A 42-year-old woman from Bangalore with a 10-year history of asthma and chronic rhinosinusitis presents with worsening nasal obstruction and anosmia over the past 6 months. Nasal endoscopy reveals multiple bilateral nasal polyps. She is allergic to aspirin and NSAIDs, developing urticaria and bronchospasm with exposure. CT paranasal sinuses shows extensive polypoid disease with opacification of all paranasal sinuses. Biopsy of a polyp shows eosinophil-rich infiltration with eosinophil count >10 per high-power field. Which of the following is the most appropriate next step in management?