Connect Biopharma Presents Data Supporting Development of Rademikibart at the American Thoracic Society (ATS) 2025 International Conference

Rhea-AI Summary

Connect Biopharma (NASDAQ: CNTB) presented promising data for rademikibart, their next-generation IL-4Rα antibody, at the ATS 2025 International Conference. The Phase 2b trial results showed significant improvements in lung function (FEV1) within 24 hours and reduced acute exacerbations in asthma patients. The drug demonstrated particular efficacy in patients with elevated eosinophil counts. Notably, rademikibart showed a superior safety profile compared to dupilumab, with approximately 30% decrease in eosinophil counts at Week 24, versus dupilumab's 50-120% increase. Structural analysis revealed rademikibart's optimized binding to IL-4Rα, with ~60° rotation compared to dupilumab, resulting in stronger and more stable interaction. Phase 2 studies in asthma and COPD are ongoing with topline data expected in 1H26.

Positive

• Significant improvement in lung function (FEV1) within 24 hours of treatment
• Superior safety profile with 30% decrease in eosinophil counts vs. 50-120% increase with dupilumab
• Enhanced IL-4Rα inhibition compared to dupilumab due to optimized molecular structure
• Strong efficacy in COPD-like patients, particularly those with elevated eosinophil counts
• Significant reduction in acute exacerbations in type 2 inflammatory asthma patients

Negative

• Phase 2 topline data not expected until first half of 2026
• Results based on post-hoc analyses, which are generally considered less robust than pre-planned analyses

Insights

Immunology & Respiratory Medicine Specialist

Connect Biopharma's rademikibart shows rapid lung function improvement and structural advantages over dupilumab, positioning it as potential best-in-class IL-4Rα inhibitor.

The data presented by Connect Biopharma at ATS 2025 reveals several clinically significant advantages for rademikibart that differentiate it from existing IL-4Rα inhibitors like dupilumab (Dupixent). The most striking finding is the rapid onset of action, with improvements in FEV1 (forced expiratory volume) observed within just 24 hours of administration—a critical advantage for patients experiencing acute exacerbations. This rapidity could represent a paradigm shift in managing asthma and COPD flares.

The post-hoc analyses demonstrate particularly robust efficacy in patients with elevated type 2 inflammatory biomarkers (eosinophil counts ≥300 cells/µL and FeNO ≥25 ppb). This patient stratification approach aligns with current understanding of asthma endotypes, suggesting rademikibart could be especially effective in the eosinophilic phenotype that typically responds well to biologics.

What's mechanistically fascinating is the structural difference revealed through X-ray crystallography. Rademikibart binds to IL-4Rα with an approximately 60° rotational difference compared to dupilumab, creating more hydrogen bonds and demonstrating lower B-factors. This molecular distinction explains the enhanced receptor binding affinity (reportedly >2-fold higher than dupilumab) and improved downstream STAT6 signaling inhibition.

Perhaps most clinically relevant is the differentiated effect on eosinophil counts. While dupilumab is associated with hypereosinophilia (50-120% increases), rademikibart actually decreased eosinophil counts by approximately 30% at 24 weeks. This suggests a fundamentally different immunological impact despite targeting the same receptor, potentially eliminating a concerning safety signal seen with dupilumab therapy.

The efficacy signal in the COPD-like subgroup (late-onset asthma with fixed airflow obstruction) is particularly noteworthy given the limited treatment options for inflammatory COPD. If confirmed in dedicated COPD trials, this could represent a major therapeutic advance for a condition with significant unmet need.

