Good day, and welcome to the Regulus Therapeutics Special Update Call. All participants will be in listen-only mode. Should you need assistance, please signal a conference specialist by pressing the star key followed by zero. After today's presentation, there will be an opportunity to ask questions. To ask a question, you may press Star, then one on a touch-tone phone. To withdraw your question, please press Star, then two. Please note, this event is being recorded. I would now like to turn the conference over to Cris Calsada, Chief Financial Officer. Please go ahead. Thanks, operator. Good morning, and thank you for joining us for this special update on top-line results from the third cohort of our phase I-B multiple ascending-dose clinical trial of RGLS8429 for the treatment of autosomal dominant polycystic kidney disease. Before we begin, I'd like to remind you that this call will contain forward-looking statements concerning Regulus future expectations, plans, prospects, corporate strategy, and performance, which constitute forward-looking statements for the purposes of the Safe Harbor provisions under the Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including those discussed in our filings with the SEC. In addition, any forward-looking statements represent our views only as of the date of this webcast and should not be relied upon in representing our views as of any subsequent date. We specifically disclaim any obligations to update such statements. Joining me on today's call is Jay Hagan, Chief Executive Officer, and Dr. Preston Klassen, President and Head of R&D. I will now turn the call over to Jay. Jay? Thanks, Cris, and good morning, everyone. We're excited to share the top-line results from cohort 3, our final placebo-controlled, weight-based dosing cohort of our ongoing phase I-B study of RGLS8429 in patients with ADPKD. My colleague, Dr. Preston Klassen, will walk through the program update in detail shortly. Before we get to that, though, I want to again thank the patients and physicians working with us on our investigational product designed to address the underlying genetic drivers of the disease. Based on the results that Preston will walk through, we are very encouraged with the results from cohort 3, given their consistency with what we reported earlier this year from cohort 2. After Preston's review of the program and data from the ongoing phase I-B, I will conclude with a summary of our next steps based on these encouraging results. I want to again emphasize that this is a disease with significant unmet medical need for patients and caregivers, and one where a new therapeutic option would likely represent an important step forward. Preston? Thanks, Jay. First, I want to cover the summary findings from cohort 3 so everyone has that in mind, and then I'll step back a bit with some background on the disease, ADPKD, and the mechanism of action for the oligonucleotide RGLS8429, and then we'll dive into the cohort 3 data. With any new cohort in multiple ascending dose trial, safety is a top priority. 3 mg/ kg of RGLS8429 dosed every two weeks over 12 weeks was generally well-tolerated with no safety concerns noted, and we'll show the summary data for that. The next objective is to demonstrate mechanistic activity using our pharmacodynamic biomarker, urinary polycystin, measured in urinary exosomes. At 3 mg/ kg, we continue to see clear evidence of a mechanistic dose response compared to our earlier cohorts at 1 mg/ kg and 2 mg/ kg. In particular, at 3 mg/ kg, we see more consistent increases in polycystin across patients, and percent change from baseline in both PC1 and PC2 demonstrate a dose response over the course of the trial across all doses, with statistical significance seen at 3 mg/kg compared to placebo. We are also very encouraged by exploratory imaging analyses of kidney volume that continues to suggest an impact of RGLS8429 on total kidney volume after only three months of dosing. In particular, 70% of patients receiving 3 mg/kg demonstrated reductions in height-adjusted total kidney volume, most of which were reductions from baseline of between 2.5% to 6%, which is notable and encouraging. Additional exploratory analyses suggest that the 2 mg/kg and 3 mg/kg dose levels, we see increases in polycystin-1 and polycystin-2 that are directionally associated with reductions in total kidney volume and increases in kidney function as measured by eGFR. So overall, the results we will walk through clearly meet our expectations for the key objectives in this phase I-B trial, and we think exceed expectations in terms of continuing to suggest an impact on kidney volume after short-term dosing. But first, I'm going to step back and provide a brief overview of autosomal dominant polycystic kidney disease or ADPKD, its pathogenesis, and the mechanism of action of RGLS8429. ADPKD is one of the most common monogenic diseases, and it is also the most common hereditary kidney disease. There are two forms of ADPKD, caused by germline defects in either the PKD1 gene or the PKD2 gene. Now, PKD1 represents 80%-85% of the disease. It is the more severe of the two, with an average onset of complete kidney failure by 55 years of age. It is an orphan disease with approximately 160,000 prevalent patients in the U.S., and it accounts for approximately 5% of the total end-stage renal disease patient population. And while direct costs for renal replacement therapy in these patients are around $4 billion annually, the total yearly cost of all ADPKD care is estimated to be $8 billion-$9 billion. Existing therapy is limited to one approved drug, tolvaptan, a vasopressin receptor antagonist that also decreases cyclic AMP levels and has been shown to slow the cystic growth of the kidney by 50%, which is associated with a slowing of the rate of decline in renal function by approximately 30%, again, as measured by eGFR. Tolvaptan therapy is limited by significant tolerability concerns related to free water excretion, causing significant polyuria and thirst, and there are safety concerns with a black box warning for potential fatal liver toxicity. Despite these limitations, annual sales of tolvaptan approach $1.3 billion, up over 30% from last year's sales figures. So all of this contributes to a very viable and attractive landscape for developing a novel therapy in this space. The unmet need for an effective therapy that is also well-tolerated and safe is clear. Orphan status of the disease affords a more streamlined regulatory path, and cost-effectiveness related to a delay in the time to end-stage renal disease may be more evident due to the high cost of renal replacement therapy. ADPKD exhibits autosomal dominant inheritance, meaning it only takes one copy of a mutated gene passed down from one parent to inherit the disease. The germline mutation in the PKD1 or PKD2 gene triggers an abnormal proliferation of renal tubular epithelial cells and the transformation of those cells into cystic epithelial cells with the formation of numerous fluid-filled cysts throughout the kidney, causing significant growth and enlargement of the kidney itself, which disrupts and eventually destroys normal kidney tissue. While the genetic mutation is present from birth, genetic screening is not routine, and clinical manifestations generally occur later in life, with the diagnosis often made after investigation for flank pain due to enlarged kidneys, or a notable decline in GFR by labs, which may not occur until the fourth or fifth decade of life. At times, diagnosis is made by an incidental