Terence Rooney
Analyst · JPMorgan
Thanks, Nello. It's a pleasure to join you all today to review the positive Phase I results for KT-579. As a rheumatologist by training, I'm particularly excited by what we've demonstrated with this program. The translation from the strong preclinical profile into humans is an important milestone and validates our confidence both in the biology and the potential of IRF5 degradation as we prepare to move KT-579 into patients. I'll start with an overview of the Phase I study design and the demographics of the healthy volunteers enrolled in the study. I'll then walk through the PD data, beginning with the depth and durability of IRF5 degradation in blood. Next, I'll cover the functional consequences of that degradation across 3 distinct IRF5-dependent immune pathways assessed using disease-relevant ex vivo stimulation assays. And finally, I'll review the safety profile observed and then discuss how the totality of these data inform our plans to advance KT-579 into lupus patients. As we've been saying for some time, primarily for competitive reasons, in some areas of the presentation, we're sharing only limited data. As shown on Slide 12, the Phase I study was designed to characterize the safety, PK and PD of KT-579 following both single and multiple ascending doses in healthy volunteers. We evaluated a range of doses up to 600 milligrams in the MAD cohorts. In the SAD portion of the study, 8 subjects per cohort were randomized 6:2 to receive a single oral dose of KT-579 or placebo. In the MAD portion, 12 subjects per cohort were randomized 9 to 3 to receive once-daily oral KT-579 or placebo for 14 days. While the primary objective of the study was to evaluate the safety and tolerability of KT-579, the study was also designed to establish proof of mechanism in humans. In both SAD and MAD, we evaluated IRF5 degradation across dose levels. And in the MAD portion, we also assessed the downstream functional consequences of IRF5 degradation using disease-relevant ex vivo stimulation assays measuring inflammatory biomarkers. Together, these endpoints allow us to address the key questions we set out to answer in the study. First, can we safely achieve deep and sustained degradation of IRF5 with KT-579? Second, does that degradation translate into the expected functional impact on IRF5-dependent biology. And as you'll hear today, the answer to both questions is yes. Turning to Slide 13, the demographics of the volunteers enrolled in the SAD and MAD portions of the study. Overall, there were no meaningful imbalances in baseline characteristics that would impact our interpretation of the study results. Now before turning to the MAD degradation data, although it's not shown in this presentation, we did want to mention that KT-579 exhibited the predicted PK profile with dose responsive exposures in SAD and MAD cohorts. Additionally, while we generated degradation data across both the SAD and MAD portions of the study, we're only sharing the MAD degradation data here as repeated daily dosing most closely reflects the intended clinical use of KT-579. Now looking at Slide 14, which illustrates degradation across MAD dose cohorts with data shown at day 7 and 14. The top 5 dose cohorts all reached median IRF5 degradation greater than 90% with saturation of degradation by dose level 3 with blood degradation achieving 94%. Importantly, while not shown, we also observed comparable reductions in IRF5 levels in skin, demonstrating target degradation in tissue as well as blood. Overall, KT-579 demonstrated robust degradation of IRF5 at or above levels predicted by our preclinical work in both the SAD and MAD. And this profile shows that the target remains continuously suppressed with once-daily dosing, providing sustained pharmacologic coverage of IRF5 expression. Now in addition to degradation, we also assess the impact of IRF5 degradation on downstream biomarkers, which we believe is an important indicator of the potential biological effects. As a reminder, IRF5 has a role in the regulation of three major immune pathways relevant to several autoimmune diseases. These include, first, inflammatory cytokines. IRF5 promotes the production of key inflammatory cytokines by myeloid cells, including monocytes and macrophages. And when dysregulated, these responses can sustain chronic inflammation. Second, interferon response. IRF5 helps connect nucleic acid sensing with interferon production and associated gene expression responses. Dysregulation of this pathway can amplify immune activation and inflammation. And the third pathway is B-cell biology. IRF5 contributes to B-cell activation and pathways associated with plasma blast differentiation and autoantibody production. So this breadth of biology is an important feature of the IRF5 mechanism. By degrading IRF5, KT-579 has the potential to modulate multiple interconnected drivers of inflammation through a single oral approach. Now to assess this biology in healthy volunteers, we use three orthogonal ex vivo stimulation assays that our team developed internally. These assays activate distinct RNA and DNA sensing toll-like receptor pathways and measure downstream changes in inflammatory mediators and gene expression. This allowed us to assess whether IRF5 degradation translated into functional effects across all three key areas. And in the following slides, we'll focus on the impact of IRF5 degradation demonstrated in each pathway. In each graph, we'll show the median of all KT-579 MAD dose cohorts combined compared to placebo. So shown here on Slide 16, IRF5 degradation translated into deep and sustained inhibition of core inflammatory cytokines, including TNF alpha, IL-12 or 23 p40 and IL-1 beta. And as shown here, median cytokine reduction across all MAD cohorts combined ranged from 87% to as high as 94%. The kinetics of cytokine inhibition track with the kinetics of IRF5 degradation and the magnitude of the effect is consistent or superior to what was observed preclinically. These reductions are particularly encouraging as this is the core pathway involved in lupus through TLR7/8 and in IBD through TNF alpha and interleukin -12/23, two of our highest priority indications. We interrogated the same inflammatory cytokine pathway more broadly