The purpose of this study is to evaluate the safety and tolerability of a single intravenous dose of MP101 administered in addition to standard antibiotic therapy in adult patients with acute Pseudomonas aeruginosa pneumonia. The study will also assess the pharmacokinetic and pharmacodynamic characteristics of MP101 and its antibacterial activity, including changes in P. aeruginosa burden in sputum and changes in susceptibility to MP101 and concomitant antibiotics.

This is a randomized, double-blind, placebo-controlled, single-dose, dose-escalation phase 1 study in adult patients with acute Pseudomonas aeruginosa pneumonia. Approximately 18 participants will be enrolled at about 6 study sites in Korea. Participants will be assigned to either a low-dose cohort or a high-dose cohort and will receive MP101 or matching placebo in addition to standard antibiotic therapy. Escalation to the high-dose cohort will occur after review of available safety data by the Safety Review Committee.

The study is designed to evaluate the safety and tolerability of MP101 and to characterize its pharmacokinetic and pharmacodynamic profile in blood and sputum. The study will also assess antibacterial activity against Pseudomonas aeruginosa, including changes in sputum bacterial burden and changes in susceptibility to MP101 and concomitant antibiotics. Additional exploratory assessments include inflammatory biomarkers and clinical outcome measures in patients with acute pneumonia.

After screening within 7 days before dosing, participants will receive study treatment on Day 1 and remain under inpatient observation through Day 8 for safety and PK/PD assessments. Follow-up visits will be conducted on Day 15 and Day 29. Study assessments include adverse events, clinical laboratory tests, vital signs, electrocardiograms, microbiologic evaluations in sputum, and protocol-defined exploratory assessments.

Inclusion Criteria:

• Subjects aged 19 years or older.
• Clinical diagnosis of acute pneumonia with radiologic evidence of pulmonary infiltrates.
• Confirmed Pseudomonas aeruginosa (PA) infection via valid respiratory specimens.
• PA isolate demonstrates susceptibility to MP101 and non-susceptibility to current antibiotic therapy.
• Adequate organ function as defined by hematological, hepatic, and renal laboratory parameters .

Exclusion Criteria:

• Persistent septic shock or hemodynamically unstable condition.
• Active pulmonary tuberculosis or suspected non-bacterial pneumonia.
• Significant pleural effusion or lung abscess requiring therapeutic drainage.
• Clinically significant cardiovascular, hepatic, or renal impairment .
• Immunocompromised status or history of hematological malignancies.
• Known hypersensitivity to bacteriophages, study components, or concomitant antibiotics.
• Participation in another clinical trial within 30 days prior to screening.
• Any medical condition that, in the opinion of the investigator, would make the subject unsuitable for the study.

There is no current plan to provide access to individual participant data to other researchers.