Eric Siemers
Analyst · BTIG. Go ahead with your question
Thanks, Dan, and good morning, everyone. We continue to work diligently as we near the finish line of our Phase I trial. As Dan highlighted, the totality of the data from INTERCEPT-AD will be important for choosing doses for subsequent studies of ACU193. This includes data on Safety, CSF PK, and CSF target engagement. As I mentioned on our last call at the end of March, the assay for our target engagement is designed to measure the complex of A-Beta oligomers bound to ACU193, and CSF. We have since run preliminary assay tests using CSF from patients which have increased our confidence that the assay is performing as intended. Recall that oligomer concentrations in CSF are generally reported to be less than 2pM, which means that our target engagement assay must be very sensitive. We also anticipate announcing exploratory data with our topline results from our Phase I study, including Cogstate computerized cognitive testing as well as arterial spin labeling pull sequences on MRI, which will determine if cerebral blood flow has increased after treatment with ACU193. While these analyses are exploratory and may not result in a clear signal in this small study with a short duration of treatment, these techniques maybe employed in the subsequent larger clinical trial using ACU193. As a reminder, we have included typical clinical measures like the CDR sum of boxes and the ADAS-Cog in our Phase I study. However, because this is a small, short study, it is unlikely that those measures will show a drug effect. During the first quarter, our team also presented a poster at AD/PD in Sweden that demonstrated the utility of a human in vitro model of induced pluripotent stem cell-derived excitatory neurons for a better understanding of which forms of A-beta oligomers contribute to the pathogenesis of AD in the human brain. This study found that soluble A-beta size may influence synaptic binding, low molecular weight 5-way beta species such as monomers, dimers and trimers, demonstrated the lowest levels of detectable synaptic binding compared to those of mid and high molecular weight defined as greater than 150 kilodaltons. We believe that these research efforts can contribute to the development of next-generation therapies with higher selectivity for toxic soluble amyloid species that are the most relevant to Alzheimer's type of genesis such as ACU193. Finally, the success of donanemab in the TRAILBLAZER II study announced last week, provides further scientific support for the amyloid beta hypothesis broadly. These results build on the success of lecanemab reported in the Phase III CLARITY trial. While broadly speaking, these antibodies are both related to the amyloid hypothesis, there are important differences between them. Donanemab targets deposited amyloid plaques and reduces plaque load substantially with dosing every four weeks. Lecanemab targets A-beta protofibrils, but also reduces plaque load with every two-week dosing. The rate of ARIA-E with donanemab in TRAILBLAZER-ALZ 2 was reported to be 24%. While for lecanemab, the rate of ARIA-E was reported to be 12.6%. For both antibodies, about 20% to 25% of ARIA-E cases were symptomatic. We believe that ACU193, targeting oligomers has the potential to have lower rates of ARIA-E with equal or better efficacy compared to donanemab and lecanemab. We applaud the well-run study results from TRAILBLAZER-ALZ 2 in clarity that solidify forward momentum in the field. While these treatments are a good first generation start, ACU193 may further improve the benefit risk profile of a disease-modifying treatment for patients and families navigating Alzheimer's disease. And with that, I'll turn the call over to Matt.