Bimzelx Momentum Builds as Rheumatologists Look Beyond TNFs to the Next Wave of axSpA Therapies, According to Spherix Global Insights

Rheumatologists report growing confidence in and use of UCB’s Bimzelx, even as broader unmet needs in axSpA drive interest in emerging agents such as tulisokibart, sonelokimab, and filgotinib.

Exton, PA, Aug. 19, 2026 (GLOBE NEWSWIRE) -- Rheumatologist preferences in axial spondyloarthritis (axSpA) are moving decisively beyond TNF inhibitors, even as payer requirements, clinical familiarity, and strong biosimilar coverage continue to keep the class firmly established as the default first-line advanced therapy for ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA).

According to Spherix Global Insights’ latest Market Dynamix™: Ankylosing Spondylitis & Non-Radiographic Axial Spondyloarthritis (US) 2026 study, fewer than six in ten rheumatologists are satisfied with current treatment options, fueling interest in newer brands such as UCB’s Bimzelx® (bimekizumab) and emerging pipeline mechanisms.

IL-17 Preference Continues to Climb as TNF-First Dominance Erodes

Rheumatologists’ preferred mechanism has moved from approximately two-thirds TNF inhibitor and one-quarter IL-17 inhibitor in 2023 to a near-even split by mid-2026, with the shift even more pronounced in nr-axSpA. However, TNF inhibitors still account for the large majority of first-line advanced therapy prescriptions, supported by long-standing clinical experience and stronger payer access, while IL-17 and JAK inhibitors gain meaningful ground in later lines.

Among rheumatologists who changed their axSpA treatment approach during the past year, the most common shift was greater use of IL-17 inhibitors and Bimzelx specifically. A majority expect to increase Bimzelx use over the next six months, supported by positive three-year EULAR data, confidence in its dual IL-17A/F inhibition, and a growing share of recent IL-17 prescriptions, bringing Bimzelx closer to established agents Cosentyx® (secukinumab, Novartis) and Taltz® (ixekizumab, Eli Lilly).

Access Friction Tempers Clinical Enthusiasm

Payer influence remains substantial, with more than seven in ten rheumatologists reporting that coverage policies strongly shape biologic or JAK inhibitor selection. Bimzelx currently faces the greatest likelihood of an initial prior authorization denial, largely because of step therapy, while strong support for adalimumab and infliximab biosimilars helps preserve TNF inhibitors’ first-line dominance.

Unmet Need Sustains Interest in New Mechanisms and Oral Options

Rheumatologists most frequently identify the need for more effective and safer therapies with genuinely novel mechanisms of action as the greatest remaining gap in axSpA care. A strong preference for oral administration follows closely behind. These unmet needs are especially pronounced among difficult-to-manage (D2M) axSpA patients, who represent approximately one in five axSpA patients by physician estimate. These patients are typically characterized by cycling through multiple biologic or targeted synthetic mechanisms without achieving adequate disease control and are widely expected to drive treatment innovation in the market over the next five years.

Tulisokibart Tops the Physician Wish List as Sonelokimab Leads in Overall Interest

When required to select the single pipeline agent they would most like to see approved for axSpA, rheumatologists most frequently chose Merck’s tulisokibart, an investigational anti-TL1A monoclonal antibody. The finding is particularly notable because physician familiarity with tulisokibart trails that of other pipeline candidates, with interest driven primarily by its genuinely novel mechanism of action.

MoonLake’s sonelokimab, a dual IL-17A/F-targeting nanobody, generated the highest overall interest score among the pipeline agents evaluated. Physicians point to its strong Phase 2 efficacy data and a mechanism they already understand, and trust based on experience with Bimzelx’s dual IL-17A/F profile. However, sonelokimab ranked behind tulisokibart when physicians were asked to select only one agent for approval. The distinction suggests that, when forced to prioritize, rheumatologists may place greater value on mechanistic novelty than on another promising entrant within an increasingly familiar class. Sonelokimab will also need to demonstrate meaningful differentiation from Bimzelx as it advances.

Oral options also remain attractive, with Alfasigma’s filgotinib (Jyseleca®) generating interest based on its once-daily administration and positive Phase 3 results, though rheumatologists will expect clear differentiation from AbbVie’s Rinvoq® (upadacitinib).

As additional mechanisms advance through development, the axSpA market appears positioned to diversify beyond the current TNF, IL-17, and JAK dynamic. Novel targets such as TL1A and convenient oral options could reshape treatment decisions, with difficult-to-manage patients representing a particularly important population for future innovation given their inadequate disease control with existing therapies.

“The changing axSpA landscape shows that rheumatologists are increasingly willing to move beyond established treatment paradigms when they see meaningful clinical differentiation,” said Ryan Rex, Senior Director at Spherix Global Insights. “The next winners in axSpA will need to offer clear advantages in efficacy, safety, convenience, or the ability to address patients who remain difficult to manage with today’s therapies.”

Findings are drawn from Spherix Global Insights’ Market Dynamix™: Ankylosing Spondylitis & Non-Radiographic Axial Spondyloarthritis (US) 2026 study, a quantitative survey of 103 U.S. rheumatologists fielded between June 11 and June 23, 2026.

About Market Dynamix ™

Market Dynamix™ is an independent, data-driven service focused on understanding the evolving dynamics of specialty markets poised for disruption. Leveraging quantitative and qualitative research, the service evaluates current treatment approaches, unmet needs, and likely impact of pipeline agents over a three-to-five-year horizon.

About Spherix Global Insights

Spherix Global Insights is a leading independent provider of market intelligence and advisory services for specialty pharmaceutical and biotech markets. By combining physician, patient, and payer perspectives into a single integrated view, Spherix helps brand teams, market access stakeholders, and investors understand how a specialty market actually behaves, not how any one stakeholder describes it. The firm operates eight dedicated therapeutic franchises: Central Nervous System, Dermatology, Gastroenterology, Hematology, Nephrology, Oncology, Ophthalmology, and Rheumatology, alongside a fully dedicated Market Access team. Each franchise is led by hyper-focused analysts and researchers who track these specialty areas full-time, drawing on independently curated communities of vetted practicing specialists, KOLs, patients recruited through treating physicians and advocacy partners, and medical and pharmacy directors at commercial and government payers. Spherix delivers quarterly trending, launch tracking, chart audits, KOL synthesis, patient experience research, and payer and market access intelligence that support confident, strategic decision-making across the pharma lifecycle. Trusted by 19 of the top 20 pharmaceutical and biotech organizations, Spherix has been a go-to resource for more than a decade for leading brands, market access stakeholders, industry media outlets, financial analysts, professional organizations, and patient advocacy groups seeking an unbiased, holistic view of specialty markets.

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Lynn Price
Spherix Global Insights
484-879-4284
lynn.price@spherixglobalinights.com