Briggs Morrison
Analyst · Cowen. Chris, your line is now open
Thank you, Melissa and thank you to everyone for joining us on today's call and webcast. Slide 3 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.We recently announced two significant updates for our lead program. First, the ECOG Data Safety and Monitoring Board has communicated to us that E2112 has passed its last interim analysis and will proceed to its final analysis at 410 events. This brings us closer to a potential near-term FDA filing, approval, and launch in hormone receptor positive metastatic breast cancer.The second important event is that we have begun dosing patients in our Phase I AUGMENT-101 trial of our highly selective rationally designed Menin inhibitor SNDX-5613. As a result of this accomplishment, we are now entering a new and exciting chapter in the evolution of Syndax.The SNDX-5613 program takes us into the treatment of genetically defined acute leukemias and importantly, broadens our portfolio. Both programs have the potential to become important new medicines. We expect to know much more about the future prospects of both entinostat and SNDX-5613 over the next six to 12 months.So, let's review these opportunities in some greater detail. Slide 4 summarizes the design of the Phase III 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 clearly on the final overall survival analysis.The final analysis will be conducted once there are 410 events. Based upon our modeling, we believe that the final readout of E2112 based on the full 410 events will occur sometime in the second quarter of next year.Positive outcome would allow us to file for regulatory approval in the U.S. based upon the terms of our breakthrough therapy designation in hormone receptor positive metastatic breast cancer and our special protocol assessment with the 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.As we have now successfully passed five utility analyses and are poised for the final readout of the trial, I'd like to take a moment to remind everyone of the assumptions that were used in the design of the E2112 study. 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 of 0.82.Based upon the design assumptions, if E2112 reached a hazard ratio of 0.82; that would indicate that patients receiving the combination had about a five-month improvement in median overall survival from about 22 months median overall survival in the control arm to about 27 months median overall survival in the combination arm.Our market research indicates that this magnitude of benefit in overall survival is perceived by prescribing physicians to be important and clinically meaningful. We remain confident in the potential for E2112 to be a positive trial.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 single agent or in combination with a CDK4/6 inhibitor. Our current estimate is that between a third and half of the patients in 2112 will have received a CDK4/6 inhibitor prior to entering our trial. Thus we should have a highly relevant data set 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 antiestrogen therapy.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 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 and we are actively building out our internal commercial team to ensure we are well positioned for the potential launch of entinostat in 2021.Let me now turn to SNDX-5613 our genetically targeted agent. Yesterday, we announced the exciting news that the first patient tested dose in the AUGMENT-101 trial. I'll review that trial shortly, but first I'd like to provide a brief overview of SNDX-5613.Slide 6 summarizes the biology that underlies the development of SNDX-5613. Mixed Lineage Leukemias are driven by a fusion protein known as MLL-r. This fusion protein is half derived from MLL1 and half derived from a variety of fusion protein partners.For the fans of Greek mythology, you can think of the fusion protein as a Centaur, mythological creature that is half-human and half-horse. The MLL half of the fusion protein binds to Menin, a scaffolding protein involved in activating transcription, while the other half is responsible for recruiting a cancer-producing transcription program.This interaction between Menin and the MLL1 half of the fusion protein has been defined at the molecular level. And as illustrated on Slide 7, SNDX-5613 has been rationally designed to block this interaction. SNDX-5613 is a potent and specific orally available small molecule.Slide 8 is an illustration of how the fusion protein causes cancer and how SNDX-5613 should work. In the left panel, we see the MLL1 portion of the fusion protein bound to Menin and fusion partner half of the protein attracting a multi-protein complex to DNA. This results in activation of a family of genes that cause cancer.In the panel on the right, you can see that SNDX-5613 binds to Menin displacing the fusion protein and its accompanying multi-protein complex. The genes that were activated are turned off and the cancer cell differentiates and dies.We've presented extensive preclinical data showing that this mechanism has potent and sustained anticancer effects in numerous in-vivo models of both MLL-r leukemias and NPM1 mutant leukemias.On Slide 9 we summarized the first-in-human trial in what we call the accelerated understanding of Menin inhibition or AUGMENT program. The first-in-human clinical trial is a combined Phase I/Phase II trial. The Phase I portion is a dose escalation trial designed to identify the maximum tolerated dose and a recommended Phase II dose of