The objective of this trial was to assess the efficacy and safety of aerosolized liposomal cyclosporine A (L-CsA) as add-on therapy to standard of care (SoC) as compared to SoC alone in double lung transplant (DLT) recipients with chronic lung allograft dysfunction (CLAD)-bronchiolitis obliterans syndrome (BOS).

This was a Phase III, open-label, prospective, multicenter, randomized, controlled clinical trial of L-CsA for the treatment of BOS in adults following DLT. The patient population was recipients of a double pulmonary allograft, > or = 18 years old, with clinically defined CLAD--BOS with screening FEV1 >or = 51% of personal best FEV1 value post-transplant during the Screening period.

The rationale for an open-label study was driven by concerns that a sucrose-containing placebo formulation could increase a potential risk of pulmonary infection without the benefit of L-CsA. Sucrose is a lyoprotectant in the manufacturing process. After carefully considering alternative options for lyoprotection, no sugar-free alternatives that would qualify as a real placebo (i.e., undistinguishable by means of appearance, taste, or smell) could be identified.

Therefore, an open-label, randomized controlled trial versus SoC was the only suitable alternative.

An open-label clinical trial generally bears the potential for bias in patient treatment and care, and thus trial outcome. However, for this trial the risk of bias is considered low because of the following reasons:

• During the trial, the general treatment of BOS was use of immunosuppressive therapy to the highest tolerable level unless limited by systemic toxicity. As inhaled L-CsA has not been associated with additional systemic drug burden, dose reductions or adaptations of other components of the immunosuppressive cocktail would not be required and were not desired.
• The selected primary endpoint FEV1 is an objective parameter and its measurement was performed according to recommended guidelines of American Thoracic Society (ATS)/European Respiratory Society (ERS) which had to be respected by each participating center. Following this methodology, a subjective and intentional manipulation of outcome was highly unlikely even if healthcare professional and patient were aware of the treatment allocation.
• Pulmonary function technicians, respiratory therapists, or physiotherapists who performed spirometry at each site were blinded to each patient's study treatment assignment.
• Finally, the correctness and validity of individual FEV1 curves and their resulting value had to be approved in a central and blinded reading by a pulmonary expert who was independent and not involved in patient care or treatment. The implementation of these measures should have ensured that the reported data of the primary outcome was as free as possible of bias induced by the open-label trial design.

Stratification prior to randomization was performed to limit imbalances between treatment arms with respect to key variables and potential confounders.

There were major recruitment issues in both the BOSTON-1 trial (SLT recipients) and the present BOSTON-2 trial, in part due to Coronavirus disease-2019 (COVID-19) and specifically in BOSTON-1 due to a marked decline over time in the use of SLT. Following FDA recommendation to obtain an adequately sized safety database for inhaled L-CsA and reach the originally planned sample size for BOSTON-1 and BOSTON-2 trials combined, it was planned to stop randomization into the two Phase III clinical trials upon achievement of a combined total of approximately 220 patients, of which approximately 160 to 170 patients were planned for enrollment in BOSTON-2. To assure balance between treatment arms with regard to key variables and potential confounders, stratification prior to randomization was performed. Within each of the 8 strata, using a permuted blocks randomization, patients were randomly assigned with equal probability (1:1) to receive either L-CsA (10 mg) via the PARI eFlow Nebulizer System twice daily (BID) plus SoC treatment or SoC alone, for a period of 48 weeks. Patients were monitored every 4 to 8 weeks over 48 weeks for efficacy parameters and for all safety evaluations. All patients were eligible to continue in an open-label extension trial of L-CsA, BOSTON-3 (Study BT-L-CsA-303-FU) following completion of either BOSTON-1 or BOSTON-2.

Up to 11 visits (Screening, V1 through V10) were planned during the clinical trial. After informed consent had been obtained, a Screening Visit was carried out to check general eligibility for participation. At the Baseline Visit (V1, Randomization Visit), inclusion and exclusion criteria were re-checked, and Baseline serial spirometry was performed. During the 48-week treatment period, visits were scheduled every 4 to 8 weeks (V2 to V9). Visit 9 (End of Treatment [EoT) was scheduled to occur 48 weeks after Visit 1. If a patient had an event that met the first criterion for progression of BOS, progression of BOS must have been confirmed by measurements that were taken with COMPACT spirometer at least 2 weeks apart. Visit 10 (EoS) was a safety follow-up visit performed 4 weeks after Visit 9/EoT only in patients not rolling over to the extension study (BOSTON-3). For patients who rolled over to BOSTON-3, the EoT Visit was the EoS Visit. Every effort was made to have all planned and unscheduled visits at the study site. However, if one of the visits from Visit 2 to Visit 8 and discontinuation visits could not be performed at the site due to COVID-19, remote visits (e.g., by telephone) were possible. Mandatory on-site visits were Screening Visit, Visit 1, and Visit 9.](streamdown:incomplete-link)

Inclusion Criteria:

Patients who met the following criteria as stated in the protocol were included in the study:

1. Adult patients of > or = 18 years who received a DLT at least 12 months prior to Screening.

2. Patients with BOS diagnosis defined as CLAD-BOS phenotype with:

   1. screening FEV1 between 51% and 85% of personal best FEV1 value post-transplant OR
   2. screening FEV1 > 85% of personal best FEV1 associated with EITHER a > or = 200 mL decrease in FEV1 in the previous 12 months OR according to medical history showing BOS progression.

