IDEAYA Biosciences Inc

NASDAQ:IDYA

Earnings Call Transcript 2021-Q4

[Operator]

Good day and welcome to the IDEAYA Biosciences IDE397 Preliminary Clinical Data Update Conference Call. Today’s conference is being recorded. At this time, I would like to turn the call over to Yujiro Hata, CEO, IDEAYA Biosciences. Please go ahead

[Yujiro Hata, Chief Executive Officer & President]

Good morning, everyone. I'll be making some forward-looking statements today. And today we're absolutely thrilled to provide a program update on IDE397, as well as our Q1 2022 earnings update. Full year-end 2021 has been an absolutely transformational year for the company. We've been able to advance two programs in the clinic, as well as make significant progress across two additional late stage pre-clinical programs in PARG and PARP data. As part of this key advancement across our portfolio, today we'll be giving an additional update on the IDE397 Phase 1 dose escalation program. Before we begin, I wanted to thank all of the employees of IDEAYA and our partner GSK for its contributions to the IDE397 program, both through our IDEAYA GSK MAT2A joint development committee, as well as the broader joint steering committee. GSK has been a phenomenal partner and an invaluable in advancing our thinking on this program from both a monotherapy and combination development perspective. We also thanks GSK for its review and approval of the presentation materials we will share today. The focus of today's IDE397 program update will be specifically on the data required to complete the GSK option data package, which includes key pre-clinical pharmacodynamic data, clinical PK, clinical adverse events, and clinical plasma and tumor pharmacodynamic data. At the end of this session, we will have an open Q&A session with our analysts. And we do ask for the portion of IDE397 to keep the scope of the questions to be within the data categories and what's enclosed in this presentation. And that is the content that has been reviewed and approved by GSK under our partnership agreement. In terms of the agenda for today, I will first start with providing a high level profile on the GSK option data package requirements and a high level overview of the collaboration economics. Next, Dr. Matt Maurer, Head of Clinical Oncology will provide a walkthrough on the Phase 1/2 clinical development plan, the protocol amendment that has been submitted to the FDA to enable both the monotherapy expansion phase as well as the clinical combination initiation for this program. Next, Matt will provide an overview of the clinical pharmacokinetic data, as well as the favorable clinical adverse event profile that we've referred today. After that, Dr. Michael White, our Chief Scientific Officer will provide a walkthrough of the IDE397 pharmacodynamic data, including a very robust data set around the pre-clinical tumor pharmacodynamic data, as well as the clinical plasma and tumor pharmacodynamic data. And then lastly, a PK/PD analysis, as well as projected clinical efficacy time, the pre-clinical projections to our clinical, both pharmacodynamic pulmonary data. And then at the end, I will provide a summary of the presentation today as well as next steps for this program. And then we'll transition to the next phase of the presentation. You can get a summary from our Q1 2022 our earnings update, which Paul Stone, our Chief Financial Officer will walk through. Moving on to the next slide, on slide 3. This is a summary of the GSK option data package, both in terms of timing and scope of the data supporting the GSK opt-in decision. And as noted earlier, today's clinical data update on IDE397 will be focused on these key parameters and data categories that are required under our agreement for the option data package. In terms of pre-clinical data, the contents include, both non-clinical safety, Pharmacokinetic data and Pharmacodynamic data, as well as in-vivo efficacy. This data package is now complete and is being uploaded currently to the online data room. Next, the clinical data requirements for the [indiscernible] option data package of GSK is safety and tolerability data, Pharmacokinetic data and Pharmacodynamic data, both including plasma, as well as tumor Pharmacodynamic data. Based on where we are in the dose escalation, which we are currently enrolling Cohort 6, we are targeting expansion for the monotherapy expansion phase in mid year 2022. In addition, based on where we are on the assembly of the data package through GSK, we also anticipate that we will deliver the option data package to GSK mid year 2022. If GSK exercises it’s option, there will be a $50 million option exercise fee due subject to HSR clearance. If GSK likes to opt-in, the cost split would modify to an 80%, 20% cost share, with GSK responsible for 80% of the cost moving forward and IDEAYA for 20%. Next, there will be a set of milestone payments that could be potentially due, including $465 million in development and regulatory milestones, as well as $475 million sales milestones. In addition, we have retained 50-50 US profit splits, as well as ex-US high single digit to sub-teen double digit percentage royalty. We believe this partnership structure with GSK in this scenario of opt-in is highly value accretive for our shareholders and enables a very cost efficient fashion to advance this program in the clinic. So with that, I will now pass it along to Dr. Matt Maurer, our Vice President Head of Clinical Oncology to go through the next phase of this presentation. Matt, I will pass on to you.

