BI Bets on Biomarker-Only Equine VLP Data: Clinical Proof Still Missing

Boehringer Ingelheim Acquires Evax AG for Equine Health

Boehringer Ingelheim announced the acquisition of Evax AG, a Swiss biotech company focused on equine health. Evax specializes in developing therapeutic vaccines using virus-like particles to address significant unmet needs in horses, particularly for allergic skin diseases. This strategic acquisition aims to provide horse owners with an innovative therapeutic option that targets the underlying cause of these conditions, potentially offering longer-lasting relief and improved treatment outcomes compared to existing temporary solutions. The terms of the transaction were not disclosed.

• Boehringer Ingelheim's acquisition of Evax AG strategically expands its equine health pipeline, reinforcing its commitment to breakthrough innovation in preventive and therapeutic animal health. This move aligns with the company's broader strategy, building on previous investments in therapeutic vaccines, such as the 2024 acquisition of Saiba Animal Health.
• Evax AG's core innovation lies in its therapeutic vaccines, which incorporate virus-like particles designed to induce the horse’s immune system to produce neutralizing antibodies. This novel approach aims to treat the underlying cause of allergic skin diseases, representing a significant advancement in animal health technology.
• The acquisition directly addresses a critical unmet medical need in equine health, as allergic skin diseases are prevalent, challenging to manage, and significantly impact horse welfare. Current treatment options often provide only temporary relief or carry safety concerns, making Evax's potential for a long-duration, cause-targeting therapy highly impactful for horse owners.

Addressing the Unmet Need in Equine Allergic Skin Diseases

Current treatment approaches for allergic skin diseases face a complex interplay of safety concerns, adherence barriers, and individualization challenges that collectively limit therapeutic outcomes. Despite an expanding pharmacological armamentarium — from topical agents to advanced biologics and small molecules — significant gaps remain in optimizing care across patient populations.

• Topical corticosteroid (TCS) phobia and adherence failure: TCS phobia is highly prevalent, with 98% of participants in one study expressing some degree of concern (mean global TOPICOP score: 32.7 ± 6.7%). This phenomenon is more pronounced among parents of young children and is significantly associated with high education levels, severe disease, prior adverse effects, and preference for non-steroidal alternatives — collectively driving poor adherence and therapeutic failure.

• Pediatric safety risks with long-term TCS use: Children face disproportionate systemic exposure due to higher surface area-to-volume ratios and slower drug metabolism. A meta-analysis of 522 pediatric participants identified HPA axis suppression in 3.8% of cases overall, rising to 6.6% with high-potency TCS — underscoring the risks of long-term monotherapy in this population.

• Insufficient long-term safety data for TCS: Systematic reviews have highlighted a notable absence of robust safety data for mid- to high-potency TCS in pediatric atopic dermatitis. Discontinuation due to adverse effects was addressed in only 2 trials, and systemic or cutaneous adverse events were largely unreported across studies.

• Regulatory and perception barriers to topical calcineurin inhibitors (TCIs): Since 2006, TCIs have carried a Boxed Warning based on a theoretical malignancy risk (skin cancer and lymphoma), constraining their use as standard maintenance therapy. Parental concerns over long-term safety further limit acceptance, particularly in pediatric populations.

• Black-box warnings limiting JAK inhibitor uptake: Despite high efficacy in atopic dermatitis and psoriatic arthritis, oral JAK inhibitors (abrocitinib, upadacitinib, baricitinib) carry FDA black-box warnings for major adverse cardiovascular events, venous thromboembolism, malignancy, and mortality — restricting use in at-risk patient subgroups relative to approved biologics.

• Biologic non-response and the need for endotype-guided selection: While dupilumab has transformed atopic dermatitis management, it does not achieve adequate response in all patients. Therapeutic success with biologics is contingent on the patient's pheno-endotype, and the lack of routine immunologic profiling makes individualized biologic selection challenging in clinical practice.

• Access, affordability, and individualization complexity: Optimal therapy selection requires balancing multiple clinical variables — including age, pregnancy status, comorbidities, infection or thromboembolic risk, and history of adverse effects — alongside patient-centered factors such as dosing frequency, route of administration, and willingness to self-inject. Access and affordability further constrain real-world implementation of newer agents.

