Jim Dentzer
Analyst · B. Riley Securities. Please go ahead with your question
Thank you, Bill. Good afternoon everyone and thank you for joining us today. At Curis, we're focused on developing the next generation of targeted cancer therapies that will meaningfully improve and extend patients' lives. In the second quarter of 2021, we made concrete progress towards that goal and laid the foundational groundwork to expand into additional areas where we believe we can make a difference. As a reminder, our lead asset, a novel small molecule IRAK4 inhibitor called CA-4948 is currently being evaluated in nine distinct patient populations, two AML and MDS populations in monotherapy for patients with spliceosome or FLT-3 mutations, two AML and MDS populations in combination therapy of CA-4948 with azacitidine and venetoclax, and four B-cell cancer populations in combination therapy of CA-4948 with ibrutinib. In addition, we are working with Dr. Uwe Platzbecker of the University of Leipzig on the LUCAS IST to study CA-4948 in monotherapy in patients with lower risk MDS. As many of you have been following, the long isoform of IRAK4 or IRAK4-L has been identified as the key driver of disease in the majority of patients with AML and MDS. Curis has the most advanced drug that directly targets IRAK4 in clinical testing for these patients. With each new batch of beta, our excitement for CA-4948 grows even further with its manageable and predictable safety profile and demonstrated ability to show deepening efficacy, the longer patients remain on treatment. At the EHA meeting in June, we were especially pleased to share updated data from the monotherapy arm of the Phase 1/2 AML and MDS study, highlighting efficacy at multiple study doses, a potentially differentiating factor that may enable us to help even the most extremely sick patients in this historically underserved population. Our second program, our first-in-class monoclonal anti-VISTA antibody, CI-8993, has also been making good progress. We've been pleased with patient enrollment in the Phase 1 dose escalation study in relapsed or refractory solid tumors and are on track to provide a substantive initial report on safety by year-end, including what we hope to be signs of early success in managing the CRs side effects known to be associated with anti-VISTA therapy. All told we continue to progress through 2021 as a year of execution for Curis. With that, let's dig into some detail on our ongoing programs, starting with the IRAK4 program in leukemia. At EHA earlier this summer, we were pleased to present updated data from the monotherapy arm of our AML and MDS study, which reinforced previously observed findings of single agent efficacy across the spectrum of late-line AML and MDS patients despite these patients having already experienced several unsuccessful prior lines of therapy. As a reminder, the data in our EHA presentation identified a subset of patients with specific genetic mutations that make their disease highly amenable to treatment with CA-4948 based on the drug's mechanism of action. Of the four evaluable patients with a spliceosome or FLT-3 mutation, all four achieved an objective response. This early success provides a key validation of the scientific thesis that U2AF1 and SF3B1 spliceosome mutations are specific drivers of the oncogenic long isoform of IRAK4, which CA-4948 is explicitly designed to target. In the broader patient population, in those patients without a spliceosome or FLT-3 mutation, we also saw encouraging signs of efficacy. Nine of 11 evaluable patients in this group achieved tumor reduction or were able to maintain a blast count in the normal range. The next step in our clinical plan is to address this population in combination therapy of CA-4948 with azacitidine or venetoclax. We hope that CA-4948 with its unique mechanism of action and demonstrated disease modifying capability will prove an important addition to the combination therapy toolset in the battle against AML and MDS. The data presented at EHA also highlighted the strong safety profile of CA-4948 with no dose limiting toxicities related to myelosuppression and no overlap in dose limiting toxicities with azacitidine or venetoclax, which are planned were combination studies with CA-4948. The dose limiting side effect at higher doses consisted of uncomplicated rhabdomyolysis, or elevated CPK and muscle soreness, which was manageable, quickly and easily detected, readily reversible and did not limit further treatment at a reduced dose level. Of note, those patients who did experience rhabdomyolysis at higher doses generally had predisposing factors such as taking statins or strenuous exercise. And lastly, we were also pleased to report at EHA an update of the pharmacokinetic analysis for CA-4948. At the 300 milligram b.i.d. dose, we are achieving pharmacokinetic exposure in patients that correlates to 98% target inhibition in preclinical models. These impressive data further our confidence in CA-4948 as a novel and robust IRAK4 inhibitor that has the potential to significantly advance therapeutic options for patients with AML and MDS. In first-line patients whose bone marrow has not been irrevocably damaged by cancer or by prior cytotoxic treatment, it has been shown that clear and substantial hematologic recovery is achievable within a few months if leukemic blast levels are effectively reduced. In contrast for the late line patients in our study, it is important to remember that they already have deeply scarred dysfunctional marrow, which