finding of an enlarged kidney on ultrasound or other imaging procedures. As you can see on the far right, polycystic kidneys can grow to an extreme size, necessitating surgical removal. This is a very serious disease that results in the insidious loss of renal function with eventual complete kidney failure, and the intended morbidity and mortality associated with end-stage kidney disease cannot be overstated. Any therapy that can slow the progression of polycystic kidney disease, slow the time to dialysis, is needed and highly sought out by the physicians who treat this disease and the patients who suffer from it. Now, before I discuss the molecular pathogenesis of disease and the mechanism of action for 8429, it's important to mention microRNA, because that's the therapeutic target of 8429. MicroRNAs are short, non-coding RNA segments that bind to complementary sequences located in the 3-prime untranslated region of the target messenger RNA. When a microRNA binds to its target messenger RNA, it results in translational repression. The protein encoded by that mRNA is not synthesized, which reduces that protein level, and eventually, the targeted mRNA transcript itself is degraded. An abnormal upregulation that increases cohort has been shown to promote the progression of many human diseases, which presents an opportunity to selectively inhibit pathogenic levels of microRNA by using an oligonucleotide that has complementary binding to the specific seed region of the target microRNA. In this way, the oligonucleotide is acting as a competitive inhibitor, stopping the target microRNA from binding to messenger RNA. Now we're going to take a look at the pathogenesis of PKD and the role that a specific microRNA family plays in disease progression, and we'll start on the left-hand side of this slide. The genetic mutation in PKD1 or PKD2, through a variety of transcription factor signaling pathways, drives overexpression of the oncogene c-Myc, which is shown here, and also c-Fos and c-Jun. In the kidney, these pathways trigger overexpression of a specific microRNA family, miR-17. Indeed, miR-17 has been shown to be upregulated in both animal models of the disease as well as in patients with ADPKD, and we'll show that on the next slide. Increased miR-17 binds to and represses a variety of messenger RNA targets and causes dysregulation of multiple gene networks, reducing the expression of some genes and actually increasing the expression of others. This is important because recently, PKD has been recognized to be much more than a single gene mutation involving a single protein. The disease is caused by a single gene mutation that actually creates widespread gene network dysregulation. As we and others have demonstrated, the gene networks that are most impacted by miR-17 upregulation tend to themselves regulate proliferation. We see that genes that are involved in limiting proliferation are inhibited when miR-17 is increased. An important example of this is the PKD gene itself, because its messenger RNA encodes the protein polycystin, and polycystin's natural job is to maintain normal renal tubular epithelial cell structure and function and control cell proliferation. miR-17 binds the PKD1 and PKD2 messenger RNA and blocks the production of polycystin. In addition to reducing the production of polycystin, the increase in miR-17 that occurs in disease affects many other gene networks. It reduces PPAR-alpha, PPAR-gamma, PPAR-gamma cofactor-1 alpha, among others, which are also anti-proliferative genes working through oxidative phosphorylation in the mitochondria. And an excess of miR-17 actually increases other gene networks, and the genes that are increased either promote abnormal cell proliferation like RICTOR and mTOR, or promote inflammation and fibrosis via immune mediators, and we will show evidence of this in a moment. So one important way of looking at miR-17 is as a gatekeeper or important control point in the dysregulation of renal tubular cell biology that ultimately results in abnormal proliferation and cell transformation from normal renal tubular epithelial cells to cystic epithelial cells, driving cystogenesis and then growth of kidney cysts with eventual destruction of normal renal function. And now on the right-hand side of the slide, we see where our antisense oligonucleotide, RGL8429, fits in. RGLS8429 is designed to preferentially distribute to the kidney and bind with high specificity to the microRNA miR-17. By using RGLS8429 to competitively bind to and inhibit miR-17, evidence shows that you can stop the repression of messenger RNA across multiple gene networks, which rebalances them. Gene networks that were inhibited by miR-17 are now increased back toward normal. Gene networks that were increased by miR-17 are now reduced back towards normal. In animal models, blockaded miR-17 with RGLS8429 has been shown to attenuate cystogenesis and abnormal growth of the kidney, and this involves an increase in the production of polycystin. So we measure polycystin in patients as a key marker of mechanistic activity using a urinary exosome assay. By blocking miR-17, we should see an increase in the production of both polycystin-1 and polycystin-2, and eventually the excretion of those proteins via urinary exosomes. I'll cover 2 preclinical slides that nicely demonstrate the importance of miR-17 in the pathogenesis of disease and also in the opportunity for therapeutic intervention. First, we know that miR-17 is upregulated in PKD. Starting on the far left of the slide, in mice with a complete knockout of either the PKD1 or PKD2 genes, you see overexpression of miR-17 via quantitative PCR analysis. In the middle panel, kidney tissue from human patients with disease also demonstrates clear upregulation of miR-17 and, of course, the presence of renal cysts. Now, the far right panel is very interesting. Here we have mice that do not carry the PKD mutation. Instead, they only have transgenic overexpression of miR-17. And in the right side of that panel, look at what happens when a normal mouse just makes more miR-17. You see hyperproliferation of renal tubular cells and the development of renal cysts. The mice begin to develop a PKD phenotype just by virtue of an increase in miR-17. Another bit of evidence that supports the importance of miR-17, both in disease pathogenesis and as a therapeutic target, is to look at what happens to specific gene expression in disease and then see how that expression is altered when you block miR-17 with RGLS8429. The left panel shows a full transcriptomic analysis. We used RNA-Seq analyses to identify over 13,000 genes in the kidney of three groups of mice: normal mice, PKD mutation disease mice, and PKD disease mice that were then treated with RGLS8429. We performed comparative differential gene analysis to quantitatively compare gene expression between these different animal groups, and each dot in the figure on the left represents how gene expression changes across two specific animal group comparisons. So gene expression changes in a PKD disease animal compared to a normal animal is plotted either north or south of the X-axis. If the PKD disease increases the gene expression, it's plotted north of the X-axis. If the PKD disease decreases gene expression, it's plotted south of the X-axis. And the change in gene expression in a diseased animal that is treated with 8429 compared to an untreated diseased animal, is plotted to the left and the right of the Y-axis. If treatment reduces gene expression, it's plotted to the left of the Y-axis. If treatment