Evax's VLP Technology: A Novel Approach for Equine Allergies

Recent research into allergic skin diseases — encompassing atopic dermatitis, chronic urticaria, and related conditions — has yielded a rich landscape of emerging therapeutic targets spanning epithelial signaling, cytokine pathways, and intracellular kinase cascades. Epithelial-derived alarmins, particularly thymic stromal lymphopoietin (TSLP), IL-33, and IL-25, have garnered significant attention as upstream drivers of allergic inflammation. IL-33, for instance, plays a critical role in early cutaneous inflammation, with selective loss of epithelial IL-33 expression demonstrably attenuating disease severity. Monoclonal antibodies directed against these alarm factors are already entering clinical use, reinforcing their translational relevance. Alongside this, the IL-4/IL-13 axis remains a focal point: AK120, a humanized IgG4 monoclonal antibody targeting the shared IL-4 receptor alpha (IL-4Rα) subunit, has demonstrated an acceptable safety profile and preliminary efficacy in atopic dermatitis subjects, while therapeutic strategies for chronic spontaneous urticaria continue to explore IgE, IL-4/IL-13, and IL-5 pathway inhibition collectively.

The JAK/STAT signaling pathway represents another well-validated and expanding target class. JAK inhibitors — including abrocitinib, ruxolitinib, and upadacitinib — are now FDA-approved for atopic dermatitis, with their mechanism rooted in disrupting JAK1/3-mediated signaling that underpins broad inflammatory and autoimmune pathology. Concurrently, an expanding pipeline of small-molecule therapies targeting JAK inhibitors and Bruton's tyrosine kinase (BTK) is being developed for chronic urticaria, reflecting growing interest in intracellular signaling nodes as precision intervention points.

At the intersection of neuroimmunology and mast cell biology, several novel targets are emerging. MRGPRX2 (Mas-related G protein-coupled receptor X2), a mast cell receptor implicated in non-IgE-mediated degranulation via substance P, has been identified as a promising — though translationally challenging — target relevant to urticaria, atopic dermatitis, rosacea, and allergic rhinitis. IL-31RA antagonism, exemplified by nemolizumab, has demonstrated clinical efficacy by interrupting pruritogenic signaling from mast cell-derived mediators acting on neuronal receptors. Additional neuroimmune targets under investigation include TRPV1/TRPA1 transient receptor potential channels, protease-activated receptors PAR-1/2 sensitized by mast cell-derived tryptase, and GPR15L — a candidate pruritogen upregulated in both psoriasis and atopic dermatitis that drives mast cell degranulation via MRGPRX2 stimulation. The P2X3 receptor has also been proposed as a neurogenic itch target in atopic dermatitis, though direct clinical validation remains limited at this stage.

Reshaping the Equine Allergic Skin Disease Treatment Landscape

The treatment landscape for allergic skin diseases has undergone substantial transformation over the past five years, driven by the emergence of targeted systemic therapies that address the mechanistic limitations of conventional approaches. In chronic spontaneous urticaria (CSU), standard-of-care antihistamines frequently fail to achieve adequate symptom control, and while omalizumab — a monoclonal antibody targeting IgE — represents the established next-line option, a meaningful subset of patients remains refractory. This gap has catalyzed interest in Bruton's tyrosine kinase (BTK) inhibition as an IgE-independent mechanism of mast cell suppression. Remibrutinib, an oral selective BTK inhibitor, has demonstrated compelling efficacy in Phase II and III trials, with pooled RCT analyses showing a significant reduction in Urticaria Activity Score at Week 12 versus placebo (MD −7.81; 95% CI: −10.29 to −5.33), alongside meaningful improvements in both itch severity (MD −2.94; 95% CI: −3.73 to −2.15) and hive severity scores (MD −4.05; 95% CI: −4.98 to −3.12). The REMIX-1 and REMIX-2 trials further demonstrated markedly superior disease control rates (UAS7 ≤6) as early as Week 2 (RR 6.81; 95% CI: 3.45 to 13.42), with an adverse event profile broadly comparable to placebo, notable exceptions being elevated rates of nasopharyngitis, upper respiratory tract infections, and petechiae.

