D1.146 - Improved nocturnal oxygenation in a severe allergic asthma patient with comorbid sleep apnea under anti-TSLP biologic therapy

Introduction: Severe asthma (SA) and obstructive sleep apnea (OSA) frequently coexist, especially in obese patients. Asthma patients have a 2.64 fold higher risk of developing OSA. The presence of OSA may compromise nocturnal asthma control. Systemic corticosteroids (SCS) required for the control of SA may contribute to pharyngeal alterations and obesity, thus promoting OSA. Case description: We present the case of a 43–years old, former smoker (10 P.Y.), female patient with allergic SA (sensitization to HDM and acacia pollen) and multiple comorbidities, including obesity (BMI=45kg/m²). Lung function was severely impaired (FEV1=45%, FEV1/FVC ratio<70%) and despite optimized inahled therapy (high dose ICS+LABA since 2019, triple therapy since 2023) asthma control remained poor (ACT score < 15). In 2023 she had 3 documented episodes of exacerbations requiring SCS. In Sep 2023 a sleep study revealed mild to moderate OSA (AHI=14.4/h, DI=17.8/h), but with significant O₂ desturation during sleep (t90%=77.6%, Mean SaO₂=87.1%). The patient refused CPAP and was initiated on nocturnal oxygen therapy. She was lost to follow-up for >1 year. In Jan 2025 she was hospitalized for severe exacerbation with type 2 respiratory failure. Upon discharge she was recommended nocturnal BiPAP therapy which was discontinued in Apr 2025. Biologic therapy with tezepelumab was started in Jun 2025 with good clinical response (ACT score > 20), lung function improvement (FEV1=71% after 6 months), no further exacerbations. A repeat sleep study after 4 months of biologic therapy revealed mild OSA (AHI=11.4/h, DI=14.4/h) and improved nocturnal oxygenation (t90%=9.4%, Mean SaO₂=92.2%), despite BMI increase. Discussion: Several studies have analyzed the impact of OSA treatment with CPAP on asthma outcomes in patients with both conditions with conflicting results. Few, if any studies however, have reported on the effect on the sleep parameters of achieved asthma control. Here we report the case of a SA patient with comorbid OSA and significant nocturnal desaturation in whom achieveing asthma control under therapy with tezepelumab was associated with significant improvement in nocturnal oxygenation. Conclusion: Achieving good asthma control may significantly improve nocturnal oxygenation and OSA severity, even in the absence of CPAP and despite persistent obesity. Optimizing asthma control may therefore play an important role in the management of sleep-disordered breathing in patients with SA.