AbCellera Reports Positive Phase 2 Results for ABCL635, Advancing Long-Acting Non-Hormonal Treatment for Menopausal Hot Flashes
AbCellera has announced encouraging top-line results from the Phase 2 portion of its ongoing Phase 1/2 clinical trial evaluating ABCL635, an investigational antibody designed to target the neurokinin 3 receptor (NK3R) for the treatment of moderate-to-severe vasomotor symptoms associated with menopause. The findings mark an important development milestone for the biotechnology company as it advances a potential non-hormonal and long-acting therapeutic option for women experiencing frequent and disruptive hot flashes.
The Phase 2 study achieved both of its primary efficacy endpoints, demonstrating statistically significant reductions in the frequency and severity of moderate-to-severe vasomotor symptoms at Week 4 compared with placebo following administration of a single subcutaneous dose. In addition to reducing hot flashes, ABCL635 was associated with improvements in sleep and patient-reported overall health status, measured through the Patient Global Impression of Change (PGI-C).
Vasomotor symptoms, commonly referred to as hot flashes or night sweats, are among the most recognizable and frequently reported symptoms associated with menopause. For many women, these symptoms can occur repeatedly throughout the day and night, interfere with sleep, affect daily activities, and negatively influence overall quality of life. The development of effective therapies that can provide sustained symptom relief without relying on hormonal treatment remains an important area of unmet medical need.
ABCL635 is being developed as a non-hormonal, long-acting antibody treatment administered by subcutaneous injection. The program is based on targeting NK3R, a receptor involved in the neurobiological pathways that regulate thermoregulation and are believed to contribute to menopausal vasomotor symptoms.
Phase 2 Trial Demonstrates Significant Reduction in Hot Flashes
The randomized, double-blind, placebo-controlled, multicenter Phase 2 portion of the clinical trial enrolled 92 postmenopausal women who were experiencing moderate-to-severe vasomotor symptoms. At baseline, participants reported an average of approximately 10 moderate or severe hot flashes each day, highlighting the substantial symptom burden experienced by the study population.
Participants were randomized equally to receive either a single 600 mg subcutaneous dose of ABCL635 or placebo. Researchers then evaluated changes in the frequency and severity of vasomotor symptoms over the treatment period.
At Day 29, corresponding to Week 4, patients treated with ABCL635 experienced a mean reduction of 8.8 moderate-to-severe vasomotor events per day from baseline. This compared with a reduction of 3.5 events per day among patients receiving placebo.
The resulting placebo-adjusted treatment difference was 5.3 events per day, with the difference reaching a high level of statistical significance at p<0.001. The results also showed a substantial relative reduction in symptom frequency. Patients receiving ABCL635 experienced an average 83% reduction in the frequency of moderate-to-severe vasomotor symptoms from baseline at Week 4, compared with a 33% reduction in the placebo group.
This represented a placebo-adjusted difference of 50 percentage points, reinforcing the potential of ABCL635 to provide meaningful symptom control after a single administration.
The frequency results were complemented by improvements in symptom severity, another key consideration for patients living with menopause-related hot flashes.
Improvements in Symptom Severity
In addition to reducing the number of hot flashes, ABCL635 produced a statistically significant improvement in the severity of vasomotor symptoms.
At Week 4, the mean reduction in symptom severity was 1.4 points among patients receiving ABCL635, compared with a 0.3-point reduction in the placebo group. The resulting placebo-adjusted treatment difference was 1.1 points, with a p-value below 0.001.
The percentage reduction in symptom severity further demonstrated the difference between the treatment groups. Patients receiving ABCL635 experienced a 58% reduction in severity from baseline to Week 4, while patients receiving placebo experienced a 12% reduction. This generated a placebo-adjusted difference of 46 percentage points.
Taken together, the frequency and severity findings indicate that ABCL635 was not simply associated with fewer hot flashes but also with a reduction in the intensity of symptoms that remained.
“These four-week data demonstrate a new efficacy benchmark for the reduction of hot flashes both in frequency and severity, as well as improvements in sleep,” said Dr. JoAnn V. Pinkerton, Women’s Midlife Professor of Obstetrics and Gynecology at the University of Virginia School of Medicine. She noted that vasomotor symptoms can significantly affect women’s daily lives when they remain untreated and suggested that, if confirmed in Phase 3, ABCL635 could potentially provide another treatment option with a convenient dosing approach and potentially less toxicity.
Sleep and Quality-of-Life Measures Also Improved
The impact of menopausal vasomotor symptoms frequently extends beyond the immediate discomfort of hot flashes. Symptoms that occur during nighttime can interrupt sleep, contribute to fatigue, and affect concentration and daily functioning.
In the Phase 2 study, meaningful improvements were also observed in patient sleep scores among individuals receiving ABCL635. Improvements were additionally reported in the Patient Global Impression of Change, indicating that patients perceived an overall improvement in their condition during treatment.