with transcriptomics. The transcriptomics provide a complementary confirmation of the cytokine data, showing modulation of IRF5-dependent inflammatory biology. So anonymized, the heat map shows the changes in selected pathway genes with placebo and across all KT-579 dose cohorts at day 14 in relation to their respective pre-dose sample, while the graph quantifies the overall modulation of the gene set. We observed strong gene to protein concordance with genes like TNF alpha and interleukin-12 moving in the same direction as the corresponding functional cytokine readouts as described in the previous slide. The second major axis we tested was interferon response, another important component of IRF5-dependent inflammation and a particularly relevant pathway in heterogeneous diseases. The effect on this pathway cytokine is particularly pronounced. We demonstrated near complete reductions in TLR7/8 stimulated interferon beta levels with the MAD dose cohort showing a median inhibition of 98%. Importantly, the transcriptional data independently support and extend this result, showing modulation results in broad coverage across key interferon pathway genes. And these data validate the pharmacology beyond the inflammatory cytokine pathway we showed in the prior slides, demonstrating that IRF5 degradation can translate into profound functional modulation of the interferon axis, which is well recognized as overactive in the biology of several autoimmune disorders, including lupus and Sjogren's disease. Finally, as shown on Slide 19, the effects of KT-579 reach into the third major axis of IRF5, B-cell biology. Selected TLR9-driven transcripts are significantly modulated with KT-579, including key genes associated with DNA sensing and B-cell activation, again, important steps in the pathogenesis of autoimmune diseases, including lupus. In summary then, KT-579-driven IRF5 degradation translates into coherent functional modulation across three major pathways we set out to interrogate, inflammatory cytokines, interferon response and B-cell biology. And that breadth of pharmacology is one of the key takeaways from this first-in-human data set. Okay. Moving to safety. KT-579 was well tolerated and had a safety profile comparable to placebo. As shown here on Slide 20, there were no serious adverse events, very few mild treatment-related adverse events, no adverse events leading to discontinuation of study drug or from the study and no clinically relevant changes in vital signs, lab tests or ECGs. There are also no imbalances in the rate of infections. It's very encouraging that KT-579 was able to robustly degrade IRF5 in blood and also functionally modulate disease-relevant biomarkers across 3 key immune pathways while demonstrating a placebo-like safety profile. The Phase I data represents an important milestone for KT-579 for our IRF5 program and for Kymera. These results established important human proof of mechanism for KT-579. We've demonstrated that we can achieve deep and sustained degradation of IRF5 with an oral medicine with a favorable safety and tolerability profile. Importantly, we've also seen that IRF5 degradation translates into strong and encouraging downstream effects on the disease-relevant inflammatory biology. So taken together, this gives us increased confidence that we're achieving the profile we designed KT-579 to deliver and provide a strong foundation to move into patients. As the program following our STAT6 efforts, IRF5 is yet another example of Kymera's ability to develop potentially transformational medicines for patients. So on that note, we now plan to advance KT-579 into its first patient study in lupus. Lupus remains an area of significant unmet need, where many patients continue to cycle through therapies without achieving adequate or durable disease control and treatment often requires combinations of immunosuppressive agents with meaningful safety and tolerability limitations. We see significant opportunity for a new safe and effective oral therapy. Lupus is a compelling indication for this program given their strong genetic evidence linking IRF5 to lupus and IRF5 plays a central role in lupus disease biology. We've previously shown disease-modifying activity in multiple preclinical lupus models. And as you've seen today, we've now demonstrated exciting biomarker data suggesting a strong connection between IRF5 degradation and three important disease-relevant pathways. So this gives us a high degree of confidence in the underlying biology and a clear rationale for evaluating the impact of IRF5 degradation directly in patients. The planned Phase Ib study will allow us to begin answering the next important questions, whether IRF5 degradation and downstream biology we observed in healthy volunteers carry through to patients with lupus and whether KT-579 can affect the disease pathways that are active in those patients. In healthy volunteers, we measure pathway effects after stimulating blood samples ex vivo, while in patients we'll be able to assess those effects in the setting of active disease as well as look for early signs of clinical benefit. We view this as an important next step for the program and towards establishing IRF5 degradation as a potentially new therapeutic approach for patients with autoimmune disease. Here's a snapshot of the Phase Ib study designed for the trial, which we've named LUMORA. We plan to enroll approximately 30 patients with SLE randomized 2:1 to KT-579 or placebo and treated for 16 weeks. Oral corticosteroid background therapy is permitted. In fact, our upcoming oral presentation at the American College of Rheumatology Conference demonstrates that KT-579 shows significant activity alone or in the presence of background therapies in preclinical lupus models. The Phase Ib will evaluate the impact on inflammatory cytokines, interferon signatures, B-cell subsets and other key immune pathways implicated in lupus. And we'll also explore measures of lupus disease activity, including changes in mucocutaneous and musculoskeletal symptoms that patients experience. In this small Phase Ib study, those measures will help us look for early signs of clinical activity alongside the safety and biomarker results. So with that, I'll turn the call over to Bruce.