TREATMENT

1 . A method for treating chronic obstructive pulmonary disease (COPD) in a patient suffering from COPD who is resistant to improvements in lung function comprising administering to the resistant patient a therapeutically effective amount of an inhalable pharmaceutical composition comprising ensifentrine or a pharmaceutically acceptable salt thereof in an amount effective for (i) improving the symptoms of COPD in the resistant patient and/or (ii) improving the quality of life of the resistant patient.

2 . The method of claim 1 , wherein the patient resistant to improvements in lung function is a patient who demonstrates a low FEV 1 response relative to baseline following a reference COPD treatment.

3 . The method of claim 2 , wherein the low FEV 1 response relative to baseline comprises an increase in morning trough FEV 1 of less than about 60 mL.

4 . The method of claim 2 , wherein the low FEV 1 response relative to baseline is as measured following treatment with the reference COPD treatment for at least 6 weeks.

5 . The method of claim 2 , wherein the reference COPD treatment comprises treatment with one or more bronchodilators.

6 . The method of claim 1 , wherein the patient resistant to improvements in lung function is a patient who demonstrates an increase in FEV 1 AUC 0-12h of less than 100 mL relative to baseline and/or an increase in morning trough FEV 1 of less than 100 mL relative to baseline following daily administration of ensifentrine for a period of at least six weeks.

7 . The method of claim 1 , wherein the patient has a baseline FEV 1 of at least 1500 mL, at least 2000 mL or at least 2500 mL.

8 . The method of claim 1 , wherein the patient is suffering from moderate COPD, severe COPD or very severe COPD.

9 . The method of claim 1 , wherein the patient is suffering from irreversible COPD.

10 . The method of claim 1 , wherein treating COPD comprises improving the symptoms of COPD in the patient.

11 . The method of claim 1 , wherein treating COPD comprises:

(i) improving the symptoms of COPD in the patient as determined by a reduction of at least 2 in the Evaluating Respiratory Symptoms (E-RS) score of the patient or an increase of at least 1 in the Transitional Dyspnea Index (TDI) score of the patient; or

(ii) improving the quality of life of the patient as determined by a reduction of at least 4 in the St. George's Respiratory Questionnaire (SGRQ) score of the patient.

12 . The method of claim 11 , wherein the changes in E-RS, TDI or SGRQ score are achieved at least 12 weeks after the patient is first treated with the inhalable pharmaceutical composition.

13 . The method of claim 1 , wherein the method comprises administering the inhalable pharmaceutical composition to the patient by inhalation.

14 . The method of claim 1 , wherein the method comprises administering the inhalable pharmaceutical composition to the patient once, twice or three times per day.

15 . The method of claim 1 , wherein the method comprises administering the inhalable pharmaceutical composition as a maintenance therapy.

16 . The method of claim 1 , wherein the method comprises administering a total daily dose of the compound of from 0.5 to 10 mg.

17 . The method of claim 1 , wherein the method comprises administering the compound to the patient twice a day in a first dose of from 2 to 4 mg and a second dose of from 2 to 4 mg.

18 . The method of claim 1 , wherein the method comprises administering a dose of about 3 mg of the compound to the patient twice a day (3 mg BID).

19 . The method of claim 1 , wherein the method comprises administering the inhalable pharmaceutical composition to the patient at least once per day for at least 8 weeks.

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

21 . The method of claim 1 , wherein the inhalable pharmaceutical composition comprises a suspension of ensifentrine particles comprising the ensifentrine or a pharmaceutically acceptable salt thereof in a diluent.

22 . The method of claim 21 , wherein the inhalable pharmaceutical composition comprises:

a. ensifentrine particles;

b. a buffer;

c. one or more surfactants; and

d. a tonicity adjuster,

wherein a total weight of the ensifentrine or the pharmaceutically acceptable salt thereof in the liquid pharmaceutical composition is of from about 2.7 mg to about 3.3 mg.

23 . The method of claim 21 , wherein the inhalable pharmaceutical composition comprises:

a. ensifentrine particles at a concentration of from about 1 mg/mL to about 1.4 mg/mL;

b. a buffer at a concentration of from about 1 mg/mL to about 2 mg/mL;

c. one or more surfactants at a total concentration of from about 0.01 mg/mL to about 0.8 mg/mL; and

d. a tonicity adjuster at a concentration of from about 5 mg/mL to about 10 mg/mL.

