This is a 2-part, prospective, randomized, blinded, sham-controlled, multi-center study comparing preterm subjects with RDS who are treated with APC-0101 and nCPAP/NIV to subjects treated with nCPAP/NIV alone (Sham). In Part 1, subjects will be followed until they reach 40 weeks post-menstrual age (PMA) or are discharged from the NICU, whichever comes first. In Part 2, subjects will undergo post-term follow-up through 24 months corrected age.

Inclusion Criteria:

1. Inborn at the study site's hospital (i.e., not transferred from another hospital following delivery)
2. Gestational age at birth of 26 through 33 weeks PMA
3. Birth weight appropriate for gestational age (AGA, weight 3rd to 97th percentile on Fenton Growth Curve)
4. Birth weight ≤ 2000 grams
5. Post-natal age 1 to 24 hours at randomization
6. On nCPAP or NIV for at least 30 minutes with RSS = 1.4 - 2.0 to maintain SpO2 90-95% at randomization. RSS is calculated as (nCPAP cm H2O) × (FiO2) or as (NIV mean airway pressure cm H2O) × (FiO2).
7. FiO2 ≥ 0.24 at randomization
8. nCPAP or mPaw ≥ 6 cm H2O at randomization
9. Chest radiograph (CXR) or lung ultrasound compatible with RDS prior to randomization

Exclusion Criteria:

1. On SiPAP®, RAM® cannula, or high flow nasal cannula (HFNC) (> 2 liters per minute [LPM]) at the time of randomization
2. Prior instillation of surfactant
3. Premature rupture of membranes (PROM) occurring > 14 days before birth
4. Significant congenital/chromosomal anomaly (e.g., Pierre Robin syndrome, clinically significant congenital heart disease, or trisomy)
5. Pneumothorax
6. Other etiologies of respiratory distress
7. Enrollment in another interventional study with similar efficacy endpoints
8. Apgar score at 5 min of 0-3
9. Prior cardiopulmonary resuscitation (CPR) or epinephrine
10. Base Deficit > 15 mEq/L on most recent arterial blood gas (not capillary blood gas, venous blood gas, or cord gas) prior to randomization. Note that arterial blood gas is not required prior to randomization.
11. Partial pressure of carbon dioxide (PaCO2) > 65 mmHg on most recent arterial blood gas (not capillary blood gas, venous blood gas, or cord gas) prior to randomization.
12. Triplet or higher order multiple birth

Blinding/masking will be accomplished by a two-level redundant process. First, a screen (or private room) will be placed around the subject's bedside area and the APC-0101 Controller during APC-0101 or Sham treatment. This will ensure that no members of the clinical team, other than the blinded bedside nurse, will see the subject or the Controller throughout treatment. Second, the Controller and subject's face will be shielded so the blinded bedside nurse cannot determine whether the subject is receiving APC-0101 or Sham treatment.

A trained, unblinded, staff member (e.g., a respiratory therapist) will set up the Controller, but will not be involved with making decisions about the respiratory support of the subject.

Parents and all members of the clinical team who will make decisions about respiratory support, including FiO2, assessment of Failure Criteria, or assessment of AEs, will remain blinded throughout the study.