– Rademikibart significantly improved airway function, as measured by FEV₁, within a day and significantly reduced acute exacerbations in patients with inflammation-mediated chronic asthma strongly supporting ongoing Phase 2 acute exacerbation studies in asthma and COPD which are expected to report topline data in 1H26 –

– New preclinical data highlights differentiated structural and molecular dynamics of rademikibart with enhanced interleukin-4 receptor alpha (IL-4Rα) inhibition compared to dupilumab providing a molecular basis for the differentiated efficacy and safety observed with rademikibart presented at this meeting –

SAN DIEGO, May 20, 2025 (GLOBE NEWSWIRE) -- Connect Biopharma Holdings Limited (Nasdaq: CNTB) (Connect Biopharma, Connect or the Company), a clinical-stage biopharmaceutical company focused on transforming acute and chronic care of asthma and chronic obstructive pulmonary disease (COPD), today announced clinical and preclinical data supporting rademikibart, the Company’s next-generation, potentially best-in-class anti-interleukin-4-receptor alpha (IL-4Rα) antibody, which was presented at the American Thoracic Society (ATS) 2025 International Conference, taking place from May 18-21, 2025, in San Francisco.

“We are pleased to share new clinical and preclinical data highlighting rademikibart’s potential as a best-in-class treatment for patients with asthma or COPD experiencing an acute exacerbation,” said Barry Quart, Pharm.D., CEO and Director of Connect Biopharma. “The new analyses from our previously completed Phase 2b study not only demonstrate rademikibart’s rapid onset of action and significant improvement in lung function, but also further differentiate its safety profile, overcoming limitations of existing IL-4Rα inhibitors on the market. Taken together, these data reinforce our confidence in our clinical development plan and provide strong commercial rationale for rademikibart as a potentially superior next-generation IL-4Rα inhibitor.”

Title: Rapid Improvement in Lung Function Observed with Rademikibart in Patients with Moderate-to-Severe Uncontrolled Asthma

• At-home spirometry readings from Connect’s Phase 2b trial of rademikibart for moderate-to-severe uncontrolled asthma were evaluated in a post-hoc analysis to assess rademikibart’s ability to rapidly improve lung function.
• Rademikibart rapidly improved lung function (FEV₁) during the initial week of treatment, and most FEV₁ increase was observed within 24 hours.
• Improvements in self-assessed prebronchodilator FEV₁ were greatest in patients with elevated eosinophil counts (≥300 cells/µL) with or without elevated exhaled nitric oxide (FeNO ≥25 ppb), markers of type 2 inflammation, as compared with the overall population.
• Patients with type 2 inflammatory asthma in this study also showed a significant reduction in acute exacerbations.
• Findings support rademikibart’s potential as an effective therapy for patients with asthma or COPD experiencing an acute exacerbation, providing both fast-acting and sustained improvements in lung function.
  

Title: Efficacy of Rademikibart in COPD-like Patients: Sub-analyses From the Phase 2b Trial in Patients with Moderate-to-Severe Asthma

• Results from the Company’s Phase 2b trial of rademikibart in moderate-to-severe asthma were assessed in a post-hoc analysis to determine rademikibart’s efficacy in subgroup of COPD-like patients, defined as asthma onset after 40 years of age and post−bronchodilator FEV₁/FVC ratio <0.7.
• Rademikibart significantly improved prebronchodilator FEV₁ from first assessment and was sustained through 24 weeks of treatment, with greatest improvements in patients with elevated baseline eosinophil counts (≥150 cells/µL and ≥300 cells/µL).
• These results suggest that rademikibart has the potential to improve outcomes for patients with COPD, particularly in patients with eosinophilic-driven COPD.
  

Title: Effect of Rademikibart on Blood Eosinophil Counts in Patients with Asthma: Is There an IL-4Rα Class Effect?

