What is the treatment for severe asthma in adolescents?

Hi doctor,

My 14-year-old son has severe asthma that has been impossible to control despite multiple medications. He takes Advair twice daily, Montelukast 10 mg at night, Spiriva once daily, plus frequent Albuterol treatments. Even with all that, he has been hospitalized seven times in the past year, including two ICU stays where he nearly needed intubation. His pulmonologist recently started him on Tezspire after Xolair and Nucala both failed to help. He had two injections so far (one every four weeks) but we have not seen any improvement yet. He had another severe attack last night requiring an emergency room visit where they gave him three breathing treatments and prednisone. His pulmonary function tests show FEV1 at 52 % of predicted, and blood tests show an eosinophil count of 680 cells/μL. He misses so much school that he has fallen behind academically despite being a bright kid. He had to quit the baseball team which devastated him. His asthma triggers seem to be exercise, cold air, respiratory infections, and possibly certain foods though we have not identified specific ones. The constant steroids have affected his growth - he is the shortest boy in his class and gets teased about it. How long should we expect before Tezspire starts working? Is there anything else we can try if this fails too? His allergist mentioned bronchial thermoplasty but said it is rarely done in adolescents. My son's quality of life is terrible and I am desperate to find something that helps.

Thanks.