Frunevetmab (Solensia) for Feline OA Pain: RCT Results — Gruen et al. 2021

Bottom line

• Frunevetmab (Solensia), a felinized anti-nerve growth factor (NGF) monoclonal antibody, was evaluated in a randomized, placebo-controlled, parallel-group, double-blind superiority trial (n = 275 client-owned cats) with naturally occurring OA pain; the drug was administered SC at a nominal dose of 1.0 mg/kg on days 0, 28, and 56.¹
• Significant improvement over placebo was demonstrated on the client-specific outcome measures (CSOM) questionnaire at days 28 and 56 (NNT of 9 and standardized effect size of 0.3 at day 56); owner-assessed global treatment response at days 28 and 56; and veterinarian-assessed joint pain at days 56 and 84.¹
• Adverse events did not differ between groups overall; however, skin disorders were significantly more frequent in frunevetmab-treated cats (32/182 cats, 17.6%) versus placebo (8/93 cats, 8.6%), a finding that warrants monitoring at each injection visit.¹
• This is a clinician-facing evidence summary. It is not a dosing protocol; confirm regimen, monitoring and contraindications against current product labeling and a veterinary formulary.

Study at a glance

Parameter	Detail
Study design	Randomized, placebo-controlled, parallel-group, double-blind, superiority
Population	275 client-owned cats, naturally occurring OA pain with mobility impairment
Intervention	Frunevetmab 1.0 mg/kg SC (effective dose range 1.0–2.8 mg/kg), days 0, 28, 56
Control	Matched placebo SC
Primary outcomes	CSOM questionnaire; owner global treatment response; veterinarian-assessed joint pain
Enrolled	182 frunevetmab / 93 placebo

Why this matters: a mechanism distinct from NSAIDs

Frunevetmab targets nerve growth factor (NGF), a neurotrophin elevated in OA joint tissue that sensitizes nociceptors and drives both peripheral and central sensitization.¹ By binding NGF directly, frunevetmab interrupts pain signaling upstream of prostaglandin pathways — providing an analgesic option without the COX-mediated renal or GI effects associated with NSAIDs. This makes it pharmacologically complementary to existing NSAID therapy and potentially valuable in cats where NSAID use is complicated by renal disease or intolerance, though head-to-head trials against NSAIDs in cats have not been published as of the Gruen 2021 data cut.

Evidence summary

Efficacy endpoints

The primary outcome was the CSOM questionnaire, a validated owner-reported tool in which owners identify 3 activities of daily living their cat has difficulty performing and rate ability at each visit.² Frunevetmab achieved statistically significant improvement over placebo on CSOM success rates and total scores at days 28 and 56 (NNT of 9 at day 56, ES of 0.3).¹ Owner-assessed global treatment response — a categorical owner impression of overall treatment effect — was significantly superior to placebo at days 28 and 56.¹ Veterinarian-assessed joint pain (orthopedic examination score) reached significance at days 56 and 84 (ES of 0.18 at day 56).¹

The delayed veterinarian-assessed response relative to the owner-reported response at day 28 is clinically instructive: owner-detected functional improvement often precedes detectable changes on clinical examination, reflecting the limits of point-in-time orthopedic assessment in cats.

Safety signal: skin disorders

Adverse events overall did not significantly differ between groups. However, skin disorders as a collective category occurred significantly more frequently in frunevetmab-treated cats: 32/182 (17.6%) versus 8/93 (8.6%) in placebo.¹ The clinical manifestations and severity were not detailed in the primary publication abstract, but this signal aligns with the known dermatological adverse event profile of anti-NGF antibodies (NGF plays a role in skin homeostasis and wound healing). Post-marketing surveillance data subsequently published identified pruritus, alopecia, dermatitis, and skin ulceration as the most disproportionately reported adverse events in real-world frunevetmab use — consistent with the RCT signal. Clinicians should examine injection sites and skin at each monthly visit and counsel owners on what to report between appointments.

Clinical importance statement

Frunevetmab addresses a critical gap in feline OA pain management: a monthly SC injection that does not require daily owner administration, avoids the hepatic and renal monitoring burden of chronic NSAIDs, and acts through a mechanistically distinct pathway.¹ The NNT of 9 at day 56 on CSOM is in a clinically meaningful range for chronic pain therapeutics.

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References

1. Gruen ME, Myers JAE, Tena JS, Becskei C, Cleaver DM, Lascelles BDX. 2021. Frunevetmab, a felinized anti-nerve growth factor monoclonal antibody, for the treatment of pain from osteoarthritis in cats. J Vet Intern Med 35(6):2752-2762. https://europepmc.org/articles/PMC8692178
2. Gruen ME, Thomson AE, Griffith EH, et al. 2016. A feline-specific anti-nerve growth factor antibody improves mobility in cats with degenerative joint disease-associated pain: a pilot proof of concept study. J Vet Intern Med 30(4):1138-1148. https://europepmc.org/articles/PMC5153962

Changelog

• 2026-06-23: First published.

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For licensed veterinary professionals. Evidence summary, not clinical advice. Voyage is decision support, not a substitute for clinical judgment — always confirm dosing and treatment with current formularies and your own clinical judgment.