[Matt Maurer, Head, Clinical Oncology]

Yeah. Thanks, Yujiro. So in this slide, you can see the sketch of the 397 development plan showing a comprehensive approach to proof-of-concept evaluation of both monotherapy and combinations that are supported by our preclinical evaluations. [indiscernible] strategy provides multiple shots on goal and optimizes their probability of uncovering transformational opportunities that can be rapidly brought to registrational follow up studies. The tumor types of main interest include non small cell lung cancer and Esophagogastric carcinomas for both monetary testing as well as in combination with Taxanes. These choices were based upon our preclinical monotherapy activity, as well as the high unmet medical need and larger addressable MTAP deleted populations. It should be noted MTAP deleted cancers have a relatively poor prognosis and do not respond well to immunotherapy, given that they're generally cold tumors and thus require novel therapies. You can see that for each tumor type we were combining with the standard of care Taxane, Docetaxel for lung and Paclitaxel for Esophagogastric. We and others have validated preclinical combinatorial activity with MEK inhibition and taxanes, and thus are excited about the prospect of clinical benefit. In addition, we have monotherapy basket cohorts for exploration across other tumor types and an opportunistic evaluation of another combination partner in which we have demonstrated preclinical synergy. We are targeting lots of expansion and combination testing in the middle of this year. Next slide. Shown on this slide are representations of our preclinical pharmacokinetic data. Key points to highlight are the well behaved steady state concentrations over time curves in the left panel and dose-proportional increase in exposure shown as fold-increases on the right panel. We are most excited about the ability to deliver dosing that has reached our target efficacious exposures based on preclinical data. Dose Cohort 5, which is in our target range, has been cleared in preliminary tolerability and we are currently enrolling into Cohort 6 where the first patient has cleared the DLT period. You can see the normalized relative fold increase in exposures across a 20 fold range. IDE397 shows flat and consistent temporal PK profiles across doses, with a low Cmax to Cmin ratios. In short, the favorable PK profile supports an acceptable clinical dosing regimen. Next slide. And this slide provides a bit more detail on the safety experience, thus far among the patients created through cohort five. The panel on the right shows the number of patients that have experienced growth related adverse events, per investigator broken out by grade. The side effect profile so far has been manageable, with low grade GI events and mild thrombocytopenia that have not affected dosing. Specifically, dose related use occurring in greater than 10% of patients include low grade nausea, decreased appetite, diarrhea, dehydration, and thrombocytopenia. There has been only been only one drug related Grade 3 event of asthenia. There had been no drug related SAEs or dose limiting toxicities to date. We believe these data set the drug up for appropriate monotherapy testing, as well as a therapeutic window useful for combination testing. This emerging safety profile also compares favorably to prior drugs targeting PRMT5 and MAT2A, which were limited by either hematologic or Lipitor toxicities. So with that, I'll pass it over to Mike to walk through some preclinical data, as well as our clinical PD data.

[Michael White, Chief Scientific Officer]

