Briggs Morrison
Analyst · Christopher Marai, Nomura
Thank you very much, Melissa, and thank you to everyone joining us on today's call and webcast. Before we get started, I'd like to take a moment to acknowledge that we are actively monitoring the ongoing COVID-19 pandemic to assess any potential impacts to our business.Our number one priority is of course, the health and safety of our employees, as well as the patients and medical professionals involved in our ongoing clinical programs.At this time, we do not anticipate any interruption or delays to our ongoing clinical programs, nor do we expect any impact on our financial guidance. We will continue to monitor the evolving situation, and we'll provide updates as necessary.Let us now turn to Slide 3, which provides a high-level summary of our current corporate priorities, as we strive to realize a future, in which people with cancer live longer and better than ever before. As we had anticipated, 2020 is turning out to be a tremendously exciting and transformative year for our company.Since our last call in March of this year, we have presented the first clinical evidence that inhibition of the menin-MLL1 interaction by SNDX-5613, our Menin inhibitor can induce response in patients with MLL-r acute leukemias and we announced the successful addition of approximately $100 million to our balance sheet under attractive terms.Moreover, the final overall survival readout of E2112 will occur this quarter, bringing us closer to a potential near-term FDA filing, approval and launch in hormone receptor-positive metastatic breast cancer.Finally, we continue to collect data that will further clarify the potential of our anti-CSF-1R antibody, axatilamab to treat chronic graft-versus-host disease.So let's review each of these opportunities in greater detail. Slide 4 summarizes the design of the Phase 3 trial of entinostat in hormone receptor-positive HER2-negative breast cancer. The trial randomized 608 patients to exemestane, plus placebo versus exemestane plus entinostat and the focus of this trial is now on the final overall survival analysis.The final analysis will be conducted once there are 410 events, which, based on our modeling and recent discussions with ECOG, we believe will occur before the end of June this year. A positive outcome would allow us to file for regulatory approval in the United States, based upon the terms of our breakthrough therapy designation in hormone receptor-positive metastatic breast cancer and our special protocol assessment with FDA.Our team is prepared to submit a regulatory filing, should the trial be positive within about six months of receiving the data from ECOG, which would set us up to launch entinostat in 2021. The trial has 80% power to detect a hazard ratio of 0.75 and the maximum hazard ratio that would yield a statistically significant positive trial is approximately 0.82.Based upon the design assumptions, if E2112 achieved a hazard ratio of 0.82, that would indicate that patients receiving the combination had about a five month improvement in median overall survival.Slide 5 emphasizes the potential for the entinostat-exemestane regimen to be the preferred agent after a first-line aromatase inhibitor, which is typically given either as a single-agent or in combination with a CDK4/6 inhibitor.Our current estimate is that between 30% and 50% of patients in E2112 will have received a CDK4/6 inhibitor prior to entering the trial. Thus, we should have a highly relevant dataset in the post-CDK4/6 patient population.In our opinion, the rapid adoption of CDK4/6 inhibitors, such as Ibrance in the first-line setting, underscores the desire of physicians and patients to improve the outcomes associated with anti-estrogen therapies. In the setting of a positive E2112 result, we would expect entinostat to achieve similar widespread use.This population of patients is substantial with an estimated 34,000 patients in the U.S. each year who go on to receive hormone therapy after failing first-line therapy and who could, therefore, be eligible to receive the entinostat regimen.Importantly, we will be prepared to launch entinostat in the U.S. on our own. We are actively building out our internal commercial team to ensure we are well-positioned for the potential launch of entinostat in 2021, while currently entering into discussions with potential rest-of-world commercial partners.Slide 6 emphasizes the clinical potential of entinostat in hormone receptor-positive breast cancer. In preparation for launching entinostat, we have conducted qualitative market research with community physicians and breast cancer experts. We tested a conservative profile, essentially the minimum benefit that could provide a positive OS result in E2112.We consistently heard from both groups of physicians that there is a high need for novel agents in hormone receptor-positive breast cancer and that they find the potential ability of entinostat to resensitize patients to endocrine therapy to be a very attractive feature of entinostat.Not surprisingly, they uniformly saw overall survival as the most important efficacy endpoint and believe that an agent that could extend survival and lengthen the patients' time on hormone therapy with minimal impact to their quality of life made a very compelling profile.We remain confident in the potential for E2112 to be a positive trial and are eager to bring this potentially important new medicine to patients.Let me now turn to Slide 7 and SNDX-5613, our genetically targeted agent. On our last call, we highlighted two premier publications, one in Cancer Cell and one in Science that provides a scientific rationale and preclinical validation of our ongoing clinical trial.Those publications did not involve the use of our development candidate, SNDX-5613. Therefore, we were quite excited to be selected to present the preclinical profile of SNDX-5613 at the AACR New Drugs on the Horizon Session last month. I will not review the details of that presentation, it is available on our website, but I will summarize a few key points.First, our molecule is a potent and specific inhibitor of the menin-MLL interaction. The only off-target