RecruitingEarly Phase 1Biological interventionAlteplase Through an Indwelling Pleural Catheter for the Management of Symptomatic Septated Malignant Pleural EffusionThis study investigates whether alteplase can help to improve pleural fluid drainage and dyspnea (breathlessness) in patients with non-draining malignant pleural effusion. Alteplase helps dissolve blood clots and is used to treat heart attacks, strokes, and clots in the lungs. Alteplase may help to control symptoms of breathlessness.