Thank you, Matt. Good morning, everyone. I’ll take a few minutes to walk you through our preclinical and clinical pharmacodynamic biomarker data. The key pharmacodynamic markers for the IDE397 program are directly related to the mechanism of action underpinning the MAT2A synthetic lethal interaction with MTAP deletion. As illustrated in this schematic on the left, upon MTAP deletion, which happens in 15% of solid tumors, the cellular MTAP substrate, MTA accumulates and partially inhibits the essential enzyme PRMT5 in tumor cells, which is hit one of this pairwise synthetic lethal opportunity. The MAT2A inhibitor IDE397 reduces the availability of cellular SAM which PRMT5 needs to activate splicing factors via symmetric dimethylarginine modification SDMA, that's hit two. So this one-two punch selectively disrupts essential pre-mRNA splicing in MTAP deleted tumors. You can see that in action on the right, no inhibition of SDMA accumulation in MTAP wild type cells, even with high doses of IDE397 and strong suppression of SDMA accumulation in MTAP deleted cells even at low doses. Notably as shown on the far right, the disruption of essential splicing in MTAP-deleted cancer cells by IDE397 is equivalent to that observed with direct SAM competitive PRMT5 inhibitor. In contrast, IDE397 has very limited activity in MTAP wild-type cells, consistent with synthetically full mechanism. The same can't be said for the PRMT5 inhibitor, which strongly perturbs mRNA splicing in all cells. So given this mechanism of action in patients on trial, we follow drug dependent methionine inhibition by measuring the concentration of SAM in plasma, that's our peripheral PD. And we met -- and we follow the extent of inhibition of PRMT5 by measuring the abundance of SDMA in cancer cells from tumor biopsies. That's our tumor PD. So on the next slide, please you draw. In Slide 8, you can see in preclinical tumor models and in patient biopsies, we measure tumor SDMA by immunohistochemistry with an anti-SDMA antibody. In our workhorse, preclinical MTAP-deleted lung cancer model on the left, we validated dose dependent reduction of tumor SDMA by IDE397 with complete inhibition of tumor SDMA and tumor growth by 30 milligrams per kilogram. That same dose extinguished tumor SDMA across a subset of MTAP deleted patient derived xenograft models, as shown on the right, demonstrating the methionine inhibition is sufficient to block PRMT5 activity in MTAP-deleted tumors in vivo. Nine of 12 MTAP deleted models evaluated at 80% to 100% reduction of tumor SDMA as compared to time matched vehicle controls. We will give you two vignettes from one of our key indications of interest on the next couple of slides. On slide 9, non-small cell lung cancer is a patient population of high interest for the IDE397 program and in this MTAP deleted lung squamous cell carcinoma PDX model, we achieve 92% tumor growth inhibition by in the study. With respect to the PD, the vehicle arm middle panel showed extensive SDMA standing with an H-score of 85. The tumor SDMA H-score was reduced to zero by IDE397 treatment, as shown on the right, indicating 100% suppression of the production of SDMA in the tumor. On slide 10. Here is another example in the same disease indication, where we saw a tumor regression by end of study. This tumor had an SDMA H-score of 250 and control animals quite high the max is 300, as you can see in the middle panel. 95% of that baseline signal is gone in residual IDE397 treated tumors, as you can see on the far right. On slide 11. As I mentioned earlier in the clinical Phase 1 dose escalation study, we're following plasma SAM as a peripheral PD biomarker and tissue SDMA as the tumor PD biomarker. We've observed significant plasma SAM reduction on treatment across Cohorts 1 through Cohort 5 to date. As an example, you can see the deep and consistent post treatment plasma SAM reduction among evaluable patients in our recently clear Cohort 5 on the left with a mean reduction of 77% after three weeks of therapy. On the right, you can see that across all evaluable patients on trial to date, the percent plasma SAM inhibition is associated with increasing drug exposure, indicating exposure dependent exposure-dependent modulation. On the next slide, we'll move to the tumor PD from the trial. So here on Slide 12, we were very pleased to see exposure associated tumor SDMA reduction in target tumor types. Our first pre-dose and on treatment paired biopsies came from a pancreas cancer patient from Cohort 4, shown on the far left and displayed little detectable modulation of tumor SDMA treatment. Cohort 4 pancreas cancer patient middle panel showed both nuclear and cytoplasmic SDMA staining in the pre-dose tumor biopsy. Those dark brown ovals are SDMA positive nuclei which are surrounded by lighter Brown cytoplasmic SDMA staining in the pretreatment biopsy shown in the top panel. This patient's AUC plasma drug exposure is about 2.5-fold higher than the pancreas cancer patient in Cohort 3. Notably, the cytoplasmic staining is absent on treatment with also a detectable, although modest reduction in nuclear SDMA staining, middle and bottom panel indicating an emerging pharmacological response to IDE397 in the tumor. Finally, on the right panel at the higher IDE397 exposures, you can see almost complete loss of SDMA staining in the post treatment biopsy from this lung cancer patient in Cohort 5. The plasma drug exposure in this patient is almost 6-fold higher than what we saw in Cohort 3 patient. We'll go in a deeper dive on the next slide. Slide 13 first, it's worth noting that the steady state exposures for patients in cohort 5 are getting within the predicted efficacious concentration range based on preclinical in vivo efficacy studies, using a representative MTAP deletion lung cancer model. This patient was on the high side of exposures observed in Cohort5 and the plasma SAM reduction is also on the high end at 79%. The central lab pathologist tumor SDMA score for the pre-dose biopsy was 280, as shown in the bar graph on the right, the vast majority of tumor cells in the pre-dose biopsy had the maximum SDMA standing intensity, receiving scores of 3 plus. In contrast, the [indiscernible] for the on treatment biopsy was only 13 and in the bar graph shown on the right, the vast majority of tumor cells in this sample were completely negative for SDMA receiving scores of zero. I'll sum up on the next slide. The slide 14 preclinically, we see strong tumor growth control as well as tumor regressions in multiple MTAP-deleted CDX and PDX tumor models using once daily oral IDE397 doses from 10 milligrams per kilogram and above significant reduction tumor SDMA is detectable at 3 milligrams per kilogram and is maximally suppressed by 30 milligrams per kilogram. We've plotted those exposure response details for the MTAP lung cancer model H838, on the right. Clinically, IDE397 achieved plasma SAM reduction of 60% or more across cohort 1 through 5 in the Phase 1. We've plotted the steady state exposures for the patients discussed in this presentation on the right, benchmarked against the preclinical observations. Clinical tumor SDMA is showing an exposure dependent relationship with 95% reduction of tumor SDMA in cohort 5. Based on these observations, cohort 5 is in the target exposure range for efficacy and we are currently exploring a higher dose in cohort 5. So with that I'll hand the presentation back to Yujiro.