• In a post-hoc analysis, eosinophil data from the Company’s Phase 2b trial of rademikibart and from the Phase 3 VENTURE and QUEST trials of dupilumab were indirectly compared to determine whether hypereosinophilia is an IL-4Rα inhibitor class effect following published cases of dupilumab-associated hypereosinophilia.
• Rademikibart treatment groups were associated with substantially lower proportions of patients experiencing high post-baseline eosinophil counts than with dupilumab treatment groups. Proportions of patients with high post-baseline eosinophil counts were comparable in the placebo groups, indicating that differences in the active treatment groups are due to drug effect.
• In the rademikibart treatment groups mean eosinophil counts decreased by approximately 30% at Week 24, compared to a mean eosinophil increase between 50% and 120% for dupilumab during 52 weeks of treatment.
• Based on this analysis, the lack of an increase in eosinophils with rademikibart suggests that increased eosinophil counts observed in published data for dupilumab is unlikely to be an IL-4Rα inhibitor class effect, further differentiating rademikibart’s safety profile as a potentially best-in-class IL-4Rα inhibitor.

Title: Optimized Second-generation IL-4Rα Inhibition: Structural and Molecular Dynamics Properties of Rademikibart Fab-IL-4Rα Complex

• Rademikibart is an optimized next-generation human monoclonal antibody targeting IL-4Rα.
• In this study, Connect evaluated the atomic-resolution 3D structures of rademikibart and dupilumab, that may lead to an understanding of the differences in efficacy and safety between the two drugs.
• The x-ray crystal structure of rademikibart Fab-IL-4Rα complex revealed an ~60° rotation of rademikibart on IL-4Rα compared to dupilumab, optimizing interference with the natural IL-4/IL-13 epitope, while dupilumab binds to IL-4Rα through only domain 1, thereby incompletely engaging the natural IL-4/IL-13 epitope on IL-4Rα.
• Compared to dupilumab, molecular dynamics studies showed rademikibart forms a very strong and stable interaction with IL-4Rα, confirmed structurally by lower B-factors (less motion) and more hydrogen bonds (stronger binding) than dupilumab.
• These results further support previously published data showing that rademikibart demonstrated better inhibition of STAT6 intracellular signaling, provided similar potency in prohibiting both IL-4-induced TARC release and IL-4-induced B cell activation and has more than 2-fold higher binding affinity to IL-4Rα compared to dupilumab.
• These data support the underlying molecular and structural rationale for enhanced IL-4Rα inhibition by rademikibart compared to dupilumab.

The poster presentations will be available on Connect’s website under the Presentations and Publications section.

About Connect Biopharma and Rademikibart
Connect Biopharma is a clinical-stage biopharmaceutical company dedicated to transforming care for asthma and COPD. Headquartered in San Diego, California, the company is advancing rademikibart, a next-generation, potentially best-in-class anti-interleukin-4-receptor alpha (IL-4Rα) antibody. With an initial focus on acute exacerbations—an area with significant unmet need—rademikibart has the potential to also drive chronic utilization in asthma and COPD amongst the approximately 1 million asthma patients and 1.3 million COPD patients in the U.S. who experience acute exacerbations annually. In a Phase 2 trial for asthma, rademikibart demonstrated strong efficacy and safety data, with clinically meaningful reductions in exacerbations and rapid, statistically significant improvements in forced expiratory volume in one second (FEV₁), observed within one week—and in most cases, within 24 hours via home spirometry.

For more information visit www.connectbiopharm.com.