increases gene expression, it's plotted to the right of the Y-axis. Now, the green dots that you see are the genes that are significantly impacted, both by disease alone compared to no disease, and also significantly impacted by treatment with 8429 compared to no treatment. Using this technique, we can understand quantitatively how much the expression of a gene changes just because of the PKD mutation that causes disease, and then for that same gene, how much the expression changes when RGLS8429 treatment is introduced. If RGLS8429 treatment were able to completely reverse the changes in gene expression that are caused by disease, the slope of the green dots would be -1, and that is very close to what we're seeing in this transcriptomic analysis. Now, the right panel on this slide dives in to take a closer look at specific gene networks that are impacted by both disease and RGLS8429 treatment. Using the Gene Set Enrichment Analysis, or GSEA, we identified a number of gene networks associated with known biological pathways that were highly impacted, both by disease and treatment. These biological pathways or gene networks are listed on the left side, and the first column on the left quantifies the expression of a predefined set of genes for each of the gene networks in mice with the PKD mutation compared to normal mice. So red indicates an enrichment or an increase in activity of those gene sets, and blue indicates a reduction. The first six gene sets listed are gene networks involved in promoting proliferation, MYC targets, β-catenin, mTOR, and others. These are enriched in PKD mice compared to normal mice. The next five are networks involved in inflammatory signaling and inflammatory mediators, TNF-alpha, IL-6, interferon gamma, and others. These are also enriched. At the bottom are genes involved in controlling oxidative phosphorylation in mitochondria. These include PPAR-alpha, PPAR-gamma, and others. The function of these genes tends to reduce or limit proliferation. In the setting of the PKD mutation, the activity expression of these genes is low. So the overall profile of these gene networks that occurs when the PKD gene mutation is introduced is a profile that favors cellular proliferation, cystogenesis, and inflammation. The columns to the right compare the expression of those same biological pathways or sets of genes in mice with a PKD mutation who are also treated with RGLS8429, versus mice with a PKD mutation who are not treated. You can see in a dose-dependent fashion, right to left, anti-miR-17 treatment with 8429 reverses the gene expression changes induced by the PKD mutation. Gene expression that is enriched by disease, shown in red, is reduced with 8429 therapy, now turned blue. Gene expression that is reduced in disease, shown by the blue, is enriched with RGLS8429 therapy, now turned red. So what these last two slides tell us is that miR-17 plays an important role in the development and progression of polycystic kidney disease, and that a mechanism of action that blocks the ability of miR-17 to impact gene expression can potentially be a very powerful tool to modify disease progression. That's the background on the disease and the mechanism of action for RGLS8429, and this slide lays out where we sit today in terms of the overall clinical development plan. We are currently executing the phase I-B multiple ascending-dose trial, reporting out today the data from the third dosing cohort. Now, this is primarily a proof-of-mechanism study, evaluating the impact of RGLS8429 on a biomarker that reflects mechanistic activity, urinary polycystin. We are also conducting exploratory measurement of kidney volume using MRI. Now, the next study is a phase II proof-of-clinical-concept trial, where the primary focus is treatment impact of 8429 on kidney volume as measured by MRI. The primary endpoint will be height-adjusted total kidney volume or htTKV. Importantly, because ADPKD is a clinical indication that is appropriate for accelerated approval using total kidney volume as the accepted surrogate endpoint, this next phase II trial can actually support accelerated approval as a single pivotal study, and we've confirmed this in a meeting with FDA last year. Our next study, if successful, will serve as the basis for accelerated approval and subsequent commercialization. As a post-marketing requirement, during commercialization, we will need to complete a confirmatory phase III trial to confirm clinical benefit, measured as improvement in estimated GFR or eGFR, compared to placebo. So that's the background on the disease, the mechanism of action for RGLS8429, and an overview of the clinical development program. So let's get into the current phase I-B study. We'll look at study design, the baseline characteristics, safety, and pharmacokinetics. This is an ongoing phase I-B study. It's a multiple ascending-dose trial examining three weight-based cohorts, testing RGLS8429 at 1, 2, and 3 mg/ kg in patients with ADPKD compared to placebo. And the final fourth cohort investigates a 300 mg fixed dose of RGLS8429 in an open label setting. The first three weight-based cohorts enroll 12 to 16 patients in a 3:1 randomization, active and placebo. Each cohort is dosed for 12 weeks. RGLS-429 is delivered as a subcutaneous injection every other week, so there are seven doses in each cohort. The inclusion criteria are a diagnosis of ADPKD with a screening MRI to classify patients according to the Mayo Imaging Classification formula, and we require patients to be Mayo Imaging Class 1C, 1D, or 1E. This corresponds to moderate to severe disease. Additionally, eGFR must be between 30 and 90 mL/min. Primary objectives are safety and tolerability as we increase the dose, along with evidence of increased mechanistic activity, which, as I mentioned, is evaluated by measuring polycystin within urinary exosomes. Polycystin is measured 3x over the baseline period and then monthly during the three-month treatment period. Then we continue to monitor polycystin for one month after dosing, and our end-of-study value is taken as the average of the last five measurements, specifically before and after dose seven, and then 3x over the following month. The end-of-study polycystin value is the average of the levels on days 85, 86, 92, 99, and 113. In part, this is due to the fact that we are working to understand the temporal kinetics of polycystin excretion in the urine. We reach steady state exposure of RGLS8429 after the fifth dose on day 57, as the oligonucleotide has a two-week half-life in kidney tissue. In addition, as an exploratory investigation, we also look at kidney imaging using MRI four months after the baseline measurement. That's after three months of treatment and then one month of follow-up. We then collect the repeat MRI, and that four-month measurement is compared to the baseline MRI to evaluate changes in height-adjusted total kidney volume, as well as total kidney cyst volume and other measures of cystic architecture. And overall, our, our expectations heading into this cohort 3, were to continue to demonstrate an increase in mechanistic activity at 3 mg/ kg using urinary polycystin, compared to 1 mg/ kg and 2 mg/ kg cohorts, as well as placebo. And now with the completion of this cohort 3, we have a similar number of total placebo patients as we have active patients in each individual cohort. So we are able, for the first time, to conduct appropriate statistical comparisons to placebo as we examine the dose response. So let's start with the baseline characteristics. We've grouped