Endocrine Abstracts

Background: Lung cancers are one of the leading causes of death worldwide which has resulted in an increase in immunotherapy, particularly immune checkpoint inhibitors (ICIs). Recent studies have shown induced endocrinopathies secondary to ICIs as a result of pancreatic beta cells, thyroid, and pituitary dysfunction.

Aim: We aim to present an interesting case of Type 1 Diabetes mellitus secondary to immunotherapy. Pembrolizumab is used to treat melanoma, non-small cell lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, and cervical cancer. Pembrolizumab is a human monoclonal IgG4 antibody that selectively binds to programmed cell death ligand-1 (PD1) receptor on the cell surface, thus blocking PD-1 (Programmed cell Death 1) which prevents T-cells from recognising and attacking cancer cells.

Case: In this case, a 62-year-old lady presented to hospital with polyuria, polydipsia, and weight loss after 8 months of immunotherapy. She was found to be hyperglycaemic and new of type 1 diabetes. Her background includes poorly differentiated adenocarcinoma of right lung diagnosed in March 2017, dermatomyositis, and an ex-smoker. She had received 4 cycles of chemotherapy (Cisplatin/Pemetrexed) between April 2017- June 2017 and then radical radiotherapy which completed August 2017 with good response and then she commenced Pembrolizumab in July 2020. Initial investigations were not consistent with DKA; pH 7.431, serum glucose 29.7 mmol/l, HCO3 26.2 mmol/l and urinary ketones 4+. She was commenced on NovoRapid 4 units 3 times a day and Levemir 10 units in the morning and 4 units in the evening. TSH was 0.90 mU/l and cortisol of 263 nmol/l excluded adrenal insufficiency. She was negative for Islets-cell antibodies, anti-GAD antibodies, and ZNT8.

Discussion: ICIs are commonly associated with endocrinopathies which are categorized as immune-related adverse events (Ruggeri 2019). New type 1 diabetes mellitus is a frequent toxicity of immunotherapy and can potentially be life-threatening if not diagnosed promptly. Therefore, during immunotherapy treatment, serum glucose should be regularly monitored. The UK National Institute of Health and Care Excellence (NICE) recommends developing an early plan of care, blood glucose management (periodic HbA1c and serum fasting glucose level tests), and managing long-term complications for adults diagnosed with Type 1 Diabetes mellitus. It is also recommended that patients started on ICIs have other endocrine toxicities testing. Current treatment is targeted to replace the specific hormone deficiency, e.g insulin in the case of new T1DM, as well as immunosuppression depending on the severity of the endocrinopathy (Ruggeri 2019).