[Yujiro Hata, Chief Executive Officer & President]

Great, Mike. Thank you so much for that walkthrough and thank you Matt for the walkthrough of the clinical data as well. In terms of key next milestones for IDE397, first is to deliver the GSK option package midyear 2022 and then second, to initiate both the monotherapy expansion and combination studies in mid-year 2022. And as noted earlier, the protocol amendment to the FDA has been submitted to enable this next phase of the clinical program. In terms of a summary of a presentation today, we believe we've demonstrated IDE397 shows robust suppression of tumor pharmacodynamics across multiple MTAP-deleted PDX models, including 100% reduction of tumor SDMA. We have completed the preclinical package for the option data package and the data has been uploaded to the option data package data room. Next, IDE397 has demonstrated a favorable human PK profile that we believe supports once daily dosing as noted on clinicaltrials.gov. IDE397 has demonstrated robust clinical plasma pharmacodynamics across all cohorts and exposure dependent tumor pharmacodynamics. Today, we've also observed a very favorable human AE profile, including no serious adverse events and the maximum tolerated dose has not yet been reached. Importantly, the summary of this data, we believe we are seeing an emerging pulmonary risk benefit profile versus historical. On the benefits side, as noted earlier, we have seen clinical activity including robust plasma and tumor pharmacodynamics and as reported earlier, tumor shrinkage in multiple patients. From a risk profile side, we believe we have observed a favorable AE profile including again no SAE's, an MTD that has not yet been achieved. To contextualize this risk benefit profile, we wanted to highlight two additional molecules in this pathway including GSK’s PRMT5 inhibitor, who had an expansion dose selected at 400 mg once a day, and as noted here that expansion dose you saw approximately 26% SAE’s and 53% Grade 3, 4 AEs. For 8270 at the 200 mg q.d. expansion dose, we observed just under 20% Grade 3 or higher AEs and at the next dose level up of 200 mg b.i.d., a 67% Grade 3 or higher AE. At the outset of this program, IDEAYA’s believe, it has been generating a molecule that has sufficient exposure that can deliver robust pharmacodynamic modulation with an AE profile that is superior from previous compounds would provide a unique profile to interrogate this opportunity within MTAP-deletion. We believe this interim clinical data positions the molecule well to enter into the next phase of development. We believe this favorable risk benefit profile will position IDE397 to potentially evaluate unique combinations as well as to explore potentially earlier lines of treatment as monotherapy agent. With that -- this is the conclusion of the prepared remarks. So, the IDE397 Phase 1 clinical program update. And with that, I will pass it along to Paul Stone, our Chief Financial Officer to provide an update across the portfolio as well as our financials as relates to our Q1 2022 earnings release update.

[Paul Stone, Chief Financial Officer]

Hi. Good morning, everyone. I'm Paul Stone, Chief Financial Officer of IDEAYA. I’m going to report on our financial results for the full-year 2021, as well as the corporate update. In 2021, for the full-year we had operating expenses of $78 million. This left us with a cash balance of $368 million, which provides us with a runway for plant operations into 2025. From a program perspective, our Darovasertib Phase 2 clinical and our pre-clinically programs are each maturing. Starting with Darovasertib, we are currently enrolling patients in a Phase 2 clinical evaluation of Darovasertib in combination with crizotinib in collaboration with Pfizer, and their clinical collaboration and supply arrangement. We are evaluating that combination in both metastatic uveal melanoma as well as GNAQ/11 mutant skin melanoma. We also opened recently a monotherapy evaluation of Darovasertib in primary uveal melanoma and we are considering and evaluating expansion opportunities pre-clinically both with KRAS inhibitors in KRAS driven tumors and in combination with crizotinib, potentially other cMET inhibitors in cMET-driven tumors. In terms of key updates in catalysts, we announced yesterday that we've expanded our relationship with Pfizer on our clinical collaboration and supply arrangement to support a potential registrational trial in metastatic uveal melanoma as well as part a Phase 1 clinical evaluation of the combination in cMET-driven tumors subjected to pre-clinical validation. Finally, for this program, we are targeting FDA guidance, as well as the clinical data update in mid-year 2022. Our next most advanced program is IDE161, which is a wholly-owned program targeting PARG for patients that have HRD or BRCA mutations. In this program, we've observed in vivo efficacy with enhanced tumor growth inhibition and/or tumor aggressions in multiple niraparib resistant models, which is a PARP inhibitor. We're targeting an IND in Q4 of this year. In our Pol Theta, also partner with GSK, we’ve demonstrated in vivo efficacy in combination with niraparib, which is GSKs PARP inhibitor, and we are in IND enabled settings first half of this year. Importantly for this program with GSK, we have the potential for up to 20 million in aggregate, additional milestones from pre-clinical to early Phase 1 Finally on Werner Helicase, we are targeting a development candidate with GSK in collaboration with them in 2023. And similarly for this program, we have the potential for up to 20 million aggregate milestone payments from pre-clinical to early Phase 1. We're excited to see these programs mature.

[Yujiro Hata, Chief Executive Officer & President]

Great. And Paul, anything additional for the financial results or is that the conclusion?

[Paul Stone, Chief Financial Officer]

I think that – I think we covered the financial results, as I said $78 million of operating expenses for 2021 cash into 2025 with $360 million on the balance sheet for this year.