here all placebo patients in the first data column to the left, and then the active patients in each dose cohort left to right. And then finally, all active patients are combined on the far right. So the first thing to note is the number of patients in each group. There are 10 total placebo patients, nine active patients in the 1 mg/ kg group, 11 in the 2 mg/ kg group, and 12 in the 3 mg/ kg group, and 32 overall for the combination of active patients. Now, these are relatively small numbers in each group, and so we're not really surprised by or concerned about baseline differences between the treatment groups. But what we do focus on is whether these enrolled patients are the kinds of patients we want to enroll in the next pivotal phase II trial and eventually treat with commercial drug in the marketplace. And the answer here is yes, these look like patients with moderate to severe polycystic kidney disease. And that's really driven by the key inclusion criteria of the Mayo Imaging Classification score of 1C, 1D, or 1E, which defines moderate to severe PKD. And you can see the overall distribution across the Mayo classification on the second row from the bottom. And the degree of disease severity can also be gauged by looking at baseline total kidney volume and eGFR, which is shown in the two rows above the Mayo classification scores. Height-adjusted total kidney volume is between 1200 mL/m -1700 mL/m, which is more than 8x-10x the size of a normal kidney. GFR is in the high 40s-high 60s, which represents significant impairment. Now, if anything, the 2 mg/ kg cohort looks a bit milder in terms of kidney volume and GFR, and the current 3 mg/ kg cohort sits somewhere in the middle. The majority of patients enrolled have a PKD1 mutation that's shown in the bottom row, and that makes sense because 85%, 80%- 85% of disease is due to a PKD1 mutation. So again, this enrolled population that you see here represents moderate to severe PKD, and these patients have clear renal impairment and are on the path to end-stage kidney failure. They are the types of patients we plan to enroll in the next phase II pivotal trial and would hope to eventually have on therapy in the commercial market. This slide shows subject disposition across the three cohorts. As we reported earlier, one patient in cohort 2 discontinued due to a Grade 1 injection site reaction. Now, in cohort 3, out of 12 active patients, we had three discontinuations. One due to a Grade 1 ISR, or injection site reaction, similar to cohort 2, one patient who reported abdominal pain and diarrhea, and one administrative decision due to site closure. Now, this was the only patient enrolled at that site that was being closed, and unfortunately, there were no other sites within a reasonable distance to transfer the patient over to. However, in this 3 mg/ kg cohort, we were able to complete follow-up polycystin values in 11 patients and follow-up MRI scans in 10 patients. So our team has done a good job of getting as much information as possible out of the available patients. Now on to safety and pharmacokinetics. There were no significant findings in terms of safety. RGLS8429 appeared to be generally well-tolerated, and there were no specific safety signals noted. Overall, reported adverse events were similar across the three cohorts shown in the top row. And because this is an oligonucleotide delivered via subcutaneous injection, injection site reactions are important to monitor. Every oligonucleotide in clinical development has reported ISRs, and ISRs do tend to be dose-related, and we are likely seeing the same pattern here with 6 patients in the 3 mg/ kg dose reporting ISRs. Although five were reported as Grade 1, which is mild, and one was a Grade 2. We will continue to monitor ISRs as we investigate the 300 mg fixed-dose in a larger number of patients, but to date, we have not seen anything that is dose-limiting for the majority of patients. There were a similar proportion of adverse events considered to be treatment-related in the 1 mg/kg and 2 mg/kg... I'm sorry, in the 2 mg/ kg and 3 mg/ kg cohorts, mostly low-grade injection site reactions, as I just mentioned. No serious adverse events in the current 3 mg/kg cohort, and I've already mentioned the two patients in the 3 mg/kg cohort that discontinued the study early due to adverse events. Again, overall, no safety findings of concern. And I will also mention that our final fourth cohort is underway. That, again, is a 300 mg fixed dose, and we review safety data from that cohort on an ongoing basis and continue to see no safety findings of concern. And then briefly, at the bottom, in terms of pharmacokinetics, all results were as expected. There is no accumulation in plasma or urine, and the plasma AUC and Cmax increased in an approximate dose proportional manner across the 1, 2, and 3 mg/ kg cohorts. And now we'll turn to urinary polycystin results, which we again use to investigate mechanistic activity and aid us in dose finding. And because polycystin, like most other blood and urine laboratory measurements, is bounded at zero, which means there are no negative values, the data are not normally distributed and have a high right-sided positive skew or tail. To handle these non-normal data, when looking at raw numbers, we use the Wilcoxon signed-rank test. For many of the analyses, including comparing active dose to placebo, we perform the analyses on the log scale as this serves to normalize the data, and then we back-transform the results to enable straightforward interpretation. All statistical techniques are described in the slides that you'll see. We'll start by looking at individual patient responses. These two graphs show each patient's baseline and end of study polycystin value, with PC1 on the left and PC2 on the right. It's just a few things to point out here. Across placebo in the three dosing groups, baseline values are generally in the range for what is seen across Mayo Imaging Classification, 1C through 1E. The 2 mg/ kg cohort, which is in the red squares, does show a broader range in baseline urinary polycystin compared to the other groups, with 3 patients in particular having higher baseline values. and that's likely why the baseline characteristics on slide 15 suggests a bit more mild disease overall in this 2 mg/ kg group. We also see that while some of the 2 mg/ kg patients had fairly significant increases at end of study, there was more heterogeneity and spread in this group compared to, in particular, the 3 mg/ kg cohort, where a greater proportion of patients appear to be having increases. And we see the same pattern generally with PC2 on the right. The 3 mg/ kg group appears to have a more consistent response. We will take a look at this consistency of response quantitatively for both PC1 and PC2 in the next few slides. This slide shows the mean absolute change from baseline in urinary PC1 levels at each clinic visit across the study. With the absolute changes, we see mean increases for the 2 mg/ kg and 3 mg/ kg dose groups are generally similar at all time points, except for that last one at day 113, where there's a large increase in the 2 mg/ kg group and actually a reduction in the 3 mg/ kg group. We do think that 2 mg/ kg data are driven by some outlier values at day 113. As we gather more data from each cohort, we learn more about the characteristics of urinary polycystin itself. It is probably more representative to be only measuring around 2 weeks after the last dose, or in this case, through day 99, because the drug has a bit less than a 