SNDX-5613.Patients with relapsed or refractory acute leukemia will be enrolled and will take SNDX-5613 daily by mouth until they experienced either progressive disease or unacceptable toxicity.The first 28 days of dosing will serve as the period in which safety is evaluated for determining dose escalation. Patients are not required to have specific genetic abnormalities in order to enroll in the Phase I portion of the study.The first cohorts follow an accelerated dose titration with only one patient required per cohort. Upon entering a pre-specified label -- upon encountering a pre-specified level of toxicity, the trial will convert to a standard 3+3 design. We will carefully assess pharmacokinetics, safety and efficacy.It is anticipated that upwards of 30 patients maybe enrolled in the Phase 1 portion with the precise number dependent on the number of cohorts that need to be explored and the toxicities that are encountered. We announced this week that enrollment in the AUGMENT-101 trial has commenced with our first patient in the first single patient cohort.I want to emphasize that the PK analysis is a key component of the Phase 1 trial. Our preclinical data indicates that the Menin-MLL-r interaction needs to be continuously inhibited in order to achieve optimal efficacy. And so, we will be carefully examining the drug exposures in patients to assess whether we are indeed achieving adequate target coverage.We look forward to seeing these initial PK data in the first dose cohorts as those data will significantly inform the likelihood and timing of single-agent efficacy in the MLL-r rearranged and NPM1 mutant leukemic population. Given that patients are not required to have specific genetic abnormalities in order to enroll in the Phase 1 portion of the trial, we believe that PK data from the Phase 1 portion could be more informative than the efficacy assessments with efficacy being an exploratory objective.Furthermore, we believe that safely achieving adequate target coverage in the Phase I trial could bode well for establishing efficacy in the Phase 2 portion. Once the recommended Phase 2 dose is established, the Phase 2 trial will proceed to enroll three distinct expansion cohorts, each of which consists of a specific genetically defined relapse or refractory acute leukemia.The three cohorts are adults with MLL-r acute lymphoid leukemia ALL; adults with MLL-r acute myeloid leukemia AML; and adults with NPM1 mutant CML. 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.We know that a lot of people, patients, physicians and investors are eager to see initial data from the first AUGMENT trial. Given that we are just getting the trial up and running, it's not possible to provide specific guidance as to when we will present data. As of now, we expect to report initial clinical data from the trial in 2020. We should be able to give you a better sense of the data timing as the trial progresses.In addition, we are eager to advance this molecule into the pediatric population. It is a key component of our overall strategy. And we will have more to say about the details of the pediatric timing and approach on a future call. We know pediatric leukemias with MLL-r rearrangements represent a significant unmet medical need, and we're eager to work with the pediatric oncology community to bring SNDX-5613 to their patients.Based upon preclinical data and the underlying biology of the pathway, we are expecting evidence of single-agent activity. As a result, there could be a rapid and straightforward clinical development path for 5613, perhaps similar to the path taken for agents addressing patients with FLT3 or IDH mutations. As we continue to learn more about the potential of SNDX-5613 in acute leukaemia, we see this molecule becoming an additional and important value driver for Syndax.Let me now turn to slide 10 and SNDX-6352, our potential best-in-class monoclonal antibody therapy targeting the CSF-1 receptor. We are conducting a trial testing 6352 as monotherapy in chronic graft-versus-host disease. Chronic graft-versus-host disease is a frequent complication of hematopoietic stem cell transplantation wherein the donor-derived immune cells contribute to the initiation and development of fibrosis and manifestation of many of the advanced disease symptoms.In preclinical models, blockade of the CSF-1, CSF-1R axis with an antibody, it can result in the depletion of donor macrophages thereby preventing and reducing chronic graft-versus-host disease. We believe that chronic graft-versus-host disease represents an important clinical opportunity.I mentioned on our last call that when our IND was cleared for the study, the FDA required that we limit enrollment to patients whose disease had progressed after both steroids and ibrutinib therapy. However, as ibrutinib is not currently frequently used to treat this population, enrollment has been a bit slower than anticipated. We've now worked with the FDA to modify the enrollment criteria, and we are now in a position to enroll a broader set of patients. We hope to provide an update on this program in the second half of next year.Finally, slide 11 summarizes transactions that led to the acquisition of the Menin MLL-r program and the SNDX-6352 program. 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 that we have the necessary clinical development expertise to bring these compounds through valuable inflection points and expect to remain among preferred partners of such transactions.I will now turn the call over to Rick, who will review our financial results.