Helen Thackray
Analyst · Stifel. Your line is now open
Thank you, Rachel. The data that will be presented at ASH is quite extensive, especially as it relates to the uproleselan Phase I/II abstract and the supporting data on E-selectin as a mechanism of resistance in AML. I'd like to begin by underscoring some of the key takeaways. First, I'd like to emphasize that the new data set from the Phase I/II study includes data from the final locked database. It includes extended follow-up for survival in patients past the time point initially specified in the protocol. We opted to amend the protocol to extend the duration of follow-up and to provide a final data set that now includes fewer patients with censored data for survival, the result of which is our increased confidence in the key efficacy endpoints that underpin our GMI and NCI-sponsored registration programs. Secondly, we now present – for the first time – data on measurable residual disease, or MRD, in each of these AML cohorts as we believe uproleselan selectively disrupts the relationship between leukemic cell and the bone marrow micro environment. We would expect to see a higher percentage of those patients who achieve complete remission to be MRD negative. I'm pleased to report that this is exactly what we see in our clinical trial. Over 50% of the evaluable patients in both the relapsed/refractory and newly diagnosed cohort achieved this stringent level of disease response. Thirdly, correlative data on E-selectin ligand expression on leukemic blasts and leukemic stem cells show that this target is highly relevant, particularly in the relapsed/refractory patient population with higher levels of E-selectin ligand expression correlating with both response and survival in this cohort of patients treated with uproleselan. These data on expression, combined with the data on MRD negativity, further support our underlying hypothesis that E-selectin is a driver of resistance in AML. If we can disrupt binding of cancer cells to this target, we believe the results will be improved clinical outcomes. And lastly, at ASH, our collaborators at the Fred Hutchinson Cancer Center will also be presenting independent clinical data, demonstrating that E-selectin ligand expression on leukemic blasts correlates with poor outcomes in AML. Specifically, the work by Dr. Pam Becker shows that E-selectin binding is fourfold higher for patients with relapsed/refractory leukemia compared to patients with newly diagnosed leukemia, suggesting that sequestration of leukemic cells in the vascular niche of the marrow is a key factor in chemotherapy resistance. One particularly interesting observation in this data set is that E-selectin ligand expression was significantly upregulated in FLT3-mutated AML. These data support the use of our E-selectin antagonist in this high-risk AML population, potentially as a way to further improve the antitumor activity of FLT3 inhibitors. We will certainly be exploring ways to capitalize on this new clinical finding. Now, I'll speak to some of these observations in greater detail. As a reminder, in the Phase I/II study, we enrolled two groups of patients, in each case adding uproleselan to standard induction and consolidation chemotherapy. In one arm of the study, we enrolled 66 patients with relapsed or refractory AMLs, of whom 54 were treated at the recommended Phase II dose. In the other arm, we enrolled 25 newly diagnosed patients. I'll comment on each of these separately. Starting with the relapsed/refractory cohort, we enrolled a group of patients who had very high-risk disease. Two-thirds of the patients enrolled in this arm were either primary refractory or had relapsed within the initial six months of prior chemotherapy. In addition, 50% of the patients enrolled had adverse cytogenetics as determined using ELN criteria. In our Phase III trial, the primary efficacy endpoint in which we will seek approval is overall survival, or OS, the global regulatory standard – both standard endpoints. And so, I will start then by reviewing that data from the Phase I/II. In the abstract released yesterday, we report a final median OS of 8.8 months. As described previously, this magnitude of clinical benefit compares very favorably to historical demographically matched controls for which OS varies between 5.2 and 5.4 months. While we believe that OS best captures the full benefits of uproleselan, it is important to note that we observed meaningful improvement across a number of key endpoints, reflecting both the potential safety and efficacy of the drug. In the abstracts, we report a 41% complete remission rate, either CR or CRi; 9.1-month duration of remission; a low 2% incidence of severe, grade 3/4 oral mucositis; and now, for the first time, that 69% of evaluable patients achieved MRD negativity as assessed by rigorous methods using flow, RT-PCR or next-gen sequencing. We’re very encouraged by this high rate of MRD negativity and the fact that this deep threshold of remission translated into 73% one-year overall survival for this subset of patients with high-risk disease. This is a great outcome. Since the MRD evaluation was done after only one cycle of treatment, we think there is a real opportunity to drive those rates of MRD negativity higher by treating patients with additional cycles of uproleselan. This is exactly what we are doing in our pivotal Phase III trial. Specifically, we are offering additional cycles of consolidation with uproleselan in responding patients, with the goal of achieving a deep remission that could further extend overall survival. Turning now to the newly diagnosed population, for the NCI's Phase II registration study, an interim analysis of the first 250 patients will be conducted to evaluate EFS differences between the investigational arms. Therefore, I'll start by reviewing the data on EFS here. In this cohort of patients 60 years of age and older with newly diagnosed AML, we treated 25 patients with uproleselan plus standard induction chemotherapy, known as 7 plus 3. I'd like to emphasize that, while these patients have not been treated for AML previously, they – like the relapsed/refractory group – had very high-risk disease. 48% of patients had adverse risk cytogenetics and 52% had secondary AML upon study entry. In the data released yesterday, we report a median event-free survival of 9.2 months in this high-risk population. This outcome compares favorably to historical EFS data with 7 plus 3 alone, which ranges from approximately 2 to 6.5 months. Notable in historical data, I would argue these data were reported in patient populations that had lower-risk leukemia than the patients enrolled in our study. I say this based on their lower rates of secondary AML and lower rates of adverse cytogenetics in the patients studied. These are disease characteristics known to affect risk of refractory disease, early relapse and early death. Therefore, we believe that the EFS outcome in this high-risk population strongly supports the selection of EFS as the primary endpoint measure for the NCI trial’s interim analysis. In addition to EFS, we report internally consistent and supportive efficacy outcomes when uproleselan is added to 7 plus 3. Specifically, we observed a very high overall remission rate of 72%, including 69% remission rate in patients with secondary AML, an extended duration of remission of 10.6 months and a median overall survival of 12.6 months. Additionally, and for the first time, we also report new data on measurable residual disease, MRD, with 56% of evaluable patients achieving this high-threshold remission. Again, by offering up to four cycles of therapy in the NCI trial, we hope to deepen responses as reflected in high MRD negative rates. If achieved, this would be expected to improve survival outcomes. In summary, the data released yesterday in the ASH abstracts provide strong support for the use of uproleselan in the treatment of AML. It also provides additional justification for the study designs and primary endpoints in both the relapsed/refractory and newly diagnosed registration trials. With that, I'll stop there and hand it back over to Rachel.