may delay or even prevent successful hematologic recovery. CA-4948 like other cancer therapies addresses the underlying cancer, but it is not by itself a marrow stimulating agent. We are therefore very pleased to see signs of hematologic recovery in these extremely sick patients after only a few months of treatment. From a regulatory perspective, our goal is to have 10 to 20 patients with spliceosome mutations on drug by year end. Assuming the data remained consistent we hope to be in a position to reach out to the FDA in the first half of next year to discuss the potential for our rapid approval path. Given the compelling data observed to date, and the impressive pace of enrollment we are optimistic that we can meet this goal. The spliceosome population is only one of the nine population groups we are studying with CA-4948, but we believe these may be the data which mature the quickest, enabling the earliest discussions with FDA. While the monotherapy studies push ahead the incremental positive safety findings showing no overlapping dose limiting toxicity with azacitidine or venetoclax were an important next step in the development of CA-4948 in combination therapy for the broader population of AML and MDS patients. These findings underscore the relevance and importance of the updated preclinical data also presented at EHA, which highlighted CA-4948 synergistic antitumor activity when used in combination with azacitidine and venetoclax in leukemia cell lines. Before moving on from leukemia, I would like to briefly touch on the ongoing Phase 2 LUCAS IST for patients with lower risk MDS, being led by the Co-Chairman of EHA's Scientific Working Group on MDS, Dr. Uwe Platzbecker. As a reminder of the study's rationale, if successful, it could lead to a potential breakthrough in the MDS field. Current standard of care with EPO stimulating agents can be effective for patients with lower-risk MDS. However, this effect is often transient, it is not disease modifying and it does not affect further disease complication and progression to AML. With its direct targeting of IRAK4 and strong safety profile, we believe CA-4948 could potentially offer a safe and disease modifying alternative for patients at earlier stages of disease. With that let's move on to lymphoma. We reported updated clinical data from our Phase 1 dose escalation study of CA-4948 for the treatment of patients with relapsed or refractory NHL or other hematologic malignancies at ASH last December. These data highlighted durable reductions in tumor burden in six of seven evaluable patients treated with 300 milligrams of CA-4948, twice daily, following a median of four prior lines of therapy. It is important to reiterate it seemed clear efficacy with a novel monotherapy agent and seeing that this efficacy is durable over such an extended period of time for these extremely sick patients is enormously encouraging and provided powerful affirmation of our intention to launch the current combination study evaluating CA-4948 with ibrutinib. As a reminder, enrollment in the combination study began in Q1 of this year with CA-4948 doses starting at 200 milligrams and escalating to 300 milligrams BID. We expect to report initial data from this study at a medical meeting in the first half of 2022. Lastly, I'd like to turn toward VISTA program with CI-8993, our first-in-class monoclonal antibody for the treatment of patients with relapsed or refractory solid tumors. We believe CI-8993 is the most advanced anti-VISTA antibody currently in clinical development and has the potential to be a game changing cancer therapy. In June, we hosted a virtual symposium gathering industry taught leaders and respected academics to discuss the emerging understanding and opportunities surrounding this immune checkpoint. The excitement and interest in our program in both the clinical and academic communities is very high, and we look forward to reporting an initial update by year end. Briefly, I'd like to give you a sense of why we're so excited about this program. Existing major checkpoint inhibitors function to enhance T-cell priming such as anti-CTLA4 antibodies or relieve T-cell exhaustion, such as anti-PD-1 or PD-L1 antibodies. All of these have two key limitations. First CTLA4 and PD-1 checkpoints cannot act on T-cells that are stuck in a quiescent state. Second, it is known that CTLA4 and PD-1 effectiveness is actively impaired by myeloid-derived suppressor cells or MDSCs which promote T-cell exhaustion and suppress pro-inflammatory macrophages. In VISTA, we find the checkpoint whose primary role is enforcing T-cell quiescence. In addition, VISTA is a known driver of MDSCs with this dual pronged effect VISTA can sequester a large proportion of T-cells in a quiescent state and prevent them from being acted upon by anti-CTLA4 or anti-PD-1 antibodies. Finally, we know that the expression of VISTA can increase dramatically as a compensatory mechanism during treatment with anti-CTLA4 or anti-PD-1 or PD-L1 therapy. For these reasons, we believe that therapeutic targeting of VISTA will be a crucial addition to the immune oncology arsenal. To wrap-up, I'd like to extend my utmost appreciation to the entire Curis team who continue to work tirelessly in pursuit of these paradigm altering breakthroughs. We're eager to build upon our efforts in the quarters to come and advanced our next generation targeted cancer programs to help patients in need. With that, I'll turn the call over to Bill to review our financial results for the quarter. Bill?