NEW TREATMENT

1 . A method of treating chronic obstructive pulmonary disease (COPD) in a subject, the method comprising administering to the subject a composition comprising ensifentrine or a pharmaceutically acceptable salt thereof,

wherein the subject has a blood eosinophil count of less than 300 cells/μL,

wherein the method reduces frequency of COPD exacerbations or severity of COPD exacerbations in the subject compared to frequency of COPD exacerbations or severity of COPD exacerbations in an untreated subject having COPD and not administered the composition.

2 . The method of claim 1 , wherein the method decreases the frequency of COPD exacerbations or the severity of COPD exacerbations in the subject by at least 20% compared to the frequency of COPD exacerbations or the severity of COPD exacerbations in the untreated subject having COPD and not administered the composition.

3 . The method of claim 2 , wherein the method decreases the frequency of COPD exacerbations or the severity of COPD exacerbations in the subject by at least 40% compared to the frequency of COPD exacerbations or the severity of COPD exacerbations in the untreated subject having COPD and not administered the composition.

4 . The method of claim 1 , wherein the method increases time to first COPD exacerbation in the subject compared to time to first COPD exacerbation in the untreated subject having COPD and not administered the composition.

5 . The method of claim 1 , wherein the subject has a blood eosinophil count of less than 150 cells/μL.

6 . The method of claim 1 , wherein the subject has a blood eosinophil count of less than 100 cells/μL.

7 . The method of claim 1 , wherein the blood eosinophil count is determined from a sample of blood obtained from the subject using a Coulter counter.

8 . The method of claim 1 , wherein the subject is susceptible to COPD exacerbations.

9 . The method of claim 1 , wherein the subject has suffered one or more COPD exacerbations in a year preceding the administering to the subject.

10 . The method of claim 1 , wherein the subject is susceptible to pneumonia.

11 . The method of claim 1 , wherein the subject is not on an inhaled corticosteroid regimen at a time of the administering to the subject.

12 . The method of claim 1 , wherein the composition is administered to the subject via inhalation.

13 . The method of claim 1 , wherein the administering to the subject is once, twice or three times per day.

14 . The method of claim 13 , wherein the administering to the subject is twice a day.

15 . The method of claim 1 , wherein the administering to the subject comprises a total daily dose of the ensifentrine or the pharmaceutically acceptable salt thereof of from 0.5 to 10 mg.

16 . The method of claim 15 , wherein the administering to the subject comprises a dose of about 3 mg of the ensifentrine or the pharmaceutically acceptable salt thereof to the subject twice a day.

17 . The method of claim 1 , wherein the administering to the subject comprises administering the ensifentrine or the pharmaceutically acceptable salt thereof to the subject at least once per day for at least 8 weeks, at least 16 weeks, or for at least 24 weeks.

18 . The method of claim 1 , wherein the composition is an inhalable pharmaceutical composition comprising a diluent.

19 . The method of claim 18 , wherein the inhalable pharmaceutical composition comprises:

(a) particles comprising the ensifentrine or the pharmaceutically acceptable salt thereof at a concentration of 1.2 mg/mL;

(b) polysorbate 20 at a concentration of 0.5 mg/mL;

(c) sorbitan monolaurate at a concentration of 0.05 mg/mL;

(d) sodium dihydrogen phosphate dihydrate at a concentration of 0.744 mg/mL;

(e) disodium hydrogen phosphate dihydrate at a concentration of 0.853 mg/mL; and

(f) sodium chloride at a concentration of 8.6 mg/mL.

20 . The method of claim 1 , wherein the composition is administered to the subject in combination with a muscarinic receptor antagonist, a beta-adrenergic receptor agonist or an inhaled corticosteroid.