Bindu, B. J.

Glutathione synthetase (GSS) deficiency is an extremely rare autosomal recessive inborn error of metabolism. This metabolic disorder is caused by mutations in the GSS gene, which encodes GSS—an enzyme that catalyses the ATP-dependent conversion of γ-glutamyl-cysteine and glycine to glutathione. Low glutathione impairs the cellular antioxidant defence mechanism, leaving cells susceptible to oxidative stress and damage.

Abstract Immune checkpoint inhibitors (ICI) have transformed cancer therapy but can induce a spectrum of endocrine complications. Acquired generalized lipodystrophy (AGL) is a rare adverse effect, leading to severe metabolic derangements including insulin-resistant diabetes, dyslipidemia, and hepatic steatosis. Marked hypoleptinemia is noted in these patients, and leptin-replacement therapy is known to be beneficial in patients with other forms of AGL. Though rare, T-cell lymphoma has been reported in patients with AGL on leptin therapy, and there has been much debate on the association between hyperleptinemia and cancer. The safety and efficacy of leptin therapy in patients with ICI-induced AGL and cancer are therefore not clear. We report a 66-year-old woman with metastatic lung adenocarcinoma who developed multiple endocrine disorders including AGL with metabolic abnormalities following pembrolizumab therapy. Initiation of daily metreleptin led to marked improvement in dyslipidemia, glycemic control, and hepatic steatosis, with no evidence of cancer recurrence after 2 years of leptin-replacement therapy. While further studies are warranted to establish the long-term efficacy and safety of leptin in ICI-induced AGL patients with a history of malignancy, this case report provides useful information for the management of these rare, challenging patients.