The purpose of this study is to evaluate the safety and clinical pharmacology of XOMA 358 in patients with hypoglycemia after gastric bypass surgery.

Inclusion Criteria:

• Aged at least 18 years of age
• Body Mass Index < 35 kg/m2 at baseline, unless discussed with Medical Monitor and patients with higher body mass index do not have significant medical co-morbidities that would confound ability to assess safety and efficacy of study drug.
• Received gastric bypass surgery more than 1 year before dosing
• Occurrence of postprandial hypoglycemia (blood glucose less than 60mg/dL) during the Baseline provocation assessments and/or by continuous glucose monitoring, as defined in the protocol.

Exclusion Criteria:

• History of type 1 diabetes

• Planned use of the following medications on or after Day -3 (Part 1):

  • Any agent for hypoglycemia, such as diazoxide or octreotide
  • Antihyperglycemic agents, including subcutaneous insulin therapy, sulfonylureas, SGLT2 inhibitors, and GLP-1 agonists
  • Systemic glucocorticoids or β agonists that may affect glucose metabolism
  • Long-acting somatostatin analogs or glucose-affecting medications

• During Part 2, the following therapies are prohibited as specified below:

  • Tramadol and any other medications not used in the treatment of post-bariatric surgery hypoglycemia that may cause hypoglycemia or fluctuations in blood glucose levels.
  • Acetaminophen-containing products during periods of continuous glucose monitoring.

Medications such as tramadol may cause hypoglycemia or fluctuations in blood glucose levels and, as such, use of such medications is subject to the restrictions as described above during the study. Acetaminophen can interfere with the accuracy of the glucose sensor of the continuous glucose monitoring system and is, therefore, prohibited during continuous glucose monitoring.

• Major general surgery within 3 months before study entry or anticipated during the study period

Other protocol-defined inclusion/exclusion criteria may apply