[Yujiro Hata, Chief Executive Officer & President]

Okay, great. Thank you, Paul, for that summary. And this is will be the end of our prepared remarks and with that the operator will open up for the analysts Q&A session.

[Operator]

[Operator Instructions] We will take our first question from Anupam Rama with JPMorgan. Please go ahead.

[Anupam Rama, JPMorgan]

Hey, guys. Thanks so much for taking the question. Just a logistical question for me, can you remind us when sort of the data upload is complete to GSK by midyear? How long GSK has to make a formal opt-in decision? And will you be disclosing when the package is delivered or just ultimately the GSK decision? Thanks so much.

[Yujiro Hata, Chief Executive Officer & President]

Yeah. Yeah, Anupam, so the timeframe for GSK's review period has not been disclosed. But I would say that, we've been in very close communication with GSK towards the end of last year. Based on that communication, we've begun building the data room early. And a lot of the data room has already been occupied, including preclinical data, as well as several key pieces of the clinical data. So our view is that one the doses selected for the expansion phase of this trial. It will be an incremental review, which we would hope, would enable an efficient, time efficient decision by GSK on the opt-in. In terms of, would we provide guidance and when the option package is delivered? Relative to the decision by GSK, we have not made on the -- made a decision on that on upon at this point. But I think our hope is that those two events may be in fairly close proximity. And based on that, I think it may not be a bad baseline assumption that we would make an announcement as part of an actual GSK decision on the option.

[Anupam Rama, JPMorgan]

Thanks so much for taking my question.

[Yujiro Hata, Chief Executive Officer & President]

Sure.

[Operator]

And our next question comes from Maury Raycroft with Jefferies. Please go ahead.

[Maury Raycroft, Jefferies]

Hi. Good morning. And thanks for taking my questions as well. I was just wondering if you can talk more about what exactly is going to be submitted to GSK. It sounds like it's subject to initiation of expansion Cohort s or MTD? And you're starting dosing with dose Level 6. And so just wanted to see we can talk more about what else could still impact or be included in the GSK data package. And will you include any data from Cohort 6 in the package?

[Yujiro Hata, Chief Executive Officer & President]

Yeah, so I think in terms of data categories that will be provided in the option package that's noted in the schedule and our agreement was as outlined in one of the earlier slides of the presentation. In terms of Cohort, Maury here, I would say it depends on how Cohort 6 owes. So we are currently in that Cohort, as I believe as noted in the print materials. We have clear the first patient on the DLT [ph] window. My understanding is that second patient will likely clear sometime next week, if they get through next week. And so it depends on if six is a possible dose for its reaction. If it's up to five than we end up selecting five in expansion dose, I would say the data that what was presented today will be will be largely the day they save. If it's a scenario that we decide to escalate into Cohort 7 and we clear that Cohort -- obviously that Cohort will be included as well. I would say at this point, the baseline working assumption that we are internally utilizing for planning for this next phase of development is that the potential to expand that this current cohort we're rolling which is Cohort 6.

[Maury Raycroft, Jefferies]

Got it. That’s very helpful. And also just wanted to check to see if you're seeing anything additional on impact on bilirubin and you've mentioned the UGT1A1 biomarker in the past, I'm just wondering if you can remind me if you've assessed that in the clinic, and if you're seeing any differences versus AG-270 on those measures?

[Yujiro Hata, Chief Executive Officer & President]

Sure. Matt, do you want to answer that in terms of liver safety profile today versus AG-270 and our clinical experience there?

[Matt Maurer, Head, Clinical Oncology]

Yes, so we don't have the liability on the liver enzyme. So, -- and we have not seen any significant liver toxicity today. So, we're encouraged by that.

[Maury Raycroft, Jefferies]

Got it. Okay, thanks. for taking my questions.

[Yujiro Hata, Chief Executive Officer & President]

Great. Thanks Maury you.

[Operator]

And we'll take our next question from Charles Zhu with Guggenheim Securities.

[Charles Zhu, Guggenheim Securities]

Good morning everyone. Thanks for hosting this event and thanks for taking my questions. My first one I want to ask on the tumor SDMA downmodulation signals that you've disclosed so far. I guess in addition to potentially looking at it from the perspective of percent tumor SDMA reduction, how should we also think about these tumor SDMA levels? Not only as a percent reduction, but also on an absolute level of for example, the Cohort 4 pancreatic cancer patients who have showed some level of knockdown, but post-treatment, it looks like the absolute amount could still be perhaps comparable to what some other tumors may be on the pretreatment perspective. So, I guess could you provide thoughts on that front as well, not only on the percent knockdown, but also on absolute amounts post-treatment? Thanks.

[Yujiro Hata, Chief Executive Officer & President]

Mike, do you want to take that?