2-week half-life in the kidney. Urinary polycystin measurement is a relatively new assay that we have helped develop, and frankly, we're learning more about the right time course for measurement after dosing with each cohort that we unblind. Now, what is very important is that we see greater statistical significance in terms of change from baseline at 3 mg/ kg compared to any other group. In fact, starting with the first post-baseline measurement on day 29, the 3 mg/ kg group is significant by the Wilcoxon Signed-Rank Test and continues to be positive at all subsequent visits during this study. This speaks to a greater consistency in response. More patients are seeing polycystin increases, leading to greater statistical significance than you see with the other groups. With the absolute changes in PC2, shown here, we see a bit more variability at each dose, and so there's less statistical significance compared to what we saw on the last slide. But most of the mean increases during drug administration are highest in the 3 mg/ kg group, specifically day 29, 85, and 86. We see the confidence intervals are a bit tighter in the 3 mg/ kg group, which again suggests a more uniform response. But the most instructive and statistically robust analyses come from looking at percent change from baseline when the non-normalized data are appropriately normalized through log scale transformation. Here we have percent change in polycystin over time, PC1 on the left, PC2 on the right. We've plotted percent change at each study visit and then run a regression line through the data using a mixed model, random coefficient regression. Essentially, each patient has their own regression line calculated, and then those individual regressions are averaged together, and this helps to control for the obvious correlation over time that you observe within each patient. The results show a nice dose response in terms of percent change increase in polycystin, with the greatest response seen at 3 mg/ kg. Now, to formally compare each active dose cohort to placebo, we use that percent change from baseline to end of study. Again, the end of study is the average of all five visits from day 85 to day 113. The analyses are conducted again on the log scale, and then back transformed to account for that non-normal distribution. With PC1 on the left and PC2 on the right, we see a dose response, and as evidenced by the statistical testing in the table, 3 mg/ kg has the highest significance compared to placebo. I think something else to point out is that the increase in polycystin that we see is greater going from the 1 mg/ kg dose to the 2 mg/kg dose than it is from 2 mg/ kg to 3 mg/ kg, and this makes sense. As we discussed during the last presentation for cohort 2, we know that optimal miR-17 target engagement is achieved in a mouse at 30 mg/ kg, and that translates through allometric scaling to about 2.4 mg/kg in a human. So the 2 mg/ kg dose is likely just a bit below optimal miR-17 target engagement, and 3 mg/ kg is likely a bit above. And so we therefore expect to see some plateau of effect around 3 mg/ kg. Now, we don't necessarily expect to see much more increase in polycystin response above 3 mg/ kg, but we will be testing that in the ongoing 300 mg fixed-dose cohort. So as you've seen, we've taken a look at urinary polycystin levels a few different ways, and the message from these data are that urinary PC1 and PC2 levels demonstrate greater mechanistic activity at 3 mg/ kg, compared to the other doses and placebo. In particular, we see greater consistency of response across patients at 3 mg/ kg, and percent change increases are greatest at this dose and statistically significant compared to placebo. Along with the observed safety and tolerability profile at 3 mg/ kg, these data overall support continued evaluation of a 300 mg fixed dose of RGLS8429, which is currently underway. The final portion of the data presentation will focus on the exploratory examination of kidney imaging results using MRI. Just a bit of background for context. On average, ADPKD patients with moderate to severe disease experience around 5%-6% growth in total kidney volume over one year. Now, in this study, patients have an MRI baseline and then receive three months of treatment with study drugs, and then one month of follow-up, and then they have a repeat MRI on day 113 or four months after baseline. Over that four-month period, you would expect to see an increase in kidney volume of around 2% in untreated patients. Also for context, the only available therapy on the market, tolvaptan, demonstrated a 50% reduction in the annual growth rate of the kidney. So basically reducing a 6% per year growth rate to a 3% per year growth rate. Change in height-adjusted total kidney volume, or htTKV, is the endpoint that FDA now accepts as a surrogate endpoint for accelerated approval, and this will be the primary endpoint in the pivotal phase II trial that we expect to conduct after this current phase I-B study is complete. As I mentioned earlier, we did meet with FDA late last year to confirm the kidney volume is an acceptable endpoint for accelerated approval. Now recently, additional novel imaging techniques have been developed that provide more detail regarding cystic architecture in the kidney, including total kidney cyst volume, but these measures have not been previously utilized in a therapeutic interventional trial, so we're pleased to be able to include them in this study, although to be clear, they do not represent regulatory endpoints for approval. And finally, while RGLS8429 acts more broadly than simply polycystin, again, because miR-17 is a key control mechanism driving multiple gene networks in disease, we do know that transgenic reexpression of just polycystin in a mouse model with PKD can arrest and even reverse cystic expansion. And this raises the hope that it could potentially be possible to actually halt or reverse increases in kidney volume in patients, not simply slowing the growth. Now, this slide shows kidney imaging results using MRI. The far left plot is the percent change in total kidney volume. As you can see, due to the small numbers of patients and the wide standard deviation indicated on the plot, it is not appropriate to make direct comparisons between groups. However, we now see that mean reductions from baseline in kidney volume occur in both the 2 mg/ kg and the 3 mg/ kg cohorts. As reflected in the table in the middle, the proportion of patients with a reduction in kidney volume over just four months suggest a dose response across all treatment arms, with the greatest response at 3 mg/ kg, where 7 out of 10 patients experienced a reduction from baseline in kidney volume. We think this is highly encouraging. To round out our examination of data using that log scale transformation, as we did with polycystin, on the far right, we show that mean percent change from baseline in htTKV, and basically it gives us the same message. The 2 mg/ kg and 3 mg/ kg doses are beginning to evidence the opportunity to demonstrate reductions in kidney volume over a short treatment window. These findings are unexpected, especially given the small number of patients and the relatively short duration of treatment. Now that we've seen this response across both 2 mg/ kg and 3 mg/ kg cohorts, we believe the opportunity for RGLS8429 to have a successful outcome in the next pivotal phase II trial has been incrementally de-risked. I do want to mention that we continue to evaluate other novel measures of cystic architecture to see how they