Noreen Henig
Analyst · Jefferies, please go ahead
Thank you, John. First off, I'd like to echo John's sentiments regarding this stellar team that I've had the pleasure of working with for the last three months. It's been a whirlwind joining Kezar especially in the midst of a global pandemic, but the compelling and elegant science combined with the commitment to patients, that is the heart of Kezar drove me to join this dynamic and motivated team. I've always believed that hard clinical problems can be solved with increased understanding of the mechanism of the disease. What really excites me about Kezar's two lead assets KZR-616 and KZR-261 is that both have real potential to target key mechanisms of some of the hardest clinical challenges physicians and patients face, namely, autoimmune and other immune-mediated disease and cancers. Therapeutic approaches to autoimmune and neoplastic disease leave much to be desired even when they work. It's a rare opportunity to bring transformative therapies with novel mechanism and actions to patients. Turning our attention now to our clinical program. John briefly touched on the fact that in light of the new positive data we shared earlier this summer with KZR-616, combined with the slowdown in enrollment activities imposed by the COVID-19 pandemic this is a very good moment to take a good hard look at our strategy around clinical development of KZR-616. You'll recall that KZR-616 is the first in class selective inhibitor of the immunoproteasome. As the immunoproteasome is a key piece of machinery in all effector cells of the immune system, but only cells of the immune system unless disease is present is quite compelling to think that inhibition could be disease-modifying. There are many well-established animal models of autoimmune disease, and in most of them selective inhibition of the immunoproteasome is disease-modifying. We've also established through a series of studies that the effect of KZR-616 is immunomodulatory rather than immunosuppressive, which could be of significant benefit to patients with chronic immune-based disease. Today, based on safety studies with 100 healthy volunteers and 39 patients with systemic lupus erythematosus, we believe KZR-616 is a highly selective inhibitor of the immunoproteasome that has pharmacologic properties consistent with chronic administration, and that it is an active immunomodulatory drug. We will focus development on doses of 45 and 60 milligrams once per week administered via subcutaneous injection with our lyophilized formulation. I'd now like to take you through each of our three clinical programs with KZR-616 MISSION, PRESIDIO and MARINA and provide updates to the protocols and program. Let's start with Mission. As you know MISSION is a combined Phase 1b2 study of KCR-616 in patients with lupus with and without lupus nephritis. The Phase 1b portion which is 25 weeks in total, 13 weeks of dosing followed by 12 weeks observation provides important safety tolerability, pharmacokinetic and pharmacodynamic data for KZR-616. We completed enrollment of five of six cohorts exploring doses of 30 to 60 milligrams with different dosing strategies. The sixth and final cohort is evaluating the 75-milligram weekly dosing and will complete enrollment shortly. We expect the Phase 1b part of MISSION to complete in early 2021. In June, we shared some of the exciting exploratory efficacy data that we learned from the MISSION Phase 1b. In patients who receive doses of 45 or 60 milligrams weekly, there was disease improvement measured across seven indices of lupus disease activity. Most strikingly, two of two patients with active biopsy-proven proliferative lupus nephritis experienced a greater than 50% reduction in proteinuria. This was quite noteworthy, and it's worth focusing on lupus nephritis in these two patients. Lupus nephritis abbreviated LN is a severe complication of lupus and associated with significant morbidity and mortality. It is not normal or healthy to have protein in the urine. The finding of proteinuria has serious consequences for patients and is associated with renal failure. Proteinuria can be quantified by the urine protein to creatinine ratio or UPCR, which is an objective and well-known marker of disease severity and activity in LN. Reducing proteinuria significantly and quickly is the goal of therapies for LN and a 50% reduction in UPCR within six months of starting therapy is highly correlated with a long term clinical benefit. The two subjects with LN who entered this portion of the study had previously diagnosed LN that was refractory to all therapies available to them. The patients were stable enough to enroll in the 1b safety and tolerability study. In both cases, the patient experienced a drop of greater than 50% in their UPCR and did so in response to up to 13 weeks of therapy with KZR-616. These two patients also had reduced SLE disease activity scores and had supportive changes in specific biomarkers such as anti-double-stranded DNA. While a very small number of patients, the rapid and meaningful response is encouraging. The Phase 2 portion of MISSION was originally planned as a safety tolerability and dose exploration study in patients specifically with active LN and in patients who were carefully selected for their background therapy. In response to the learnings from the Phase 1b trial, the MISSION Phase 2 has been amended. The primary endpoint is now an efficacy endpoint, renal response measured by a 50% or greater reduction in UPCR at six months. We will include patients with LN with histologic Class III or IV +/1 Class V being treated with current standard of care. We plan to enroll 20 patients into this single-arm open-label trial, evaluating a target dose of 60 milligrams weekly for 24 weeks. Barring any other potential slowdown that could be imposed by COVID over the coming month, we expect to have interim data for this trial in late 2021. As a new addition, we are planning a 12-month extension study to collect data on the long term safety and durability of benefit of KZR-616. The patients to be included in this trial will reflect a range of real-world clinical situation and thus we believe we will be well-positioned to assess the benefits of KZR-616. If KZR-616 demonstrates benefit, it could represent a paradigm shift in treating patients with lupus nephritis. Let's move on to PRESIDIO which is evaluating KZR-616 in dermatomyositis abbreviated DM and polymyositis abbreviated PM to the most prevalent forms of immune-mediated myopathies. Both DM and PM are serious autoimmune diseases with significant morbidity and mortality. The existing cornerstone of therapy for these diseases is high dose corticosteroids which are associated with significant untoward effects which accumulate over time. There is a clear need for an immunomodulatory therapy that can be used chronically to control these disabling diseases. Excellent work on the pathophysiology of DM and PM shows increased presence of the immunoproteasome even in adult muscle cells where it is not usually found. Selective inhibition of the immunoproteasome with a drug like KZR-616 has been shown to be effective in animal models of immune-mediated muscle disease. PRESIDIO, which is actively enrolling, is a placebo-controlled crossover design study of KZR-616, 45 milligrams weekly in patients with DM and PM. Patients will receive 16 weeks of either KZR-616 or placebo and then cross over to receive 16 together. We are not making changes to PRESIDIO but we will be adding an open-label extension study for patients completing the trial. Our third clinical trial is MARINA, a Phase 2 trial to evaluate KZR-616 in autoimmune hemolytic anemia and immune thrombocytopenia or AIHA and ITP. Effective immediately, we are withdrawing the study. Despite the strong interest from investigators and the patient community, the decision to withdraw the study was informed by the need to substantially amend the current protocol and the COVID related slowdowns. No new clinical data-informed this decision. Our scientific conviction remains high that kZR-616 and the mechanism of selective inhibition of the immunoproteasome could be an important new therapy for patients with autoimmune cytopenia. In support of our conviction, gene signature data from the MISSION 1b study shows that KZR-616 does not down-regulate production of important hematologic cell lines, a known consequence of current or borrowed therapies for these diseases. Going forward, we can generate a new robust study designed that will incorporate our learnings about KZR-616 and current clinical practice patterns. We are working closely with key opinion leaders in the medical community to design a meaningful study to evaluate the efficacy and safety of KZR-616 in patients with AIHA and ITP with the goal of bringing a new therapy to patients as quickly and efficiently as possible. I would like to reiterate how excited I am to work with this phenomenal team and to continue to leverage the broad therapeutic potential of KZR-616 as a treatment option for a wide array of autoimmune diseases. With that, I will turn the call over to Chris Kirk, President and Chief Scientific Officer to briefly discuss our protein secretion platform and the work being done to bring our initial assets into clinical trial.