24 . The method of claim 21 , wherein the inhalable pharmaceutical composition comprises:

a. ensifentrine particles at a concentration of from about 1 mg/mL to about 1.4 mg/mL;

b. polysorbate 20 (Tween 20) at a concentration of from about 0.3 mg/mL to about 0.7 mg/mL;

c. sorbitan monolaurate (Span 20) at a concentration of from 0 mg/mL to about 0.1 mg/mL;

d. sodium dihydrogen phosphate dihydrate at a concentration of from about 0.5 mg/mL to about 1 mg/mL;

e. disodium hydrogen phosphate dihydrate at a concentration of from about 0.5 mg/mL to about 1 mg/mL; and

f. sodium chloride at a concentration of from about 5 mg/mL to about 10 mg/mL.

25 . The method of claim 21 , wherein the inhalable pharmaceutical composition comprises:

a. 1.2 mg/mL ensifentrine particles;

b. 0.5 mg/mL polysorbate 20;

c. 0.05 mg/mL sorbitan monolaurate;

d. 0.744 mg/mL sodium dihydrogen phosphate dihydrate;

e. 0.853 mg/mL disodium hydrogen phosphate dihydrate;

f. sodium chloride at a concentration of 8.6 mg/mL; and

g. water.

26 . The method of claim 21 , wherein the inhalable pharmaceutical composition is a suspension comprising:

a. 1.4 mg/mL ensifentrine particles;

b. 0.55 mg/ml polysorbate 20;

c. 0.744 mg/ml sodium dihydrogen phosphate dihydrate;

d. 0.853 mg/ml disodium hydrogen phosphate dihydrate;

e. 8.6 mg/ml sodium chloride; and

f. water.

27 . The method of claim 21 , wherein the inhalable pharmaceutical composition is a suspension comprising:

a. 1.3 mg/mL ensifentrine particles;

b. 0.55 mg/ml sorbitan monolaurate;

c. 0.744 mg/ml sodium dihydrogen phosphate dihydrate;

d. 0.853 mg/ml disodium hydrogen phosphate dihydrate;

e. 8.6 mg/ml sodium chloride; and

f. water.

28 . The method of claim 21 , wherein the inhalable pharmaceutical composition is a suspension comprising:

a. 1.3 mg/mL ensifentrine particles;

b. 0.5 mg/ml polysorbate 20;

c. 0.05 mg/ml sorbitan monolaurate;

d. 1.1 mg/ml sodium dihydrogen phosphate dihydrate;

e. 0.9 mg/ml disodium hydrogen phosphate dihydrate;

f. 13 mg/ml sodium chloride; and

g. water.

29 . The method of claim 21 , wherein the inhalable pharmaceutical composition is a suspension comprising:

a. 1.2 mg/mL ensifentrine particles;

b. 0.4 mg/ml polysorbate 20;

c. 0.10 mg/ml sorbitan monolaurate;

d. 0.744 mg/ml sodium dihydrogen phosphate dihydrate;

e. 0.853 mg/ml disodium hydrogen phosphate dihydrate;

f. 8.6 mg/ml sodium chloride; and

g. water.

30 . The method of claim 21 , wherein the inhalable pharmaceutical composition is a suspension comprising:

a. 1.4 mg/mL ensifentrine particles;

b. 0.4 mg/ml polysorbate 20;

c. 0.04 mg/ml sorbitan monolaurate;

d. 1.2 mg/ml sodium dihydrogen phosphate dihydrate;

e. 8.6 mg/ml sodium chloride; and

f. water.

31 . The method of claim 21 , wherein the inhalable pharmaceutical composition comprises:

a. the ensifentrine particles at a concentration of from 0.8 to 1.4 mg/mL;

b. one or more surfactants at a total concentration of from 0.3 to 0.7 mg/mL;

c. one or more buffers at a total concentration of from 1.0 to 2.0 mg/ml;

d. one or more tonicity adjusters at a concentration of from 1.0 to 15.0 mg/ml and

e. water.