Anish Suri
Analyst · Stifel
Thanks, Matteo. Thanks, Ken. And I'd like to emphasize the key observations that Ken presented in the previous section, that have a significant impact on the evolution of the broader pipeline of assets in immuno-oncology. Most importantly, the safety, tolerability and the observed clinical activity of CUE-101 gives us bolstered confidence with the continued build-out of the IL-2-based CUE-100 series. As shown on Slide 16, the core framework, as you appreciate of the 100 series is conserved with respect to the IL-2 composition. The primary difference really swapping of the T cell epitope to change the target indication. To this end, we've continued to make very good progress with the Immuno-STAT pipeline assets that target antigens like Wilms' Tumor 1, WT1 and the mutated KRAS G12 to valine peptide that has been well-characterized by prior studies. We've recently presented these data, including most recently at the IO360 meeting last month. CUE-102, which is our next clinical candidate, targeting Wilms' Tumor 1 is slated for an IND filing in the first half of 2022. All IND-enabling activities are currently in progress and on track to meet this time line. I'd like to now focus on Slide 17. As shown here to address tumor heterogeneity, we've been developing the Neo-STAT platform to target multiple antigens or even personalized neoantigens. And to remind you, the Neo-STAT platform allows us to generate the core generic scaffold of the IL-2-based 100 series without a tumor peptide. In other words, this is an empty stabilized HLA molecule to which a desirable tumor epitope can be efficiently conjugated. This is in contrast to the classical Immuno-STATs where in each tumor epitope is a part of the fusion protein. Hence, each therapeutic molecule requires a separate cell line for generation of the clinical-grade material. So from a functional biology perspective, the Neo-STAT and Immuno-StAT molecules are very comparable as shown in the graphs on the right, with examples of T cell expansions from human blood involving 2 different antigens, CMV and MART-1. In either case, the degree of T cell expansion was very similar between the Immuno-StAT or the Neo-STAT. From a clinical application perspective, the current clinical data sets with 101 provides strong support for Neo-STATs, since again, the core IL-2 and HLA scaffold remain the same. The next slide, Slide 18, highlights an equally important derivative of the Immuno-STAT platform, which is aimed at addressing tumor escape mechanisms involving loss of tumor antigen processing and presentation components, including the loss of HLA molecules. A notable fraction of human cancers, upwards of 30%, in some cases, will undergo loss of HLA molecules, which makes them essentially invisible to tumor-specific T cells. This escape mechanism presents a significant challenge for therapeutic approaches focused on enhancing anti-tumor T cell immunity. These include checkpoint inhibitors, TCRT cell therapy approaches, tumor vaccines or even classical Immuno-STATs. Our approach to addressing this escape mechanism takes advantage of related observations from cellular analysis of human cancer tissues, revealing the significant presence of CD8 T cells that are specific for viral antigens. Such as EBV flu or CMV. In other words, a fraction of the protective memory antiviral T cell repertoire localizes to the tumor tissue likely in response to chemotactic signals that are agnostic of the specificity of the T cells. A couple of the seminal papers highlighting these findings are actually noted on the slide. These observations actually present an attractive opportunity for us to leverage the 100 series to generate a novel class of bispecific therapeutic molecules as shown in this slide, to redirect or trick the viral T cell repertoire to kill the cancer cells, including those that have lost the expression of HLA molecules. We call these new class of bispecific molecules, redirected Immuno-STATs or RDI-STATs. The RDI-STATs are essentially virus specific Immuno-STATs but contain a tumor targeting arm that allows for binding to a tumor cell surface antigen, such as a Trop2 or HER2 mesothelin, et cetera. Thus, in this manner, the tumor cell coated with a RDI-STAT molecule appears like a virally infected cancer cell, which can then be recognized and killed by the antiviral T cells that populate the host and the tumor tissue. We believe this approach has several unique advantages. It circumvents the tumors lack of HLA or antigen presentation. It harnesses a pre-existing robust antiviral T cell repertoire within the host. It's an opportunity to alter the tumor microenvironment via localizing an active immune response. From a safety perspective, this approach is very distinct from other bispecific molecules that indiscriminately activate every T cell and also result in systemic cytokine release and toxicities. And most importantly, it leverages the clinical observations provided by CUE-101, especially as it relates to the IL-2 molecules. I'd like to now move to Slide 19 to provide you an update on the autoimmune front. Our core strategy here has centered on 2 key approaches, antigen-specific and pathway-specific. The antigen-specific approach deploys Immuno-STATs to modulate autoreactive T cells and diseases with well-characterized antigens such as type 1 diabetes. In contrast, the pathway-specific approach is focused on induction and expansion of regulatory T cells for broad applications in numerous autoimmune diseases with diverse antigens or unknown antigens. As reported previously, we've been collaborating with Merck on the antigen-specific