correlate with total kidney volume. Similar to what we showed with the cohort 2 data, we see that the same total kidney volume graph on the left, total kidney cyst volume in the middle, and there continues to be a tight correlation between the two, as shown in the graph on the far right. So again, this supports what we believe clinically, that changes in total kidney volume with therapy are driven by changes in cyst volume. Now, to be clear, total kidney cyst volume and other novel markers of cystic architecture are currently not part of the regulatory paradigm, but continued examination of these measures may prove to be useful over time to both regulators and clinicians. Just two more exploratory analyses as continuations of what we showed with the cohort 2 presentation, and the first one is on this slide. So with the 2 mg/ kg data, we performed a scatter plot of absolute change in polycystin and percent change in total kidney volume. We're just looking for any directional hints that mechanistic activity, in terms of polycystin, lines up with what you see clinically in terms of kidney volume. Now, this slide adds in the 3 mg/ kg data and shows changes in PC1 and total kidney volume on the left, and changes in PC2 and total kidney volume on the right. The first message we take from this relates to the 1 mg/ kg cohort in the black circle with a flat regression line. You're just not seeing any relationship between changes in polycystin and changes in total kidney volume at 1 mg/ kg. We think this is additional evidence that 1 mg/ kg is a subtherapeutic dose. On the other hand, directionally, at both 2 mg/ kg and now at 3 mg/ kg, you see an inverse relationship between polycystin and total kidney volume, where a lower rate of growth in kidney volume is accompanied by increases in polycystin. And while the number of patients is too small to enable these correlations to be statistically significant, it is interesting to note that for both PC1 and PC2, the R square value is much higher at the 3 mg/ kg dose level, suggesting greater strength of the correlation. Now, we don't anticipate any effect in estimated GFR over a short period, like three months of treatment, and as shown on the left, mean eGFR among placebo and the three dose cohorts doesn't change markedly. It was interesting to see, at least directionally, that for both 2 mg/ kg and 3 mg/ kg, there is a potential direct relationship between polycystin and GFR, where improvements in GFR are accompanied by increases in polycystin. We're encouraged to see this potential relationship, but of course, we think it will take many more patients over a much longer treatment period to confirm the impact of RGLS8429 on clinical measures of renal function like eGFR. And that work would be completed in the post-approval setting if we are able to achieve accelerated approval through a successful single phase II trial examining total kidney volume. So in summary, and this is the same summary slide I started with, looking at the totality of the data we have to date, RGLS8429 dosed every other week over three months, was well tolerated with no safety concerns. We continue to show evidence of mechanistic dose response at 3 mg/ kg compared to 1 mg/ kg and 2 mg/ kg. In particular, a more consistent response to RGLS8429 was seen at 3 mg/ kg, with more patients experiencing polycystin increases, and the percent change from baseline in both PC1 and PC2 demonstrated a dose response with statistical significance at 3 mg/ kg compared to placebo. We think that these polycystin data, along with the safety and tolerability profile demonstrated by this cohort 3, supports continued investigation with a 300 mg fixed dose, and that fourth and final cohort is currently underway. We're very excited to see continued evidence supporting total kidney volume reductions after only three months, dosing at 2 mg/ kg and 3 mg/ kg. We think this incrementally de-risks the next study, which has the potential, again, to be a single pivotal study supporting accelerated approval. I will close by reiterating that our third weight-based, placebo-controlled cohort meets expectations with respect to the key objectives of safety and tolerability, as well as mechanistic dose response. With these preliminary but very encouraging kidney imaging results, we are excited to complete our fourth and final fixed-dose cohort and also engage with FDA at the end of this year to discuss plans for a pivotal phase II-phase III program. With that, I'll turn it over to Jay to discuss next steps. Jay? Thanks, Preston. As far as next steps for the program go, we're planning to continue to mine the data and prepare for a scientific presentation at an appropriate medical conference later in the year. Additionally, cohort four enrollment is underway with several patients already in dosing and more in screening. Given it's an open label cohort, we can look at the data in batches, and we'll plan to share an update around year-end for those that have completed dosing and related analyses. We anticipate wrapping up this fourth cohort next year, but that is not rate limiting for our end-of-phase I meeting we are targeting in the fourth quarter of this year. We're busy working on focused phase II readiness activities so that we are prepared to start mid next year on the phase II study that Preston outlined. Our current planning is to conduct this phase II study with height-adjusted total kidney volume as the primary endpoint for potential accelerated approval, followed by a post-approval commitment to measure impact on GFR. There is precedent for this trial design, and we look forward to aligning with FDA on the specifics of the overall protocol at our end of phase I meeting later this year. As I said at the outset, the results from this third and final placebo-controlled weight-based cohort are highly encouraging. Again, I want to thank the patients and the investigators participating in this study, whose involvement makes these results possible. With that, we're ready to take your questions. Operator? We will now begin the question-and-answer session. To ask a question, you may press star, then one on your touch-tone phone. If you are using a speakerphone, please pick up your handset before pressing the keys. If at any time your question has been addressed and you would like to withdraw your question, please press star then two. Our first question comes from Joseph Schwartz with Leerink Partners. Please go ahead. Great, thanks very much, and, congrats on these, strong results. I was wondering if you could talk about whether you saw any changes on eGFR in the 3 mg/ kg arm, and, whether you look to see how those changes correlated with changes in height-adjusted kidney volume. Yeah, I'll go ahead and take that, and hi, Joe, thanks for the question. So, on that, one of the last data slides, I showed that just the mean eGFR over time across, you know, all the cohorts with placebo and the 3 dosing cohorts, and we essentially didn't see any real changes. That's to be expected. three months is a very short dose, you know, duration. Of course, it's a very small number of patients. We think that overall, you know, having appropriate statistical power to see differences in eGFR would require, as you've seen with other programs that have been conducted, you know, hundreds of patients over, you know, likely 2 years of therapy. So that's not necessarily, you know, surprising in terms of what we've seen. We also showed on that slide the fact that eGFR and polycystin did seem to start to have the emergence of a