activity of note is its relatively weak binding to the HER channel. And second of clinical relevance, SNDX-5613 is metabolized by CYP3A4.On Slide 8, we summarize the detailed experiments that were conducted to derive a model of the plasma exposures we think will be needed in patients to drive efficacy.We were, of course, pleased that, as shown on Slide 9, the second patient in the trial and the first patient in the trial with an MLL-r rearrangement had plasma exposures that exceeded the levels we anticipated would be required for efficacy and indeed went on to achieve a complete response. Importantly, clinical activity was observed rapidly by day 28 of therapy.No dose-limiting toxicities were observed and the only treatment-related adverse experience was a grade-two QTc prolongation. Of note, this patient was on a concomitant medication that inhibits the activity of CYP3A4, which may account for the disproportional PK exposure relative to what we had anticipated.Full details on additional patients are included in the AACR presentation that's available on our website.The updated first-in-human trial in the Accelerated Understanding of Menin Inhibition or AUGMENT program is the AUGMENT-101 trial and is shown schematically on Slide 10. This first-in-human clinical trial is a combined Phase 1 and Phase 2 trial.The Phase 1 portion is a dose-escalation trial designed to identify the maximum tolerated dose and a recommended Phase 2 dose of SNDX-5613 in two independent cohorts of patients with relapsed or refractory leukemia.Arm A enrolls patients who are not on a strong CYP3A4 inhibitor and Arm B enrolls patients who are on a strong CYP3A4 inhibitor at the time of enrollment. The first 28 days of dosing serves as the period in which safety is evaluated for determining dose escalations.As required by the FDA, patients do not need to have a specific genetic abnormality to enroll in the Phase 1, 2 study. As of the time of the AACR presentation, we have completed our evaluation of cohorts one and two in Arm A and are evaluating a single patient at dose level three.No dose-limiting or grade-two toxicities have been observed to-date. And at the time of the AACR presentation, in Arm B, we had no dose-limiting toxicities and have expanded to a three-plus-three design given one grade-two toxicity.Our intent is to define a recommended Phase 2 dose for each cohort. Once the recommended Phase 2 doses are established, a Phase 2 trial will proceed to enroll three distinct expansion cohorts, each of which consists of a specific genetically-defined relapsed or refractory acute leukemia.The three cohorts are, adults with MLL-r Acute Lymphoid Leukemia, or ALL, adults with MLL-r Acute Myeloid Leukemia, or AML, and adults with NPM1 mutant AML. Our intent is to have specified dosing guidelines for patients in Phase II derived from these two cohorts in Phase 1.The Phase 2 portion will further characterize the safety of SNDX-5613 and will provide an initial estimate of the complete response rate as the primary measure of therapeutic benefit. Additional updates from the Phase I portion of the AUGMENT-101 trial are anticipated in the fourth quarter of this year at a medical conference. We do not anticipate any further updates before the fourth quarter.In addition, we are eager to advance this molecule into the pediatric population as a key component of our overall strategy. We will have more to say about the details of the pediatric timing and approach on our future call.We know pediatric leukemias with MLL-r rearrangements represent a significant unmet medical need and we are eager to work with the pediatric oncology community to bring SNDX-5613 to their patients.Let me now turn to Slide 11 and axatilamab, formerly known as SNDX-6352, our potential best-in-class monoclonal antibody therapy targeting the CSF-1 receptor. Results from the multiple-ascending dose trials exploring axatilamab alone and in combination with durvalumab in patients with solid tumors were presented last week during the virtual AACR meeting.These results demonstrated the tolerability and robust pharmacodynamic biomarker modulation of axatilamab and underscored its ability to promote rapid and sustained depletion of circulating pro-inflammatory monocytes at all dose levels tested.As you know, we initiated a trial testing of axatilamab as monotherapy in chronic graft-versus-host disease and the rationale for using a CSF-1R inhibitor against this disease as shown on Slide 12. Chronic GVHD is a frequent complication of hematopoietic stem cell transplantation, wherein donor-derived immune cells contribute to the initiation and development of fibrosis and the myriad manifestations of the disease.In preclinical models, blocking the CSF-1, CSF-1R pathway with anti-CSF-1R antibody can result in the depletion of donor macrophages, thereby preventing and reducing chronic graft-versus-host disease. We believe chronic GVHD represents an important clinical opportunity.Last year, we released the initial data from our Phase 1 trial, which is diagrammed on Slide 13. The Phase 1 portion is a dose-escalation trial designed to identify the maximum tolerated dose and a recommended Phase 2 dose of axatilamab for the treatment of chronic graft-versus-host disease.We have released the data from the first five patients enrolled in the first three cohorts and have now modified the trial to include a Phase 2 cohort at the one milligram per kilogram dose. We will continue the Phase 1 trial to formally define the recommended Phase 2 dose and may open one or more additional Phase 2 dose cohorts, as well.Finally, Slide 14 summarizes the transactions that led to the acquisition of the Menin-MLL-r and axatilamab programs. We believe that we will be able to continue to expand our pipeline through the acquisition or in-licensing of quality differentiated assets.We believe we have the necessary skill to evaluate and identify high-quality assets and the clinical development experience to bring these compounds through valuable inflection points. We expect to remain among preferred partners of such transactions.I'll now turn the call over to Rick to review our financial results. Rick?