Carl L. Hansen
Analyst · Steve Seedhouse with Cantor
Thanks, Tryn, and thank you, everybody, for joining us today. Q3 was a transformative quarter for AbCellera, driven primarily by our positive top line Phase II results for ABCL635, which is an investigational antibody for the nonhormonal treatment of moderate to severe vasomotor symptoms or hot flashes. The Phase II study was designed to evaluate efficacy and safety at 4 weeks following a single 600-milligram injection of ABCL635. The data, which we announced on August 10, show that ABCL635 has strong potential to redefine the standard of care for nonhormonal treatment of hot flashes. On the strength of these data, we have an exciting opportunity to develop a potential category-defining women's health product with clear differentiation across efficacy, safety and convenience. In line with this, we believe our data also significantly expands the commercial prospects for ABCL635, and we are fully committed to bringing it into late-stage development next year. In the next few slides, I'll review the key results and put them into context with respect to existing therapies. Our first key efficacy endpoint was reduction in the frequency of moderate and severe hot flashes. This slide shows the effect of ABCL635 plotted as change from baseline values using both the primary analysis on the left, which included only values from weeks 2, 3 and 4, as well as a prespecified sensitivity analysis on the right that included week 1 data as well. I first note that our data shows rapid onset of benefit with a significant placebo-adjusted treatment difference of 2.6 events already present at week 1 and then increasing improvements over the full 4-week period. At 4 weeks, the ABCL635 group has a mean reduction of 8.8 events per day compared to a mean reduction of only 3.5 events per day in the placebo group, representing a placebo-adjusted treatment difference of 5.3 events. Expressed as a percent change from baseline, the ABCL635 group experienced an 83% reduction from baseline in daily events compared to a 33% reduction in the placebo group for a placebo-adjusted treatment difference of 50%. Notably, the benefit of ABCL635 was highly consistent across subgroup analyses and the data were robust to a variety of sensitivity analyses. Our second key efficacy endpoint was reduction in the severity of VMS, which is reported on a 3-point scale, representing mild, moderate and severe events. As with frequency, we see a rapid onset of benefit with significant improvement at the 1-week time point and increasing improvement out to 4 weeks. At 4 weeks, the mean severity scores decreased by 1.4 points in the ABCL635 group versus 0.3 points for the placebo group for a placebo-adjusted difference of 1.1 points. When expressed as a percent change from baseline, the ABCL635 group experienced a 58% mean reduction in severity from baseline compared to a 12% mean reduction in the placebo group for a placebo-adjusted difference of 46%. As an alternative to reporting population averages, another valuable way to look at the data is to assess the fraction of patients that experienced different ranges of treatment benefit. In the table on the left, you can see that 37% of ABCL635 participants had complete or 100% resolution of moderate or severe events at 4 weeks. This is compared to only 2.2% of placebo patients. To our knowledge, these levels of complete resolution of moderate and severe events have not been reported for any non-hormonal VMS treatments and are at least comparable, if not superior, to reports from studies of hormone therapy. Furthermore, nearly 61% of ABCL635 participants had at least a 90% improvement from baseline in the number of moderate to severe events compared to only 8.7% of placebo patients and a full 78%, more than 3/4 of patients, at over 75% reduction. These large and clinically meaningful benefits were also observed for severity as shown in the table on the right. While acknowledging the potential limitations in making cross-trial comparisons, it is worth evaluating our observed treatment effects against data collected similarly at 4 weeks from the registrational studies of the 2 approved small molecule NK3R antagonists, fezolinetant and elinzanetant. Looking at the placebo-adjusted reduction in frequency of moderate and severe VMS expressed as a percentage of the baseline levels, our placebo-adjusted treatment effect is 50%, which is approximately twice as large as the 20% to 25% reductions reported in Phase III studies of fezolinetant and elinzanetant. An even greater difference in treatment effect was observed in improvements in VMS severity with a roughly 3.5 to fivefold greater benefit as compared to the registrational studies of fezolinetant and elinzanetant. Importantly, these markedly enhanced treatment effects were achieved without any clear signal of gastrointestinal or liver toxicity. This slide summarizes adverse events reported in at least 2 patients in either treatment group, regardless of relationship, occurring during the first 4 weeks of treatment. ABCL635 demonstrated a favorable tolerability profile across the data set. Overall, there was a numerically higher number of patients with at least 1 adverse event in the ABCL635 group compared with the placebo group. There were no serious or severe adverse events in the ABCL635 group compared to 1 placebo patient with a serious adverse event and 2 placebo patients with severe adverse events. Similar to the data in the Phase I study, ABCL635 was associated with an increased incidence of headache with the majority rated as mild and transient across both treatment groups. Fatigue was also reported more often in the ABCL635 group, although all events were mild. Importantly, we did not see any evidence of gastrointestinal toxicity in this study despite it being consistently reported with the 2 approved small molecule NK3R inhibitors. In fact, we observed a lower incidence of nausea in the ABCL635 group and no events of diarrhea or abdominal pain compared to multiple patients reporting these events in the placebo group. Summing up, our Phase II data showed a combination of breakthrough efficacy and favorable tolerability. Based on this, we believe ABCL635 has the potential to redefine the standard of care for nonhormonal treatment of hot flashes. Looking forward, we are committed to advancing ABCL635 into late-stage development and are actively working through the FDA's model-informed drug development, or MIDD, program to gain alignment on dose selection for subsequent studies. We expect to disclose additional data through 12 weeks and the open-label extension, or OLE, data in early 2027. As a reminder, in terms of efficacy, the primary objective of the Phase II trial was to evaluate the benefit of a single dose of ABCL635 over the course of 4 weeks. This is the data we have just reviewed. The remaining portion of the 12-week data is to monitor the decline in efficacy over the final 8-week washout period with this data used to support exposure response modeling for late-stage dose selection. Following the initial 12-week period, OLE data will provide an additional 4-week assessment, allowing us to characterize repeat dose dynamics in the treatment group alongside initial active exposure in the placebo group. We expect to initiate late-stage development for menopause, VMS, in 2027. And in parallel, we are expanding the indications for ABCL635 to include hot flashes caused by hormone suppression associated with breast and prostate cancer treatment, and we expect to initiate clinical trials in these 2 populations in 2027. Finally, today, we are pleased to announce a new program, ABCL992, which is the next-generation half-life extended analog of ABCL635. ABCL992 entered IND-enabling activities in Q3. Building on our landmark data from ABCL635, we believe this program will advance another therapeutic option that provides even greater convenience to patients through extending dosing interval and facilitates broader patient reach. Moving on from ABCL635. And as previously guided, today, we are presenting Phase I results from our second clinical candidate, ABCL575, which is a long-acting investigational antibody targeting OX40 Ligand. ABCL575 entered clinical development as a potential best-in-class follower of Sanofi's amlitelimab, which at the time was in Phase III studies for atopic dermatitis. Earlier this year, based on disappointing clinical data, development of amlitelimab was discontinued in atopic dermatitis. Separately, late-stage clinical studies of Amgen's rocatinlimab, an OX40-targeted antibody, also led to discontinuation. Based on these external results, we will not pursue development of ABCL575 in atopic dermatitis. And while we believe the OX40, OX40 Ligand class has potential in other autoimmune conditions, we do not currently have plans to develop it beyond Phase I. With that, I'll hand it over to Sarah to discuss our top line results from the Phase I study. Sarah?