  • 26:03tumors do not really respond to even
  • 26:05dual blockade with PD one and C TL A4.
  • 26:08They've also characterized this line
  • 26:09in terms of the mutational burden.
  • 26:11Showed that again SB 28 cells have a much
  • 26:14lower mutational burden these GL261 line.
  • 26:16So we hope that perhaps this is
  • 26:18this will be a little more of a
  • 26:20translationally relevant model as we go
  • 26:22forward looking at the immune effects.
  • 26:24So in terms of developing this as
  • 26:26an IDH mutant model, specifically,
  • 26:27we've we've used a stable transfection
  • 26:30with an R132H open reading frame,
  • 26:32and again characterized that there
  • 26:34is an expression of the R 138,
  • 26:36two H mutation as well as accumulation
  • 26:38of two hydroxy glutarate.
  • 26:40We've also characterized the in vivo
  • 26:45intracranial growth kinetics of this
  • 26:47model and shown that these IDH mutant
  • 26:51cells form tumors effectively and
  • 26:54characterize the survival with the
  • 26:55IDH mutation. In these in this model.
  • 26:59Again,
  • 26:59we further characterized in vivo as well,
  • 27:01and not just in vitro that in vivo.
  • 27:03These tumors maintain their expression
  • 27:05of the art 132 H mutation seen here
  • 27:08is through the immunohistochemistry
  • 27:10with this rust brown stain here,
  • 27:12as well as again through LCMS looking
  • 27:14for accumulation of two hydroxy glutarate
  • 27:17and tumor tissue and seeing an increase
  • 27:20accumulation in the R132H tumors.
  • 27:24So I really want to take this as
  • 27:25a in terms of future directions.
  • 27:27This is really the the the main project
  • 27:29that my K8 was funded for and I want
  • 27:32to really investigate the impact of
  • 27:33uncle metabolites on both cancer cell
  • 27:35intrinsic immune signaling as well
  • 27:37as the tumor immune microenvironment.
  • 27:39And I want to explore the immunomodulatory
  • 27:41effects of DNA damage response inhibitors,
  • 27:43such as ATR inhibitors in the setting
  • 27:46of uncle metabolite producing tumors
  • 27:47or really extending the findings we've
  • 27:49already had in our flank models to see
  • 27:51how this works in the tumor microenvironment.
  • 27:55I also want to investigate synergistic
  • 27:56interactions between the mean checkpoint
  • 27:58blockade and DNA damage response inhibitors,
  • 28:00and these uncle metabolite producing
  • 28:01tumors and hope to get started on
  • 28:03these preclinical studies in the
  • 28:04next in the upcoming months.
  • 28:08So with that I'll end up and I want
  • 28:10to just thank Doctor Bindra again,
  • 28:12who's my primary mentor and has
  • 28:14really been instrumental in in me,
  • 28:16sort of advancing and receiving my K-8 as
  • 28:18I build my pathway towards independence,
  • 28:20as well as all the members of the
  • 28:22Bingil lab have been instrumental
  • 28:24in helping me sort of progress,
  • 28:26as well as all those folks specifically
  • 28:28who helped with the projects I outlined.
  • 28:30I also want to thank Dr Shuck and his
  • 28:33lab at UCLA, and my many advisors here.
  • 28:36You know, only a few of which.
  • 28:38They're listed here as well as to
  • 28:39all my funders, so thank you again.
  • 28:43Thanks so much. One,
  • 28:44that was a wonderful talk and I
  • 28:46know we're a little bit over but we
  • 28:48don't have a second speaker so if
  • 28:49there are any burning questions,
  • 28:51feel free to put them in the chat.
  • 29:11Crystal clear. You know,
  • 29:14I'll start with one question I might
  • 29:17have missed this of the DDR inhibitors
  • 29:19that you want to look at to combine,
  • 29:22possibly with PD one in the setting
  • 29:24of IDH mutants are is there a
  • 29:26wish list of the DDR inhibitors
  • 29:28they would want to combine?
  • 29:30Maybe you could put one of them
  • 29:32in particular synergized in the
  • 29:34in tablet producing backgrounds.
  • 29:36I mean I think the ATR inhibitors
  • 29:38are really an interesting area to
  • 29:40explore and one that really hasn't
  • 29:41been looked at too much in terms
  • 29:43of the immune effects of these and.
  • 29:44It sort of makes sense conceptually,
  • 29:46that in the setting of these cells
  • 29:48entering sort of premature mitosis,
  • 29:50you'd have a lot of formation
  • 29:52of these micronuclei that could
  • 29:53activate the CSC gas sting pathway.
  • 29:55So certainly I think again, you know,
  • 29:57based on our initial work with Rita
  • 29:59and her findings in the flank model I,
  • 30:02I really want to pursue this more
  • 30:03and see if we can see signs of immune
  • 30:06activation and synergy with PD1 blockade.
  • 30:10Where to ask one more question.
  • 30:11Then we will close up if no others.
  • 30:13Any plans to write up that
  • 30:15wonderful case study with Farzaneh.
  • 30:18We've talked about it and yes,
  • 30:19I would love to know,
  • 30:20so I definitely want to check more
  • 30:22about that because I think that would
  • 30:23be a nice corollary to the you know,
  • 30:25as you know, the aranka work we're
  • 30:27hoping to write that up soon and
  • 30:29submit that as a manuscript.
  • 30:30So I think it would be a
  • 30:32great corollary to that.
  • 30:32So I definitely hope to write that up.
  • 30:35Wonderful,
  • 30:36well this is great.
  • 30:36We had a great turn out today and I
  • 30:38think you just answered everyone's
  • 30:39questions with your slides.
  • 30:40So thanks everyone for joining
  • 30:42us and have a great rest of
  • 30:44your Tuesday thank you room.
  • 30:47Take care bye bye.