Merck Animal Health achieved a significant regulatory milestone with the European Medicines Agency's Committee for Veterinary Medicinal Products (CVMP) issuing a positive opinion for NUMELVI™ (atinvicitinib) Tablets for Dogs on June 12, 2025. Upon full approval by the European Commission, NUMELVI will become the first and only second-generation Janus kinase (JAK) inhibitor indicated for treating pruritus associated with allergic dermatitis, including atopic dermatitis, and clinical manifestations of atopic dermatitis in dogs.
Novel Mechanism and Superior Selectivity
NUMELVI represents a breakthrough in veterinary dermatology through its highly selective mechanism of action. The drug inhibits JAK1-dependent cytokines involved in itch and inflammation associated with allergic and atopic dermatitis while demonstrating at least 10-fold greater selectivity for JAK1 compared to other JAK family members (JAK2, JAK3, and TYK2). This selectivity profile minimizes interference with cytokines involved in hematopoiesis and immune functions dependent on other JAKs, resulting in a compelling safety profile with proven efficacy in dogs and puppies.
The once-daily treatment regimen delivers clinical effectiveness after the first dose, offering veterinarians and pet owners a convenient therapeutic option. Notably, NUMELVI will be the only JAK inhibitor approved for use in dogs as young as six months of age, expanding treatment options for younger animals.
Addressing Significant Unmet Medical Need
The positive opinion addresses a substantial clinical need in veterinary medicine. Itch affects more than 20 percent of dogs in general veterinary practice and ranks among the most frequent reasons for veterinary visits. As allergic dermatitis progresses, quality of life in dogs declines significantly, and the relationship between pets and their owners can be strained due to emotional distress, sleep interruptions, routine disruptions, increased expenses, and time lost managing treatment and veterinary follow-up care.
"Merck Animal Health has been committed to bringing innovation to our customers aimed at rapidly controlling and treating a common condition that causes distress for so many pets and pet owners," said Rick DeLuca, executive vice president and president, Merck Animal Health. "With today's positive opinion for NUMELVI, we are one step closer to making this novel, highly selective JAK inhibitor available."
Safety Profile and Vaccination Compatibility
Clinical studies demonstrate that NUMELVI maintains an excellent safety profile while preserving immune function. Treatment with NUMELVI showed no impact on immune response to vaccination, a critical consideration for maintaining comprehensive veterinary care protocols. A vaccine response study confirmed that NUMELVI does not affect the immune response to core vaccinations, allowing veterinarians to maintain standard vaccination schedules without concern.
"NUMELVI not only offers a once-daily dosing regimen but also features a distinctive safety profile that permits its use in dogs as young as six months," said Holger Lehmann, DVM, PhD, vice president and global head of research and development for pharmaceuticals at Merck Animal Health. "Additionally, a vaccine response study has shown that NUMELVI does not affect the immune response to core vaccinations."
Regulatory Timeline and Market Impact
Based on the CVMP's positive recommendation, the European Commission is expected to issue a marketing authorization decision for the European Union during the third quarter of 2025. This timeline positions NUMELVI to address the challenges veterinarians face in managing dogs with allergic dermatitis, where diagnosis and treatment require significant time investment and regular progress monitoring.
The approval would establish NUMELVI as a first-line treatment option, offering veterinarians a novel therapeutic approach for a condition that significantly impacts both animal welfare and the human-animal bond. The drug's unique positioning as the only second-generation JAK inhibitor in veterinary dermatology represents a significant advancement in addressing this common yet challenging condition.
