In intestinal Behçet’s disease, why is anti‑TNF therapy preferred over upadacitinib beyond the lack of trial data—are there specific pathogenesis reasons?

Anti-TNF Therapy is Preferred Over Upadacitinib in Intestinal Behçet's Disease

Anti-TNF agents (infliximab and adalimumab) should be the first-line advanced therapy for intestinal Behçet's disease, with upadacitinib reserved for anti-TNF refractory cases. This preference is driven by both robust clinical evidence and specific pathogenesis considerations unique to Behçet's disease.

Pathogenesis-Based Rationale

TNF-α's Central Role in Behçet's Disease Pathophysiology

The preference for anti-TNF therapy is rooted in the fundamental pathophysiology of Behçet's disease. TNF-α plays a uniquely central role in driving the vasculitic and inflammatory cascade specific to Behçet's disease 1. Unlike inflammatory bowel disease where multiple cytokine pathways contribute relatively equally, Behçet's disease demonstrates TNF-α-driven vascular inflammation as a primary pathogenic mechanism. This explains why anti-TNF agents show particularly robust efficacy across all Behçet's manifestations—mucocutaneous (96.3%), ocular (88%), gastrointestinal (77.8%), and central nervous system (92.3%) involvement 2.

JAK-STAT Pathway: Secondary Rather Than Primary

While JAK-STAT pathway activation has been demonstrated in Behçet's disease (particularly JAK1 and STAT3 phosphorylation in intestinal specimens) 3, this appears to be a downstream consequence of TNF-α signaling rather than a primary driver. The mechanistic data showing JAK-STAT hyperactivation in occluded submucosal vessels suggests this pathway amplifies inflammation initiated by TNF-α 3. This hierarchical relationship explains why JAK inhibitors like upadacitinib work in anti-TNF refractory cases but may not address the fundamental vascular pathology as directly as TNF blockade.

Clinical Evidence Supporting Anti-TNF Priority

Established Efficacy and Safety Profile

The evidence base for anti-TNF therapy in intestinal Behçet's disease is substantially more robust:

• Meta-analysis of 514 patients demonstrated 73.7% achieved clinical symptomatic improvement at 48-54 weeks, with 60.9% achieving sustained mucosal healing at 24-52 weeks 4
• Multicenter study of 124 patients showed 77.8% response rate in gastrointestinal manifestations with acceptable safety profile (28% adverse events, 13% serious adverse events) 2
• Long-term data spanning over a decade with predictable safety profiles 5

Limited Upadacitinib Experience

In contrast, upadacitinib evidence in intestinal Behçet's disease consists primarily of:

• Individual case reports showing efficacy only after anti-TNF failure 6, 3
• No systematic trials or large cohort studies
• Uncertain long-term safety profile in this specific population

Safety Considerations Specific to Behçet's Disease

Vascular Complications and Thrombosis Risk

Behçet's disease carries inherent thrombotic risk due to its vasculitic nature, making the FDA black box warnings for upadacitinib particularly concerning 7. The drug label specifically warns about:

• Increased risk of thrombosis (venous thromboembolism)
• Major adverse cardiovascular events (MACE)
• Mortality risk in higher-risk patients

These risks are especially problematic in Behçet's disease patients who already have elevated baseline thrombotic risk from their underlying vasculitis. Anti-TNF agents do not carry these specific thrombotic warnings and have demonstrated cardiovascular safety in long-term use 2.

Infection Risk Profile

While both drug classes increase infection risk, the pattern differs:

• Anti-TNF agents: Well-characterized infection profile with established screening and monitoring protocols for tuberculosis and opportunistic infections 2
• Upadacitinib: Broader immunosuppression affecting multiple cytokine pathways, with emerging concerns about herpes zoster, serious infections (4.6-8.2 per 100 patient-years), and opportunistic infections 7

In Behçet's disease patients who often require combination immunosuppression, the more predictable anti-TNF infection profile is advantageous.

Clinical Algorithm for Therapy Selection

First-Line Advanced Therapy

1. Initiate anti-TNF therapy (infliximab or adalimumab) for moderate-to-severe intestinal Behçet's disease failing conventional therapy 1
2. Consider combination with azathioprine or other immunosuppressants based on disease severity
3. Monitor for clinical response at 8-12 weeks and mucosal healing at 24-52 weeks

Second-Line Considerations

Upadacitinib should be considered only when:

• Primary non-response to anti-TNF therapy (lack of improvement after 12-14 weeks)
• Secondary loss of response to anti-TNF despite dose optimization
• Intolerance to anti-TNF agents
• AND patient has low cardiovascular/thrombotic risk profile

Dosing Strategy for Upadacitinib (If Used)

Based on case report evidence 3:

• Induction: 45 mg daily
• Maintenance: 30 mg daily (dose reduction to 15 mg led to relapse)
• Monitor closely for thrombotic events, infections, and cardiovascular complications

Key Pitfalls to Avoid

1. Do not use upadacitinib as first-line therapy simply because it's oral and convenient—the pathophysiology and safety profile don't support this approach in Behçet's disease
2. Do not underestimate thrombotic risk when considering upadacitinib in Behçet's patients with vascular involvement
3. Do not assume IBD data translates directly to Behçet's disease—while upadacitinib shows superiority in ulcerative colitis 8, 9, the distinct vasculitic pathophysiology of Behçet's disease makes TNF-α blockade more mechanistically appropriate
4. Do not use inadequate upadacitinib dosing if prescribed—maintenance requires 30 mg daily, not 15 mg 3

Why This Differs from IBD Guidelines

The 2024-2025 IBD guidelines show upadacitinib as highly effective, even superior to some biologics in ulcerative colitis 10, 8. However, intestinal Behçet's disease is fundamentally different from IBD:

• Vasculitic vs. mucosal inflammation: Behçet's involves transmural vascular inflammation, not primarily epithelial barrier dysfunction
• TNF-α centrality: More dominant in Behçet's pathogenesis than in IBD's multi-pathway inflammation
• Thrombotic baseline risk: Higher in Behçet's disease, making JAK inhibitor risks more concerning
• Evidence base: Robust for anti-TNF in Behçet's vs. only case reports for upadacitinib

The pathogenesis-driven approach, combined with superior evidence and safety profile, makes anti-TNF therapy the clear first choice for intestinal Behçet's disease, with upadacitinib serving as a valuable rescue option for refractory cases.