3. Diagnosis of CLAD-BOS must have been made at least 12 months after lung transplantation and

   1. within 12 months prior to the Screening Visit OR
   2. more than 12 months from Screening and patient must have shown a decline in FEV1 >or = 200 ml in the previous 12 months before Screening, which was not due to acute infection or acute organ rejection.

4. Patients in whom the diagnosis of BOS had been confirmed by the elimination of other possible causes of obstructive or restrictive lung disease CLAD - restrictive allograft syndrome (RAS) phenotype.

5. Patients should have been on a drug maintenance regimen of immunosuppressive agents including tacrolimus, a second agent such as but not limited to MMF or azathioprine, and a systemic corticosteroid such as prednisone as third agent. The regimen must have been stable within 4 weeks prior to randomization with respect to the therapeutic agents. In case a patient was also receiving concomitant azithromycin for prophylaxis or treatment of BOS, in addition to the previously described immunosuppressive regimen, azithromycin must have been on a stable regimen for at least 4 weeks prior to randomization.

6. Patients capable of understanding the purposes and risks of the clinical trial, who had given written informed consent and agreed to comply with the clinical trial requirements/visit schedules, and who were capable of aerosol inhalation. Patients must have consented to retrieve prespecified data from the historic medical record (e.g., information related to the transplant surgery; spirometry data; medication use).

7. Women of childbearing potential must have had a negative serum or urine pregnancy test within 7 days prior to randomization and must have agreed to use one of the methods of contraception listed in Appendix II of the protocol in Appendix 16.1.1 through their EoS Visit.

8. Patients had no concomitant diagnoses that were considered fatal within one year (12 months) of Screening.

Exclusion Criteria:

1. Patients with confirmed other causes for loss of lung function, such as acute infection, acute rejection, restrictive allograft syndrome (RAS) (CLAD - RAS phenotype, see Protocol Specific Definition ), etc.
2. Cystic Fibrosis patients with multi-drug resistant infections not responding to available anti-microbial therapies.
3. Patients with acute antibody-mediated rejection at Screening. In this context, clinically stable patients (as judged by the Investigator) with detectable levels of donor specific antibodies (DSA) at the Screening Visit are eligible for the study.
4. Active acute bacterial, viral, or fungal infection not successfully resolved at least 4 weeks prior to the Screening Visit. Patients with chronic infection or colonization who are clinically stable as per judgement of the Investigator are eligible for the study.
5. Mechanical ventilation (including CPAP) within 12 weeks prior to Randomization.
6. Patients with uncontrolled hypertension.
7. Patient has baseline resting oxygen saturation of < 89% on room air or use of supplemental oxygen at rest.
8. Evidence of functional airway stenosis (e.g., bronchomalacia/tracheomalacia, airway stents, or airways requiring balloon dilatations to maintain patency) with onset after the initial diagnosis of BOS and ongoing at Screening and/or Randomization Visit.
9. Known hypersensitivity to L-CsA or to cyclosporine A.
10. Patients with chronic renal failure, defined as serum creatinine > 2.5 mg/dL at screening, or requiring chronic dialysis.
11. Patients with liver disease and serum bilirubin > 3-fold upper limit of normal range or transaminases > 2.5 upper limit of normal range.
12. Patients with active malignancy within the previous 2 years, including post-transplant lymphoproliferative disorder, with the exception of treated, localized basal and squamous cell carcinomas.
13. Pregnant women or women who are unwilling to use appropriate birth control to avoid pregnancy through their End of Study Visit.
14. Women who are currently breastfeeding.
15. Receipt of an investigational drug as part of a clinical trial within 4 weeks prior to the Screening Visit. This is defined as any treatment that is implemented under an Investigational New Drug (IND) or compassionate use.
16. Patients who have received extracorporeal photophoresis (ECP) for treatment of BOS within 1 month prior to Randomization.
17. Patients who are currently participating in an interventional clinical trial.
18. Psychiatric disorders or altered mental status precluding understanding of the informed consent process and/or completion of the necessary procedures.
19. Any co-existing medical condition that in the Investigator's judgment will substantially increase the risk associated with the patient's participation in the clinical trial.