A Study to Evaluate the Safety and Efficacy of BEAM-302 in Adult Patients With Alpha-1 Antitrypsin Deficiency (AATD)

Part A: Key Inclusion Criteria: * Age 18-70 years. * Confirmed PiZZ AATD diagnosis. * Blood total AAT level \<11 μM. * Willing to discontinue augmentation therapy as required by protocol. * A postbronchodilator FEV1 ≥40% (Ph 1) of predicted or ≥35% (Ph 2) and an FEV1/FVC \<70% at screening (Ph 1 only). * Evidence of emphysema on chest imaging. Key Exclusion Criteria: * BMI \>30. * Lung or liver transplant or on waiting list for lung or liver transplant or status post lung volume reduction. * Clinical evidence of severe bronchiectasis. * Significant liver disease as defined in the protocol. * Active hepatitis A, B or C infection Part B: Key Inclusion Criteria: * Age 18-70 years. * Confirmed PiZZ AATD diagnosis. * Clinical diagnosis of AATD-related liver disease along with evidence of METAVIR F1, F2, or F3 liver fibrosis. * A postbronchodilator FEV1 ≥40% (Phase 1) or ≥35% (Phase 2) of predicted at screening. * FibroScan ≤12 kPa. Key Exclusion Criteria: * Lung or liver transplant or on waiting list for lung or liver transplant or status post lung volume reduction. * Clinical evidence of severe bronchiectasis. * Previous diagnosis of liver cirrhosis or complications of cirrhosis. Part C: Key Inclusion Criteria: * Age 18-75 years. * Confirmed PiZZ AATD diagnosis. * Willing to discontinue augmentation therapy as required by protocol. * A postbronchodilator FEV1 ≥30% of predicted. * Evidence of emphysema chest imaging. * Liver stiffness \<12 kPa. Key Exclusion Criteria: * Lung or liver transplant or on waiting list for lung or liver transplant or status post lung volume reduction. * Clinical evidence of severe bronchiectasis. * BMI \>40. * Known history of liver cirrhosis or complications of cirrhosis.