Rituximab for treatment of refractory insulin autoimmune syndrome associated with non-Hodgkin B-cell lymphoma

A novel approach to a rare case of non-islet cell hypoglycaemia

SUMMARY

Insulin autoimmune syndrome (IAS) is a rare cause of non-islet cell hypoglycaemia. Treatment of this condition is complex and typically involves long-term use of glucocorticoids. Immunotherapy may provide an alternative in the management of this autoimmune condition through the suppression of antibodies production by B-lymphocyte depletion. We present a case of a 62-year-old male, with refractory hypoglycaemia initially presenting with hypoglycaemic seizure during an admission for acute psychosis. Biochemical testing revealed hypoglycaemia with an inappropriately elevated insulin and C-peptide level and no evidence of exogenous use of insulin or sulphonylurea. Polyethylene glycol precipitation demonstrated persistently elevated free insulin levels. This was accompanied by markedly elevated anti-insulin antibody (IA) titres. Imaging included CT with contrast, MRI, pancreatic endoscopic ultrasound and Ga 68-DOTATATE position emission tomography (DOTATATE PET) scan did not reveal islet cell aetiology for hyperinsulinaemia. Maintenance of euglycaemia was dependent on oral steroids and dextrose infusion. Complete resolution of hypoglycaemia and dependence on glucose and steroids was only achieved following treatment with plasma exchange and rituximab.

LEARNING POINTS

Insulin autoimmune syndrome (IAS) should be considered in patients with recurrent hyperinsulinaemic hypoglycaemia in whom exogenous insulin administration and islet cell pathologies have been excluded. Biochemical techniques play an essential role in establishing high insulin concentration, insulin antibody titres, and eliminating biochemical interference. High insulin antibody concentration can lead to inappropriately elevated serum insulin levels leading to hypoglycaemia. Plasma exchange and B-lymphocyte depletion with rituximab and immunosuppression with high dose glucocorticoids are effective in reducing serum insulin levels and hypoglycaemia in insulin autoimmune syndrome (IAS). Based on our observation, the reduction in serum insulin level may be a better indicator of treatment efficacy compared to anti-insulin antibody (IA) titre as it demonstrated greater correlation to the frequency of hypoglycaemia and to hypoglycaemia resolution.

Insulin Autoimmune Syndrome - A Case Series

Insulin autoimmune syndrome, or Hirata's disease, is a rare cause of hypoglycaemia. It is characterised by spontaneous episodes of hypoglycaemia, without any exposure to exogenous insulin. The majority of cases are seen in the Japanese population and it is rarely found to affect other ethnicities. The recognition of this disease is important to avoid unnecessary investigations and procedures. Here, we report two cases of insulin autoimmune syndrome, which were diagnosed and managed in our institute.

Recent Advances in Allogeneic CAR-T Cells

In recent decades, great advances have been made in the field of tumor treatment. Especially, cell-based therapy targeting tumor associated antigen (TAA) has developed tremendously. T cells were engineered to have the ability to attack tumor cells by generating CAR constructs consisting of genes encoding scFv, a co-stimulatory domain (CD28 or TNFRSF9), and CD247 signaling domains for T cell proliferation and activation. Principally, CAR-T cells are activated by recognizing TAA by scFv on the T cell surface, and then signaling domains inside cells connected by scFv are subsequently activated to induce downstream signaling pathways involving T cell proliferation, activation, and production of cytokines. Many efforts have been made to increase the efficacy and persistence and also to decrease T cell exhaustion. Overall, allogeneic and universal CAR-T generation has attracted much attention because of their wide and prompt usage for patients. In this review, we summarized the current techniques for generation of allogeneic and universal CAR-T cells along with their disadvantages and limitations that still need to be overcome.

Insulin Autoantibody Syndrome: Varying Clinical Presentations and Response Patterns of an Underrecognized Entity

CONTEXT

Insulin autoantibody syndrome (IAAS) is considered to be a rare cause of hyperinsulinaemic hypoglycaemia. Lack of familiarity with the varied clinical manifestations leads to underdiagnosis. Localization techniques aimed at insulin-secreting neoplasms and nesidioblastosis, which are expensive often are ordered when the correct diagnosis is not made.

AIMS

We describe the myriad of clinical manifestations associated with IAAS based on single centre experience.

SETTINGS AND DESIGN

Retrospective analysis of patients who got admitted with symptoms suggestive of hypoglycaemia and underwent mixed meal test and prolonged hypoglycaemic test from 2016 to 2019.

SUBJECTS AND METHODS

Retrospective data of 12 patients with IAAS who were diagnosed in the threeyear time period between 2016 and 2019 are included in this analysis. Clinical details, biochemical parameters and imaging modalities were analysed.

STATISTICAL ANALYSIS

All analyses were performed with SPSS software (version 17).

RESULTS

Total of twelve patients 12 (5 male and 7 females) were identified as IAAS. Median age of presentation was 57 years. Median insulin levels and median C-peptide levels were 300 miu/ml and 18.5 ng/ml respectively. Only 3 (25%) patients had spontaneous resolution. Steroid induced remission occurred by 3 months in the remaining patients. Intermittent hyperglycaemia was seen in 9 (75%) patients. Implicatable drug use preceding the occurrence of the clinical symptoms was observed in five patients.

CONCLUSION

IAAS is not uncommon in India. The diagnosis should be pursued in patients with hyperinsulinaemic hypoglycaemia especially when insulin levels are very high or when there is intermittent hyperglycaemia.