These patient-reported outcomes could become an important component of future development because they provide information about whether reductions in symptoms translate into tangible benefits for everyday life.
For women experiencing recurrent moderate-to-severe hot flashes, the potential to reduce both symptom frequency and intensity while improving sleep could represent an important therapeutic advantage.
Favorable Four-Week Safety Findings
Alongside the efficacy results, AbCellera reported that ABCL635 was well tolerated during the four-week treatment period evaluated in the study.
No serious adverse events were reported in the ABCL635 treatment group. There were also no severe adverse events and no adverse events that resulted in treatment discontinuation.
The most commonly reported adverse events occurring at a higher frequency in the ABCL635 group compared with placebo were headache, fatigue, and injection-site reactions.
While longer-term studies will be necessary to establish the broader safety profile of ABCL635, the initial four-week findings provide an encouraging foundation for continued clinical development.
Potential Advantages of an Antibody-Based Approach
ABCL635 represents a different approach to treating menopausal vasomotor symptoms because it uses an antibody to target NK3R rather than relying on hormone replacement.
The investigational therapy is also designed for long-acting administration. If the clinical profile demonstrated in Phase 2 is confirmed in later-stage studies, a less frequent dosing schedule could offer convenience compared with treatments that require daily administration.
AbCellera Chief Medical Officer Sarah Noonberg, M.D., Ph.D., described the findings as a significant milestone for both the company and women’s health. She said the results demonstrate the potential of targeting NK3R with an antibody to deliver substantial relief from vasomotor symptoms after a single subcutaneous dose.
According to the company, the findings suggest that ABCL635 could potentially provide menopausal women with a well-tolerated and long-acting treatment capable of improving quality of life.
Next Steps in Clinical Development
The positive Phase 2 results represent an important step as AbCellera evaluates the potential of ABCL635 in a larger clinical development program. Although the results are encouraging, the company will need to generate additional clinical evidence before the therapy’s safety and efficacy can be fully established.
Later-stage clinical development will be particularly important for determining the durability of symptom relief, evaluating safety over longer treatment periods, confirming the magnitude of benefit in broader patient populations, and assessing the appropriate dosing strategy.
The company’s development strategy will also need to demonstrate that the benefits observed in the Phase 2 trial can be reproduced in larger and potentially more diverse populations.
ABCL635’s progress comes as researchers and pharmaceutical developers continue to explore alternatives for women who cannot use hormone therapy, prefer non-hormonal treatments, or require additional options to manage persistent menopausal symptoms.
With its focus on NK3R and a long-acting antibody format, ABCL635 could potentially occupy a differentiated position within this emerging therapeutic landscape if future trials confirm the Phase 2 findings.
AbCellera also planned to discuss the results with investors during a conference call and webcast on August 10, 2026. The company said a replay of the event would be made available through its investor relations platform.
Overall, the Phase 2 findings provide AbCellera with positive momentum for the ABCL635 program. The combination of statistically significant reductions in both the frequency and severity of moderate-to-severe vasomotor symptoms, improvements in sleep and patient-reported outcomes, and favorable short-term tolerability supports continued investigation of the therapy.
As AbCellera moves toward subsequent stages of development, the focus will be on determining whether these early findings translate into durable clinical benefits and a clinically meaningful treatment option for women affected by menopause-related vasomotor symptoms.
About ABCL635
ABCL635 is a potential best-in-class investigational antibody drug for the non-hormonal, long-acting treatment of moderate-to-severe VMS, commonly known as hot flashes, due to menopause. ABCL635 specifically targets NK3R, a clinically validated G protein-coupled receptor (GPCR) expressed on KNDy neurons in the infundibular nucleus of the hypothalamus. ABCL635 is AbCellera’s first pipeline program from the GPCR and ion channel platform to advance into the clinic, in July 2025. Additional details are available at www.abcellera.com/pipeline.
The Phase 2 trial of ABCL635 (NCT07118891) is a multicenter, randomized, double-blind, placebo-controlled trial in postmenopausal women with moderate-to-severe VMS due to menopause evaluating safety and efficacy of ABCL635.
About VMS
Hot flashes and night sweats, known as VMS, are the most common menopausal symptoms, impacting up to 80% of women. The majority rate their VMS as moderate to severe, characterized by intense feelings of heat that lead to sweating, chills, and interrupted sleep. VMS are the most frequent reason for seeking medical care for menopause. VMS can persist for many years after the final menstrual period, and the impact is felt across many aspects of everyday life, including sleep, concentration, energy and mood, work, social activities, and relationships. It is estimated that approximately 12 million women in the US experience moderate-to-severe VMS, of which more than six million seek treatment.
About AbCellera Biologics Inc.
AbCellera (Nasdaq: ABCL) is a clinical-stage biotechnology company focused on discovering and developing first-in-class antibody-based medicines in the areas of endocrinology, women’s health, immunology, oncology, and more. For more information, please visit www.abcellera.com.