[Michael White, Chief Scientific Officer]

Yes, absolutely. Thank you for that question. With respect to the absolute SDMA signal, when we look at that signal, we are really looking at the proteins that have been modified by that symmetric dimethyl arginine and our therapeutic mechanism of action requires that demethylation to occur in order to support the pre-mRNA splicing that will allow the tumor to thrive. So, in terms of absolute concentrations of SDMA in the tumor, preclinically, we find that the better you suppress those absolute values of SDMA, the better response you have with respect to tumor shrinkage. So, in terms of what the absolute values are in the clinical arena, and whether or not there's going to be indications-specific thresholds for efficacy remains to be seen, but from the preclinical studies we do know that the more we can suppress tumor SDMA the better efficacy we see in those preclinical models, both the CDX and the PDX.

[Charles Zhu, Guggenheim Securities]

Got it understood and I guess -- I'm also curious, then what are the potential implications on pre-treatment H score impact and would we -- could we still potentially expect to see efficacy in low baseline H score to tumors?

[Michael White, Chief Scientific Officer]

Do you want me to take that Yujiro?

[Yujiro Hata, Chief Executive Officer & President]

Sure. Yes.

[Michael White, Chief Scientific Officer]

From what we have seen on the preclinical side, when we have a response to the MAT2A inhibitor, we have a suppression of the tumor SDMA. We have found tumors that have H-scores of 80 to a 100 that grow well and become suppressed and we have tumor control with SDMA with the MAT2A inhibitor treatment I showed you an example of that with one of those lung cancer, squamous cell lung cancer samples. We also have tumors that have H-score of close to 300, which is the maximum H-score that you can have and we find that we can suppress that all the way down to single or low double digits and that corresponds to efficacy. So the absolute concentration of SDMA in any given sample, we think is going to be variable. It's going to be based on the snapshot in time with respect to the turnover rate of the proteins that are methylated, as well as, the activity of the enzymes involved is going to be related to the speed of the growth of the tumor. But we do find that we see efficacy, irrespective of the starting point of the SDMA signal as long as we are able to suppress that with sufficient exposure to IDE397.

[Charles Zhu, Guggenheim Securities]

Got it. Thanks for providing that level of color and detail and maybe just one last one, I’d like a squeeze it in. I may have missed it but what's the potential significance of observing what appears to be 100% knockdown of cytoplasmic SDMA while also knocking down 12% of the new nuclear SDMA in that cohort for patients next.

[Yujiro Hata, Chief Executive Officer & President]

Matt you wanted to add again.

[Matt Maurer, Head, Clinical Oncology]

Sure, I'll take that one too. What we're seeing in that patient, is signs of activity of IDE397 in the tumor that is indicated by a reduction in the signal of the cytosol. And a little bit in the nucleus. We don't understand the mechanistic relationship there, with respect to whether a tumor has a cytosolic signal or not. So what we can say at this point is, in that cohort for patient, we are seeing emerging signs of productive pharmacology vis-à-vis. The drug is getting to the site of action for the intended therapeutic mechanism, is engaging the target and is having a consequence on the pharmacology. That's the extent of the conclusion that we wish to draw.

[Charles Zhu, Guggenheim Securities]

Got it. Thanks for taking all my questions.

[Yujiro Hata, Chief Executive Officer & President]

Great. Thanks for the question, Charles.

[Operator]

And our next question comes from Joel Beatty with RW Baird. Please go ahead.

[Joel Beatty, RW Baird]

Hi, thanks for the presentation. First question is for the size SAEs and the Grade 3 AE, can you share what doses they occurred at?

[Yujiro Hata, Chief Executive Officer & President]

Sure, Matt, do you want to take that?

[Matt Maurer, Head, Clinical Oncology]

Yes, so the OCAR [ph] SAEs occurred across doses and are generally related to complications of their malignancies and progression of their malignancies.

[Joel Beatty, RW Baird]

And I think the one was also the one Grade 3

[Matt Maurer, Head, Clinical Oncology]

I see the Grade 3 Avastin -- Avastin at -- dose level four

[Joel Beatty, RW Baird]

Got it. I appreciate that. And then also, could you confirm whether GSK will take response data and progression data at all into consideration when they make their opt-in decision?

[Yujiro Hata, Chief Executive Officer & President]

Yes, I think at this point Joel, the schedule of the option data package requirement is the data that we've provided around the categories including pharmacodynamic data. So at this point, those are the contents of the actual option data package. Obviously, the two organizations are in regular communication through the both the joint development committee of MAT2A as well as the joint steering committee. But just to be clear that the actual schedule for the option decision, the data requirements ends with the pharmacodynamic -- tumor pharmacodynamic data.

[Joel Beatty, RW Baird]

Great. Thank you.

[Yujiro Hata, Chief Executive Officer & President]

Sure.

[Operator]

[Operator Instructions] Our next question comes from Ben Burnett with Stifel. Please go ahead.

[Ben Burnett, Stifel]

Hi. Thank you very much for taking our question. I guess based on what you're seeing thus far, what's your current expectation for how long SDMA and how long SAM levels need to be reduced before seeing a clinical response?