In moderate-to-severe atopic dermatitis (AD), the therapeutic armamentarium has expanded considerably across both oral and biologic modalities. JAK inhibitors — targeting the JAK-STAT signaling axis to attenuate proinflammatory cytokine production — have been evaluated across multiple Phase 2 and 3 trials in both oral and topical formulations. Oral agents carry a recognized adverse event profile including nausea, upper respiratory tract infection, herpes zoster reactivation, acne, and laboratory abnormalities such as elevated creatine phosphokinase and reduced platelet counts, occurring at 2–5% frequency; topical formulations have not been associated with systemic effects. A network meta-analysis encompassing 13 placebo-controlled trials, 7,105 patients, and 6 targeted therapies identified upadacitinib 30 mg as the most efficacious agent across all primary endpoints at Weeks 12–16, followed by abrocitinib 200 mg, upadacitinib 15 mg, dupilumab 300 mg, and lebrikizumab 250 mg or abrocitinib 100 mg. Notably, upadacitinib also demonstrated utility in patients who developed atopic keratoconjunctivitis during dupilumab therapy, suggesting its value as a rescue or alternative option in AD with ocular involvement.

Among biologics, head-to-head and registry data have begun to differentiate agents within the IL-13/IL-4 inhibitor class. At Week 16, dupilumab every two weeks plus topical corticosteroids showed a statistically significant advantage over lebrikizumab plus topical corticosteroids in achieving EASI-75 (OR 2.4; 95% CI: 1.1–5.1) and a ≥4-point improvement in Peak Pruritus Numeric Rating Scale (OR 2.7; 95% CI: 1.2–6.0). Tralokinumab has introduced response-guided dosing flexibility, with approved maintenance regimens of both Q2W and Q4W dosing; trial data indicate that patients achieving stable IGA 0/1 and worst daily pruritus NRS <3 between Weeks 12–16 maintained comparable response rates at Week 52 regardless of whether dosing was extended (72.0% on Q2W vs. 72.2% on Q4W). Collectively, these advances reflect a paradigm shift from broad immunosuppression toward mechanism-specific, response-adapted therapy across allergic skin disease categories.

Boehringer Ingelheim's Leap into Equine Immunotherapy

Boehringer Ingelheim's recent acquisition of Evax AG signals a strategic pivot towards advanced immunotherapeutic solutions within the animal health landscape, particularly for equine medicine. This move is poised to address a significant unmet need in horses suffering from Insect Bite Hypersensitivity (IBH), a common and debilitating allergic dermatitis. Historically, managing IBH has relied on symptomatic treatments, offering temporary relief without tackling the root cause. Evax's innovative approach, centered on virus-like particle (VLP)-based therapeutic vaccines, represents a paradigm shift.

These vaccines are designed to induce an active immune response against key self-proteins, such as interleukin-31 (IL-31) and interleukin-5 (IL-5), which are central to the pathology of allergic pruritus and eosinophilic inflammation in IBH. Clinical studies have demonstrated that vaccination against eIL-31 can alleviate clinical scores, while eIL-5 vaccination significantly reduces eosinophil counts and, over time, basophil counts. This targeted intervention offers the promise of longer-lasting relief and improved outcomes by modifying the disease's underlying immunological mechanisms.

For Boehringer Ingelheim, this acquisition not only strengthens its animal health portfolio but also establishes it as a leader in cutting-edge veterinary immunotherapy. The VLP platform itself holds broader potential, validating active vaccination against self-proteins as a viable therapeutic strategy across various species and conditions. However, the path forward is not without considerations. The long-term durability of the immune response and the potential need for repeated vaccinations will be crucial for sustained efficacy. Furthermore, while initial safety profiles are encouraging, continuous monitoring for any unforeseen immune-mediated adverse events from targeting self-proteins is essential. The intricate nature of allergic responses also means that a single-target approach, while effective, may not fully resolve all aspects of the disease for every animal, highlighting the ongoing need for comprehensive management strategies.