direct relationship, which is what you would hope to see, where increasing levels of polycystin may be associated with increases in GFR. We'll have to see how that plays out over time. And we have not to date, actually correlated eGFR with total kidney volume. That will be one of the things we're looking at as we do additional analyses and plan for a more academic presentation in the fall. Okay, very helpful. Thank you. And then, how does the data that you've reported now today change your thinking, if at all, around the size and duration of a phase two, three pivotal trial? Yeah, again, I'll take that. It's a good question. So what we talked about is generally speaking, you know, using the existing therapy, tolvaptan, and the efficacy that it's shown, both in terms of volume changes and on eGFR changes to design the phase II or phase III pivotal program. Bottom line is that when you do that, that results in around 300 subjects treated over 1 year for the volume component. That would be the phase II for a single pivotal accelerated approval, and then around 600 patients over two years for GFR. Now, as we are seeing, you know, I think we're seeing results that are far stronger than that. I think most likely it will still be prudent to plan for the numbers and duration that I was talking about. But understanding the data that we have now, and including when we see that 300 mg fixed dose data as it emerges, it may offer us the opportunity to plan in the study an early look, for example, spending a small amount of alpha to take a chance at an early win. And that could, that could, you know, if, if that were successful, actually shorten the time to approval. But I, I don't know that we would anchor on that. I think we would probably use the more prudent kind of conservative numbers that we're talking about. Makes sense. Thanks. I'll get back in the queue. The next question comes from Whitney Ijem with Canaccord Genuity. Please go ahead. Hey, guys, congrats on the data from me as well. Just wanted to follow up now that you have more patients with this cohort, looking at the second cohort and the third cohort, I guess, super responders or the patients who had the most meaningful decreases in kidney volume. Anything standing out in terms of baseline characteristics in those patients that would be relevant as you think about phase II screening criteria? Yeah. Hi, Whitney, and thanks for the question. The bottom line is the numbers are too small to really be making those kinds of comparisons. So I think it's just gonna require more for us to understand if there are certain baseline characteristics or other aspects that, you know, that kind of denote greater response. I think what we were most encouraged by... You know, we didn't know what to expect exactly going up from 2 mg/ kg to 3 mg/ kg, because, again, we're kind of straddling what we believe, based on our non-clinical work, is that optimum miR-17 target engagement. So, you know, we didn't know how much higher 3 mg/ kg would go in terms of the magnitude of increase. But the fact that the proportion of patients responding seemed to be much clearer, you know, kind of a cleaner, data set in terms of that 3 mg/ kg compared to 2 mg/ kg is really encouraging. It may well be that by pushing the dose up, a little further, you just get a better percentage of patients that do respond. And again, you know, the volume data seems to be holding out in terms of what we see at both 2 mg/ kg and 3 mg/ kg, and potentially, at least in terms of, you know, looking at the proportion of patients who had a reduction, that does seem to look like we're starting to see a nice dose response, even between 2 mg/ kg and 3 mg/ kg. So overall, I'd say everything looks really great for the 3 mg/ kg dose. We will be testing a little higher than that as we execute this 300 mg fixed dose, just based on everyone's, you know, average body weight. And so we're looking forward to seeing those results as well. ... Got it. Okay, that's helpful. And then looking towards the fourth quarter update from the fourth cohort, can you help set expectations there? I guess, how many patients do you think you'll have dosed, or what are you targeting, I guess, as part of that fourth quarter cut you'll take of that open label cohort? Thanks. Yeah. I think what we're looking at is, I mean, essentially, the timing makes sense. That's when we plan to go to the FDA with, you know, to have that discussion about the phase II, phase III program design, et cetera. We will, of course, as it's an open label study, be able to make a data cut, provide any data that we do have at that time with the 300 mg fixed dose. So that's probably the right and appropriate time to be talking about things publicly. And then, of course, we'll wrap it up, you know, when we do complete that cohort in the early part of next year. I don't wanna speculate right now. It's early days in terms of enrollment, but I, what I will say is that things are going quite well. There's a, you know, basically a significant, you know, level of interest across sites and patients in terms of this program, in part because we really are the only mid to late stage clinical program in development. And so, you know, we're seeing nice responses in terms of patients desiring, you know, screening and access into the trial. So I'm pretty, you know, excited about what we will be able to show at the end of the year, and then, of course, wrap it up early part of next year. Got it. Thanks very much for the color. Thanks. The next question comes from Yi Chen with H.C. Wainwright. Please go ahead. Thank you for taking my questions, and congratulations on the positive data. Could you comment on what percentage of TKV reduction is considered clinically meaningful from FDA's perspective, and whether you expect the fixed dose of 300 mg to achieve that level of reduction? Yeah, so, you know, essentially for accelerated approval in terms of kidney volume, what you need to show is statistical improvement in the growth rate compared to placebo. As we've mentioned, the tolvaptan program demonstrated a 50% reduction in the growth rate, so it didn't stop growth, but it did slow it. So instead of about 6% per year, you had about 3% per year. And so we're using that as kind of our baseline for our target product profile. But if what we've seen at the 2 mg/kg and 3 mg/kg dose level that we've rolled out today, you know, ends up, ends up being what we see in a larger program, that's, that's actually a very significant improvement over current standard of care. To be able to, for example, halt progression, where on average, some patients increase and some patients decrease, to have a mean, you know, reduction. A mean halting of progression of 6% compared to 0%, that would, I think, be a game changer from a clinical perspective. Got it. So given the results from the cohort 3 and also the expected medium dose for cohort 4 is 3.5 mg/ kg, so it's reasonable to expect to see more increases in PC1 and PC2 levels in cohort 4 and potentially a higher percentage of patients achieving reduction in htTKV, right? Well, I think as I said in my comments, you know, we think that the optimal target engagement dose is somewhere around 2.4 mg/kg in a human, if you just, you know, back calculate or forward calculate from what we know in our non-clinical work. And so we didn't necessarily expect to see a big difference between 2 mg/kg and 3 mg/kg, but again, at the 3 mg/kg, we're now seeing a much more consistent response, which is great. I think the rationale for the 300 mg fixed