[Yujiro Hata, Chief Executive Officer & President]

Yes. Great question, Joel. Mike, do you want to take a stab at that one?

[Michael White, Chief Scientific Officer]

I can. One of the things that is an important mechanism of action for us is perturbation of splicing, which then has a consequence on the protein milieu within the tumor that is supporting the disease state. So our mechanism of action requires inhibiting the enzyme that modulates the splicing factors that causes the splicing perturbation that interferes with protein function. So it's a multi step process and we'll create a situation where some time is required in order to be able to have sufficient suppression of tumor selected proteins that are supporting tumorigenesis. When we look at the pre-clinical models, sometimes we see situations where upon dosing the tumor continues to grow and then turns over and is controlled. In other models, we see control from the beginning. So there may be indication specific differences in the timing. There may be an indication significant -- indication specific rather differences with respect to how fast we see a consequence of these effects based on the turnover rate of the splicing factors that are methylated. So there are a lot of factors at play here that could affect the timing at which the therapeutic mechanism is engaged. From our preclinical studies what we do know is that we need to stay on the target in order to be able to maintain control of the tumor. And we need to be able to suppress the target strongly to be able to evoke a productive pharmacological response continuously over time.

[Yujiro Hata, Chief Executive Officer & President]

And maybe just, Ben, I just would add to Mike’s -- I think, related in addition to duration to your question, as Mike noted, I think, here at the importance of continuous dosing without having dose holidays, dose reductions, and that's why we did the comparative at the end of the presentation versus some of the historical, because as we've seen some of that pharmacodynamic data, but based on the AE profiles, obviously, I think, the continuous dosing, lack of dose holidays and dose reductions, obviously have been challenging for some of these past molecules.

[Ben Burnett, Stifel]

Understood. Okay. That's super helpful. And just one quick kind of clarification question. You mentioned some higher dose cohorts is the -- is there a goal or is there an appetite to go up until you hit an MTD, or you plan on stopping at a certain dose Cohort?

[Yujiro Hata, Chief Executive Officer & President]

Yes. That's a great question, Ben. I think we are having that discussion internally. And we'll be continuing the communication with GSK. We do think now in Cohort 6 based on the PK/PD data that Mike, and the human PK data that Matt walk through. We do think we're at that dose range where we believe we're in the efficacious range. So I think there is a very likely scenario that if we clear this Cohort 6, that we would initiate the monotherapy expansion at that dose, and then for example, start the combination at dose minus one. And while we do that, we could in parallel, continue the dose escalation to Cohort 7. So -- but I think these are all discussions that are occurring real-time, but I think that's a potential scenario.

[Ben Burnett, Stifel]

Okay, okay, that makes sense. Thanks very much.

[Yujiro Hata, Chief Executive Officer & President]

Sure. Thanks for the question Ben.

[Operator]

And the next question comes from Tim Chiang with Northland Securities. Please go ahead.

[Tim Chiang, Northland Securities]

Hi, thanks. Yujiro, just going back to the GSK opt-in decision, is there any requirement for them -- for actually for you to show a maximum tolerated dose before they opt-in? I'm just wondering, do you have enough data to show to GSK such that GSK would opt-in, what do you think the likelihood of that is, at this point?

[Yujiro Hata, Chief Executive Officer & President]

Yeah. So Tim, the way the schedules written for the option, it's the expansion dose selected for this next phase of development or MTD. So -- and so it really it's based on the decision we make for initiating the monotherapy expansion. I think separately to the question that Ben asked earlier, I think there is a scenario that we would pick a dose, for example, Cohort 6 as the expansion does as we continue to does escalate to define MTD. But that's not a requirement for the option package delivery. It's really more based on the dose selection for the next phase and that could be either a lower dose or an MTD dose.

[Tim Chiang, Northland Securities]

I see. Okay. And maybe just one follow-up and it's really on darovasertib. I mean, I guess you just announced the expansion of that collaboration with Pfizer. Could you just talk a little bit about what that entails? Is Pfizer going to supply you more product -- more active product, or are they also going to devote some resources to this studies going forward?

[Yujiro Hata, Chief Executive Officer & President]

Yeah, we're very excited to be able to make that announcement yesterday on darovasertib with Pfizer, and there were two agreements or two new agreements that were put into place. And so first for metastatic uveal melanoma, in our earlier agreement with Pfizer, it was a very specific that it would not include work for a registrational trial. So the new agreement that was put in place was specifically to enable a potential registration enabling trial. And I think part of that is because it does require more just engagement interaction with Pfizer, both from a regulatory perspective, and Tim as you can appreciate, if approved, obviously, would be a label changing of that as well. In terms of the setup, for that it is similar in terms of supply. There is a joint steering committee. The two organizations do meet fairly regularly. In addition, obviously, their involvement both in terms of certain specific regulatory documents and communication with the FDA. Obviously, the development of the clinical protocol. There are also specific provisions around joint intellectual property of which joint IP has been filed here already as well as joint publication rights. The second agreement is separate and that is to explore this combination of darovasertib with crizotinib and additional cMET driven tumors, including as was noted hepatocellular carcinoma. And we believe another indication non-small cell lung cancer which it appears Pfizer has interest to explore this combination. So that as well, the design, the protocol, in conjunction with Pfizer has been developed. And in parallel, we are also doing some preclinical validation work as was noted in our earnings update today. And that setup is basically mirrors what I noted for the registration MUM as well except that it's not for registration and supply that would be a next step pending this initial signal seeking study.

