Proportion of Participants Who Experienced an Objective Response Defined as Either a Partial or Complete Response

Dose Level 1: 400 mcg LMB-100

Dose Level 1: 400 mcg LMB-100 administered per dose, dose administered on days 1 and 4 of 21-day cycle, cycle 1 in participants with pleural or peritoneal mesothelioma. Those with pleural or peritoneal mesothelioma receiving intra-tumoral administration of LMB-100 + Ipilimumab for up to 4 cycles. For infusion related reactions precaution, all participants will be premedicated 30-60 minutes (+ 30 minutes) prior to each LMB-100 administration with the following medications: Diphenhydramine 25-50 mg by mouth (PO) or intravenous (IV) (or alternative antihistamine at adequate dose), Famotidine 20 mg by mouth (PO) or intravenous (IV) (or alternative histamine H2- receptor antagonists (H2) blocker at adequate dose), and Acetaminophen 650 mg by mouth (PO) or intravenous (IV). Additional infusion precaution at infusions of LMB-100 after Cycle 1 Day 1 (as appropriate): Dexamethasone 20 mg by mouth (PO), 6-12 hours prior to LMB-100 administration OR 10mg, intravenous (IV), 30-60 minutes prior to LMB-100 administration OR equivalent dose of another corticosteroid as clinically indicated. Biopsy as feasible at screening, Cycle 1 Day 1 and 5, Cycle 2, 3, \& 4 Day 1, and Cycle 4 Day 21 (±7 days).

Analysis denominator · Participants