dose is to make sure that essentially, based on body weight, all patients are either at the 3 mg/kg dose level or a little bit higher. And so we'll have to see, you know, where we get to. Again, if we can just continue to show what we're showing today in terms of volume, that's a game changer from a clinical perspective, in this space. The ability to actually, on average, have a halting or even reduction in kidney volume, no one's been able to show that to date in patients. Got it. For the 30% of patients in cohort 3 that did not achieve reduction in TKV, did they at least achieve a reduction in growth rate? Well, no, I mean, that's a change in kidney volume over that four-month period of time. I think, you know, what we don't know, this is a very short period of time over which to be looking, you know, at changes in kidney volume. You're only giving the drug about three months to work. Generally speaking, you know, you don't really check kidney volume until about a year after therapy. And so we'll, you know, what we'll hope for is that over a longer period of time, we can actually even have more than 70% of patients have a reduction in kidney volume. But again, I just want to emphasize, 70% of patients having a reduction in kidney volume over just three months of treatment is pretty notable, and we're very excited about that. Got it. Thank you very much. The next question comes from Catherine Novack with JonesTrading. Please go ahead. Oh, hi. Good morning, guys. Congrats on these data. I did want to drill down again on the timeline for phase II dosing. So previously, you had projected a 12-month study, but given these results, you know, do you think FDA will still require that? Can you make any changes to the protocol based on these really rapid reductions? I know tolvaptan showed a 50% reduction, but that was over, you know, the course of a very long study. So are regulators thinking about this in terms of these rapid reductions are the key, or do they wanna see consistent reductions over time, you know, which would then necessitate a longer study? Yes, it's a very good question. I think it's, you know, early to speculate that. We'll have those conversations at the end of the year with the FDA. I think, again, you know, our general strategy has been to look at the efficacy of tolvaptan... In In terms of volume, in terms of GFR, use that as kind of our base case assumption for what we would need to execute. Again, that's about 300 patients over 1 year of treatment in a 2:1 randomization for the volume component. 600 patients over 2 years for the GFR component, and that, of course, you know, rolls out or it was wrapped up in the post-approval setting as a PMR. But what these data give us some, you know, insight into, is perhaps taking a look earlier. So again, I think it might be prudent to have your base case plan as I just laid out, but then, you know, maybe take a shot at an early look for a win, and that could significantly shave time off in terms of overall approval. Again, that's something we'll have to have a conversation with the FDA about, make sure that they are okay with that. But that's how we're thinking about the data as we see them, you know, today. Okay, great. I have another question on the patient mutational profile. You had a couple of patients in this cohort who did not have PKD1 or PKD2 mutation. What are the implications for these, you know? 15% or so of patients who don't have these mutations, is this, you know, mutation agnostic, or how did you see polycystin increases in these patients? Yeah, no, it's another good question. So what you can see in a small proportion of overall, you know, PKD patients, when you look at a large population, there are some that actually have mutations that are genes that are not specifically PKD1 or PKD2. There are some other genes, you know, in low frequency, et cetera, that essentially give the same phenotype. And it also could be the case that it's a false negative in terms of the testing, so that can happen as well. So we don't worry too much about whether that's, you know, in play or not. The important aspect of this is that when you have the PKD phenotype, that is accompanied by increases in miR-17. And miR-17, by its action, instigates this widespread gene network dysregulation. So even if it were a different gene, initiating the phenotype, miR-17, because it's increased, would come back around and latch to PKD1 messenger RNA, PKD2 messenger RNA, and hundreds of other messenger RNAs that are all involved in some fashion in controlling proliferation and cystogenesis. And it sends those out of whack and allows or enables, pushes proliferation, cystogenesis, and, you know, cyst growth within the kidney. And so, you know, we think that this mechanism is really at the right place in terms of the control point for that proliferation, you know, cell transforming, push that you get, in the disease. And so, we're just very excited about the strength of the mechanism, and we think it works across all of the genotypes. Got it. That's helpful. Thanks, guys. The final question comes from Yanan Zhu with Wells Fargo Securities. Please go ahead. Oh, great, thanks for taking our questions. So I was just wondering, if the company, you know, how does the company think about dose selection, given that the next dose is a fixed dose and it's roughly in line with the 3 mg/ kg? So mainly, I guess the question is, regarding the ISRs. Looks like 3 mg/ kg has quite a bit higher ISR rate. Although, you know, I think it's notable that it's Grade 1, but for some reason, you know, 2 patients did discontinue. So could you talk about, you know, those dynamics, and could the ISR be a consideration for the dose selection going into phase II? Yeah, sure. And what's the expectation for the fixed-dose cohort? Thank you. Yeah, no, it's a good question. The bottom line is, we're not concerned about with what we're seeing. Again, as I mentioned in my remarks, all oligonucleotides, you know, with delivered by subcutaneous injection, report ISRs, and that frequency can be reported as either, you know, anything from 100% down to 20%. And so what's important is whether or not that's rate-limiting in terms of the ability to receive and keep receiving the dose, and we did not see that, you know, to be the case. We had one patient in the 2 mg/ kg cohort discontinue, although it was a Grade 1, which is considered mild by the investigator, but if a patient decides, you know, elects to discontinue, they do. And then one patient in the 3 mg/ kg cohort. So we're not really seeing a big difference in terms of that. We did see more occurrence of Grade 1 ISRs, but again, most of those patients, five out of the six, just continued, took all seven doses, and it was not an issue. So we'll continue to evaluate this as we look at the 300 mg fixed dose. It's pretty much in line with the 3 mg/ kg dose level. Every patient will get that or a little bit higher, and so we'll just have to take a look at it and make sure. But again, we haven't seen anything that we consider to be dose limiting in terms of that, you know, that commonly noted event with injectable oligonucleotides. Great, that's very helpful. Thank you. This concludes our question and answer session, and I would like to turn the conference back over to Jay Hagan for any closing remarks. Thanks very much for your time and attention this morning. We look forward to providing updates as the year progresses. Thank you. The conference is now concluded. Thank you for attending today's presentation. You may now disconnect.