[Tim Chiang, Northland Securities]

Okay. Yeah, that's good details. Thanks, Yujiro.

[Yujiro Hata, Chief Executive Officer & President]

Yeah. Absolutely, Tim. Thanks for the question.

[Operator]

And we will take her last question in queue today coming from Zegbeh Jallah with Roth Capital Partners. Please go ahead.

[Zegbeh Jallah, Roth Capital Partners]

Good morning. Thanks for the update. I think I just have two quick ones. The first one is a follow-up to the question that was asked earlier by SDMA and the absolute versus percentage change. And so, I just kind of want to get into, how strong the correlation is between that and tumor reduction and based on the data that you have so far? And then, I guess another thing I wanted to ask was, perhaps some variability that you may be seeing what might be driving us, is it the tumor type, what are some of the variabilities that you're seeing, and how do you plan to tackle that?

[Yujiro Hata, Chief Executive Officer & President]

Yeah. So I think first on the just I would say clinical side, we've already shown earlier is, is that as you know, CT scans of tumor shrinkage and I believe several of those patients and I was -- we commented on a thymic patient, I believe was on study at that point of the disclosure about six months earlier in the Cohort, this escalation and we did not have tumor biopsies for those patient. So I would say we're somewhat dealing with the limited and number in terms of the at least currently on the Phase 1 dose escalation on that specific question. But I think we have a lot of data preclinically on that association between SDMA reduction and tumor growth inhibition regression preclinically, but Mike, any additional comments there you want to make?

[Michael White, Chief Scientific Officer]

Yeah. Thanks, Yujiro. Thanks for the question. Yeah, that was great. Just as a little bit of a follow-up from a preclinical standpoint, Zegbeh what we're really looking at here is not the delta so much as getting below a threshold. So everything that we've seen so far suggests that you need to get below a threshold of SDMA to have response. You're not always necessarily going to get a response there is in some models required, but not sufficient in the preclinical setting, but we're looking at a situation where we want to get below a threshold of SDMA in the tumor to be able to have efficacy.

[Zegbeh Jallah, Roth Capital Partners]

In terms of the variability, I guess, in patients getting below that threshold, versus those that are not, are you seeing anything there in terms of nuances and baseline characteristics?

[Yujiro Hata, Chief Executive Officer & President]

Yeah, I would say Zegbeh, in terms of our clinical data, I think the -- at this point, the Pharmacodynamic data that we have on every patient is plasma and there it's a fairly consistent and robust reduction of the Pharmacodynamic marker. In terms of tumor PD, it's in a smaller subset of patients. So I think, it's a bit hard to say in the -- at least at this point, right now, we did show pancreatic, as well as lung cancer at least in the figures today. So, I think we just need a larger data set to comment on that specific question, clinically at this point.

[Zegbeh Jallah, Roth Capital Partners]

Thanks, Yujiro. And then the math, I know that the combo data is not required for the package that will be submitted to GSK. But I was just wondering, in terms of when GSK has to make the decision, relative to when you will have the combo data, is it likely that you will have the combo data before GSK has to make their opt-in decisions, just kind of wondering, about how the combo data might help influence some of that decision making?

[Yujiro Hata, Chief Executive Officer & President]

Yeah. In terms of combination data, Zegbeh, there is no requirement for us to have clinical combination data. We have been working very much in a highly collaborative fashion. GSK from our perspective has added a tremendous amount of value on the preclinical combination of valuation, both in terms of GSK running agnostic screen, as well as helping IDEAYA think through really the scientific rationale and basis for a lot of these combinations. And I think there, we are in very solid footing at least from our perspective, and we do have three combination arms that have been submitted as part of this protocol amendment with the FDA. But just to be clear, that is not the clinical portion, at least it's not required as part of the option package.

[Zegbeh Jallah, Roth Capital Partners]

Thanks, Yujiro.

[Yujiro Hata, Chief Executive Officer & President]

Great. Thanks so much, Zegbeh for questions. Operator, are there any more questions on queue?

[Operator]

No, there are no further questions.

[Yujiro Hata, Chief Executive Officer & President]

Great. So with that, we'll conclude the IDE397 Phase 1 update, as well as Q1 22 earnings update and again, thank you very much for the time and operator, thank you so much for hosting the Q&A session.

[Operator]

This concludes today's call. Thank you for your participation. You may now disconnect.