Forward-Looking Statements

This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, as amended (the “Act”). Forward-looking statements are statements that are not of historical fact and include, without limitation, statements regarding future events, our future financial condition, results of operations, business strategy and plans, prospective products (as well as their potential to achieve a differentiated, competitive, or favorable benefit or profile or trend, including on safety, tolerability, improvement, maintenance, clinical response, dosing, efficacy and/or convenience), planned or expected product approval applications or approvals, anticipated milestones, expected data readouts and enrollments, research and development plans and costs, potential future partnerships, expectations about existing partnerships, timing and likelihood of success, objectives of management for future operations, future results of anticipated product development efforts, and adequacy of existing cash and potential partnership funding to fund operations and capital expenditure requirements, as well as statements regarding industry trends. These statements are based on management’s current expectations of future events only as of the date of this press release and are inherently subject to a number of risks, uncertainties and assumptions, some of which cannot be predicted or quantified and some of which are beyond our control, including, among other things: the ability of our clinical trials to demonstrate safety and efficacy of our product candidates and other positive results; whether we will need expanded or additional trials in order to obtain regulatory approval for our product candidates; our ability to obtain and maintain regulatory approval of our product candidates; existing regulations and regulatory developments in the U.S., the PRC, Europe and other jurisdictions; the ability of our current cash and investments position to support planned operations; our plans and ability to obtain, maintain, protect and enforce our intellectual property rights and our proprietary technologies, including extensions of existing patent terms where available; our continued reliance on third parties to conduct additional clinical trials of our product candidates, and for the manufacture of our product candidates for preclinical studies and clinical trials; and the degree of market acceptance of our product candidates, if approved, by physicians, patients, healthcare payors and others in the medical community.

Words such as “aim,” “anticipate,” “believe,” “could,” “expect,” “feel,” “goal,” “intend,” “may,” “optimistic,” “plan,” “potential,” “promising,” “will,” and similar expressions are intended to identify forward-looking statements, though not all forward-looking statements necessarily contain these identifying words. The inclusion of forward-looking statements should not be regarded as a representation by Connect Biopharma that any of its expectations, projections or plans will be achieved. Actual results may differ materially due to the risks and uncertainties inherent in our business and other risks described in our filings with the U.S. Securities and Exchange Commission (the “SEC”). Further information regarding these and other risks is included under the heading “Risk Factors” in our annual and periodic reports filed with the SEC. These forward-looking statements should not be taken as forecasts or promises nor should they be taken as implying any indication, assurance or guarantee that the assumptions on which such forward-looking statements have been made are correct or exhaustive or, in the case of the assumptions, fully stated in this presentation. Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Results in early-stage clinical trials may not be indicative of full results or results from later stage or larger scale clinical trials and do not ensure regulatory approval. You are cautioned not to place undue reliance on the scientific data presented or these forward-looking statements, which speak only as of the date of this presentation. Except as required by law, Connect Biopharma undertakes no obligation to publicly update any forward-looking statements, whether because of new information, future events or otherwise. Connect Biopharma claims the protection of the safe harbor for forward-looking statements contained in the Act for all forward-looking statements.

This press release discusses our product candidate, rademikibart, which is under clinical investigation and has not yet been approved for marketing by the U.S. Food and Drug Administration or by any other regulatory agency. No representation is made as to the safety or effectiveness of rademikibart for the uses for which it is being studied. The trademarks included herein are the property of the owners thereof and are used for reference purposes only.

Investor Relations Contact:

Alex Lobo
Precision AQ
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(212) 698-8802

Media Contact:

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Russo Partners, LLC
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FAQ

What are the key advantages of CNTB's rademikibart over dupilumab?

Rademikibart shows faster improvement in lung function (within 24 hours), better safety profile with decreased eosinophil counts, and stronger binding to IL-4Rα due to optimized molecular structure compared to dupilumab.

When will Connect Biopharma (CNTB) release Phase 2 topline data for rademikibart?

Connect Biopharma expects to report topline data from Phase 2 studies in asthma and COPD in the first half of 2026.

How does rademikibart affect eosinophil counts compared to dupilumab?

Rademikibart decreases eosinophil counts by approximately 30% at Week 24, while dupilumab shows an increase between 50-120% during 52 weeks of treatment.

What patient populations showed the best response to rademikibart in clinical trials?

Patients with elevated eosinophil counts (≥300 cells/µL) with or without elevated exhaled nitric oxide showed the greatest improvements in lung function, along with COPD-like patients with elevated baseline eosinophils.

How quickly does rademikibart improve lung function in asthma patients?

Rademikibart demonstrates rapid improvement in lung function (FEV1) during the initial week of treatment, with most improvement observed within 24 hours.