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Tezepelumab — TSLP Inhibitor for Severe Uncontrolled Asthma

First and only biologic targeting upstream epithelial cytokine TSLP (Thymic Stromal Lymphopoietin) approved for severe asthma regardless of phenotype (eosinophilic, allergic, or T2-low); 210 mg subcutaneous every 4 weeks; reduces annualized asthma exacerbation rate by 56–71 percent across all biomarker subgroups; effective in patients with low eosinophil counts (<300 cells/μL) and low T2 disease where other biologics (anti-IgE omalizumab, anti-IL-5 mepolizumab/reslizumab, anti-IL-5R benralizumab, anti-IL-4Rα dupilumab) provide limited benefit; transformative addition to severe asthma armamentarium.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

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What is Tezepelumab — TSLP Inhibitor for Severe Uncontrolled Asthma?

Tezepelumab (Tezspire, AMG-157/MEDI-9929) is a fully human monoclonal antibody (IgG2λ) developed by AstraZeneca and Amgen, targeting Thymic Stromal Lymphopoietin (TSLP), an epithelial-derived cytokine released from airway epithelial cells in response to multiple stimuli (allergens, viruses, bacteria, fungi, air pollutants, mechanical stress, smoke). TSLP acts at the apex of the asthma inflammatory cascade by activating multiple immune cell types: dendritic cells, innate lymphoid cells type 2 (ILC2s), Th2 cells, mast cells, basophils, eosinophils, and B cells, thereby driving both T2-high (IL-4, IL-5, IL-13 — eosinophilic, allergic) and non-T2 (neutrophilic, paucigranulocytic) asthma inflammation pathways.

FDA approved December 2021 in the United States and EMA approved September 2022 in the European Union as add-on maintenance treatment for severe asthma in adult and adolescent patients ≥12 years old. Approved across all phenotypes — first biologic without biomarker requirement (no eosinophil count threshold, no FeNO threshold, no IgE threshold required). Dosing: 210 mg subcutaneous every 4 weeks, administered as single-dose pre-filled syringe or autoinjector pen, can be self-administered after appropriate training, in thigh or abdomen.

Mechanism: TSLP binds heterodimeric receptor (TSLPR/CRLF2 plus IL-7Rα chain) on dendritic cells, ILC2s, T cells, mast cells; downstream signaling (JAK1/JAK2-STAT5) drives Th2 differentiation, ILC2 activation, eosinophilic infiltration, IgE production, and airway inflammation. Tezepelumab binds free TSLP with high affinity, preventing TSLP-receptor interaction and downstream cytokine cascade activation. Unlike biologics targeting individual downstream cytokines (IL-4, IL-5, IL-13) or IgE, tezepelumab interrupts upstream master cytokine and provides broader anti-inflammatory effect across asthma endotypes.

Pivotal clinical trials: PATHWAY phase 2b trial established efficacy and dose; NAVIGATOR phase 3 trial (n=1,061, ages 12–80, severe uncontrolled asthma despite medium-high dose ICS-LABA) — primary endpoint annualized asthma exacerbation rate (AAER) over 52 weeks: 210 mg every 4 weeks reduced AAER by 56 percent versus placebo (0.93 vs 2.10 per year, p<0.001); benefit consistent across all subgroups including blood eosinophils <300 cells/μL (41 percent reduction), <150 cells/μL (39 percent reduction), and even biomarker-low patients (low eos AND low FeNO — 39 percent reduction in this previously intractable group); also improved pre-bronchodilator FEV1 (+0.13 L), asthma control questionnaire (ACQ-6), asthma quality of life questionnaire (AQLQ), reduced number of severe exacerbations requiring hospitalization or emergency visit. SOURCE phase 3 trial in oral corticosteroid-dependent severe asthma: significant 50 percent OCS reduction in 76 percent of patients vs 51 percent of placebo. DESTINATION extension trial confirmed long-term efficacy and safety up to 2 years.

Symptoms

Severe asthma uncontrolled despite high-dose ICS-LABA
Frequent severe exacerbations (≥2 per year requiring oral corticosteroids)
Oral corticosteroid dependence with significant cumulative steroid exposure
Low blood eosinophils (<300 cells/μL) where other biologics may have limited benefit
T2-low or non-T2 inflammation phenotype
Failure or partial response to other biologics (omalizumab, mepolizumab, reslizumab, benralizumab, dupilumab)
Overlapping asthma phenotypes (mixed Th2-non-Th2)
Persistent symptoms despite optimal controller therapy
Need for OCS-sparing strategy
Frequent emergency visits or hospitalizations for asthma

