Phase 2 data: ABCL635 reduces frequency, severity of VMS symptoms

On August 10, 2026, AbCellera announced positive top-line results from the phase 2 portion of its phase 1/2 clinical trial evaluating ABCL635, an investigational neurokinin 3 receptor (NK3R) antagonist antibody. ABCL635 is being developed as a non-hormonal, long-acting, subcutaneous treatment for moderate-to-severe vasomotor symptoms (VMS) because of menopause.¹

According to a news release from the company, the study met its primary efficacy endpoints, achieving statistically significant reductions in both frequency and severity of VMS M-S at week 4 compared with placebo after a single dose.

The randomized, double-blind, placebo-controlled, multicenter phase 2 trial (NCT07118891)² enrolled 92 postmenopausal women experiencing a mean of approximately 10 moderate or severe hot flashes per day. Participants were randomly assigned 1:1 to receive a single subcutaneous 600 mg dose of ABCL635 or placebo.¹

"The [4]-week data for the phase 2 study of ABCL635 demonstrate a new efficacy benchmark for the reduction of hot flashes both in frequency and severity, as well as improvements in sleep. These symptoms can profoundly impact women's daily lives when left unmanaged. If validated in phase 3, ABCL635 could offer a new treatment option with a more convenient dosing regimen and potentially less toxicity," said JoAnn V. Pinkerton, MD, Women's Midlife Professor of Obstetrics and Gynecology at the University of Virginia School of Medicine.

Key phase 3 data of ABCL635

• Mean reduction in VMS M-S frequency of 8.8 moderate or severe events per day from baseline at week 4 (Day 29) with ABCL635, compared with 3.5 for placebo; mean placebo-adjusted treatment difference of 5.3 (P < 0.001)
• Mean percent reduction in VMS M-S frequency of 83% with ABCL635 vs 33% with placebo, a placebo-adjusted treatment difference of 50%
• Mean reduction in VMS M-S severity of 1.4 points at week 4 with ABCL635, compared with 0.3 for placebo; mean placebo-adjusted treatment difference of 1.1 (P < 0.001)
• Mean percent reduction in VMS M-S severity of 58% with ABCL635 vs 12% with placebo, a placebo-adjusted treatment difference of 46%
• Meaningful improvements observed in patient sleep scores and Patient Global Impression of Change
• No serious adverse events, severe adverse events, or adverse events leading to study discontinuation reported over the 4-week treatment period
• Most common adverse events in the ABCL635 group, occurring at higher rates than placebo: headache, fatigue, and injection site reaction
• ABCL635 targets NK3R, a G protein-coupled receptor expressed on KNDy neurons in the infundibular nucleus of the hypothalamus, and is the first program from AbCellera's GPCR and ion channel platform to enter the clinic, in July 2025

ABCL635 targets a receptor pathway tied to hot flash regulation

ABCL635 works by targeting NK3R, a clinically validated receptor involved in regulating body temperature control pathways implicated in menopausal hot flashes. The phase 2 data represent the first efficacy readout for this antibody-based approach, following the compound's entry into clinical testing in July 2025 as AbCellera's first program from its GPCR and ion channel platform.

"These positive results represent a significant milestone for women's health and for AbCellera. By successfully targeting the NK3 receptor with an antibody, we have demonstrated potential best-in-class vasomotor symptom relief over [4] weeks with a single subcutaneous dose. These data indicate that ABCL635 could offer menopausal women a well-tolerated, long-acting treatment that has the potential to markedly improve their quality of life," said Sarah Noonberg, MD, PhD, Chief Medical Officer of AbCellera.

Hot flashes and night sweats are the most common menopausal symptoms, affecting up to 80% of women, with the majority rating their symptoms as moderate to severe. VMS is the most frequent reason women seek medical care for menopause, and symptoms can persist for years after the final menstrual period, affecting sleep, concentration, energy, mood, work, and relationships. An estimated 12 million women in the United States experience moderate-to-severe VMS, and more than 6 million seek treatment for it.

What is next for ABCL635?

The reported results are top-line findings from a single 4-week treatment period following 1 subcutaneous dose; AbCellera has indicated the data will inform advancement into phase 3 testing, where the durability and consistency of the treatment effect will be further evaluated.

Reference:

1. AbCellera announces positive top-line phase 2 clinical trial results for ABCL635, demonstrating significant reduction in frequency and severity of vasomotor symptoms and a favorable tolerability profile. AbCellera. News release. Published August 10, 2026. Accessed August 10, 2026. https://www.businesswire.com/news/home/20260810931321/en/AbCellera-Announces-Positive-Top-Line-Phase-2-Clinical-Trial-Results-for-ABCL635-Demonstrating-Significant-Reduction-in-Frequency-and-Severity-of-Vasomotor-Symptoms-and-a-Favorable-Tolerability-Profile
2. Study Evaluating ABCL635 for Vasomotor Symptoms of Menopause. ClinicalTrials.gov. Updated June 15, 2026. Accessed August 10, 2026. http://clinicaltrials.gov/study/NCT07118891