approach focused on 2 autoimmune diseases, 1 of which is type 1 diabetes, and the other is undisclosed. We've made significant progress in this collaboration, which underscore the extension of our relationship with Merck late last year to focus on optimizing potential lead clinical candidate molecules. We recently presented a progress update on these efforts via a talk at the antigen-specific tolerance meeting in January of this year. Those data slides, by the way, are available on our website. So please feel free to review those. Today, however, we would like to focus on the significant progress with the pathway-specific approach, wherein we've generated a first-in-class fusion protein containing the 2 key obligatory signals of IL-2 and TGF-beta for generation of induced regulatory T cells or Tregs. We believe this molecule also referred to as CUE-401 provides an unprecedented opportunity to reset immune balance for numerous autoimmune diseases, graft-versus-host disease and even transplant rejection. The next slide, Slide 20, provides additional insights into our focus on iTregs over the natural Tregs or also known as nTregs. The nTregs construably express the high-affinity IL-2 receptor alpha subunit, hence, many current approaches have focused on generating IL-2 variants that are biased towards the IL-2 receptor alpha, also known as CD25, to enable expansion of nTregs. In contrast, and as listed on this slide, we believe that targeting the iTregs via our approach provides a much broader opportunity and also several advantages over in nTregs. Most importantly, from a disease perspective, conversion of the pathogenic rogue repertoire of autoreactive T cells towards a regulatory phenotype as iTregs is an attractive strategy for restoration of immune balance. On the right side, you can see the design of CUE-401, which contains the 2 key signals for ITreg differentiation, an IL-2 variant and a TGF-beta variant. Importantly and in contrast to other approaches focused on nTregs, the IL-2 variant is not biased towards IL-2 receptor alpha. In fact, this is the same IL-2 that is derived from the CUE-100 series for oncology, which has been dosed successfully in human subjects and has substantive data related to the IL-2 moiety from a safety and tolerability perspective. To remind you, CUE-101, our lead clinical candidate in oncology from the 100 series has the same IL-2 except in a higher valency or 4 IL-2 molecules with an each molecule of 101 and in a different framework that targets tumor-specific T cells in that context. In contrast, CUE-401 has a single molecule of IL-2 and the end terminus of the Fc, along with the TGF-beta variant present on the C terminal are shown here for induction and expansion of induced regulatory T cells. The following Slide 21 demonstrates promising early data for CUE-401, dependent induction of iTregs from CD4 positive T cells from healthy human donors and from patients suffering from inflammatory bowel diseases, IBD, and rheumatoid arthritis, RA. note that the level of Treg induction with CUE-401 is comparable to or better than what is seen with the recombinant wild-type IL-2 and TGF-beta, as shown in the open symbols here. Furthermore, as shown in the next slide, Slide 22, iTregs induced by CUE-401 demonstrate functional suppression of polyclonal effector T cells. In these studies that were conducted with several human donors, CUE-401-induced iTregs were incubated in varying ratios with the responder effector T cells, shown as the T responder here. As you can see, iTregs induced by CUE-401, depicted by the blue symbols potently inhibit activation and polyclonal T cell proliferation stimulated with anti CD3, CD28 antibodies. In contrast, little to no suppression is noted with the non-iTreg-controlled CD4 T cells shown in red. Based on what we've accomplished so far, we remain highly committed to continue to develop this program forward towards the clinic. We believe CUE-401 could have the transformational potential for addressing the unmet medical needs for many autoimmune and inflammatory diseases. Lastly, Slide 23 connects the different pipeline vignettes and opportunities that are enabled by the CUE-101 clinical experience. The encouraging metrics with CUE-101 with respect to safety and tolerability, favorable PK and exposure, emerging PD and clinical data support multiple therapeutic opportunities as shown here. First off, it's our belief that the Immuno-StAT pipeline assets, including CUE-102, which targets Wilms' Tumor 1 and the KRAS G12 valine molecules have a reduced risk profile due to the clinical observations of CUE-101. Secondly, we also believe that the Neo-STAT platform, which is a derivative of the IL-2-based 100 series and is designed to address tumor heterogeneity also directly benefits from the CUE-101 clinical data. Third, we also believe that the development of the bispecific RDI-STATs, as I just showed you, designed to address tumor escape mechanisms of HLA loss or antigen presentation defects also derive benefit from CUE-101 since the core IL-2 framework is essentially the same. And lastly, as discussed, our novel fusion protein CUE-401 that induces regulatory T cells for autoimmune and inflammatory diseases contains a single molecule of the same IL-2 variant as incorporated into CUE-101. To summarize, we believe that the depth and richness of our growing pipeline of programs is supported by the CUE-101 clinical experience, and we very much look forward to further developments as we move these various programs towards clinical testing. With that, I'll now pass the call along to Kerri to review the financial details. Kerri?