Risk Factors

Severe asthma with frequent exacerbations and poor control
Genetic predisposition (asthma family history, atopic comorbidities)
Environmental triggers (allergens, viruses, pollutants, smoke)
Comorbidities (obesity, GERD, allergic rhinitis, CRSwNP, sleep apnea)
Failure of conventional asthma therapy (ICS, LABA, LAMA, leukotriene modifiers)
Smoking history (active or passive)
Occupational exposure to airborne irritants
Pregnancy planning (limited data on tezepelumab in pregnancy)
Helminth endemic area (precaution due to mechanism affecting Th2 immunity)
Live vaccine plans (although not strictly contraindicated, timing considered)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Severe uncontrolled asthma despite optimal step 4-5 GINA therapy
  • Frequent exacerbations requiring oral corticosteroids despite controller therapy
  • Need for assessment of biologic candidacy in severe asthma
  • Failure of previous biologic with persistent disease
  • Low T2 biomarker patient with severe disease where other biologics may not apply
  • Need for OCS-sparing strategy due to corticosteroid side effects
  • Comprehensive severe asthma center evaluation
  • Asthma-CRSwNP-eosinophilic comorbid disease (consider dupilumab vs tezepelumab)
  • Worsening asthma control despite tezepelumab — adherence and trigger evaluation
  • Pregnancy planning while on tezepelumab

Treatment Methods

01
Diagnostic workup confirming severe asthma: detailed history (asthma diagnosis confirmation, GINA control assessment, exacerbation frequency over 12 months, OCS use and cumulative dose, controller therapy adherence, trigger profile), comprehensive physical examination, spirometry with bronchodilator reversibility (FEV1, FEV1/FVC, peak flow variability), measurement of FeNO (T2 inflammation marker, useful but not required for tezepelumab), blood eosinophil count (recent — within 1–6 months), serum total IgE (for omalizumab eligibility comparison), specific IgE or skin prick testing for aeroallergens, sputum induction if available (eosinophilic vs neutrophilic), chest CT to exclude alternative diagnoses (bronchiectasis, ABPA, vocal cord dysfunction, EGPA), assessment of comorbidities (GERD, sinusitis with polyps, sleep apnea, obesity, smoking)
02
Assessment of severe asthma criteria per ERS/ATS 2014 definition: requires high-dose ICS plus LABA (or other controller) for ≥6 months for control, AND uncontrolled despite this therapy (poor control on ACT/ACQ, ≥2 exacerbations per year requiring OCS, severe exacerbation requiring hospitalization or ICU, FEV1 <80 percent predicted)
03
Biologic selection algorithm: (1) Allergic asthma with elevated IgE 30–700 IU/mL, perennial allergen sensitization → omalizumab; (2) Eosinophilic asthma with blood eos ≥300 cells/μL → mepolizumab, reslizumab, or benralizumab; (3) Eosinophilic asthma with elevated FeNO and blood eos ≥150 cells/μL or specific biomarker pattern, especially with comorbid CRSwNP or atopic dermatitis → dupilumab; (4) T2-low or low eosinophil severe asthma, patients failing other biologics, broad phenotype → tezepelumab (only biologic effective regardless of biomarkers); often more than one option appropriate — patient preference, comorbidities, dosing frequency considered
04
Pre-treatment assessment: complete asthma optimization (controller therapy adherence and inhaler technique, trigger avoidance, comorbidity management), confirmation of severe asthma criteria, baseline biomarkers documentation, vaccination status update (avoid live vaccines starting), pregnancy testing in women of childbearing potential, helminth screening if endemic exposure, baseline pulmonary function and asthma control questionnaire scores
05
Initiation: 210 mg subcutaneous every 4 weeks; first administration in clinic for monitoring, then self-administration after training; pre-filled syringe or autoinjector pen options; rotate injection sites (thigh, abdomen, upper arm if administered by another); refrigerated storage (allow to reach room temperature 60 minutes before injection)
06
Monitoring efficacy: assess asthma control at 3 months and 6 months (ACT, ACQ-6 questionnaires), spirometry, exacerbation frequency, OCS dose tapering attempts; document response in registry; if good response, continue indefinitely; if poor response (no improvement at 6 months), consider switching biologic or adding therapy; expect benefit even in low-T2 patients
07
Monitoring safety: standard biologic safety monitoring; common adverse events — pharyngitis (4 percent), arthralgia (3.8 percent), back pain (3.7 percent), injection site reactions; rare anaphylaxis (no fatal cases reported); no significant infection signal (similar to placebo in trials); no signal for malignancy, MACE; helminth infection precaution (pre-treatment screening recommended if endemic exposure; consider treatment of confirmed helminth before biologic)
08
Pregnancy: limited human data; nonclinical studies do not suggest direct or indirect harmful effects; risk-benefit discussion with patient; severe uncontrolled asthma during pregnancy is high-risk; tezepelumab may be considered if benefits outweigh risks; maternal-fetal medicine consultation; lactation — likely minimal transfer of monoclonal antibody but not formally studied
09
Comorbidity management: CRSwNP — consider concurrent intranasal therapy; atopic dermatitis — topical therapy; GERD — proton pump inhibitor; weight management for obesity; smoking cessation; immunization (inactivated influenza annually, COVID-19, pneumococcal, complete childhood vaccinations before initiation; avoid live vaccines while on therapy)
10
Long-term considerations: continue indefinitely while providing benefit; periodic reassessment for need; consider tapering or discontinuation rarely (uncertain — most patients require continued therapy); patient education on injection technique, sharps disposal, missed dose strategy, signs to seek medical attention; multidisciplinary care (severe asthma specialist, pulmonologist, allergist-immunologist, primary care, ENT for sinus, GI for reflux, sleep medicine); patient support resources (asthma associations, manufacturer support programs)

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.