The
n e w e ng l a n d j o u r na l
of
m e dic i n e
brief report
Sirolimus Therapy in Infants with Severe Hyperinsulinemic Hypoglycemia Senthil Senniappan, M.D., Sanda Alexandrescu, M.D., Nina Tatevian, M.D., Pratik Shah, M.D., Ved Arya, M.D., Sarah Flanagan, Ph.D., Sian Ellard, Ph.D., Dyanne Rampling, F.I.B.M.S., Michael Ashworth, M.D., Robert E. Brown, M.D., and Khalid Hussain, M.D.
SUM M A R Y Hyperinsulinemic hypoglycemia is the most common cause of severe, persistent neonatal hypoglycemia. The treatment of hyperinsulinemic hypoglycemia that is unresponsive to diazoxide is subtotal pancreatectomy. We examined the effectiveness of the mammalian target of rapamycin (mTOR) inhibitor sirolimus in four infants with severe hyperinsulinemic hypoglycemia that had been unresponsive to maximal doses of diazoxide (20 mg per kilogram of body weight per day) and octreotide (35 μg per kilogram per day). All the patients had a clear glycemic response to sirolimus, although one patient required a small dose of octreotide to maintain normoglycemia. There were no major adverse events during 1 year of follow-up.
H
yperinsulinemic hypoglycemia, a major cause of severe hypoglycemia during the neonatal period, is characterized by inappropriate insulin secretion from pancreatic beta cells in the presence of low blood glucose levels.1 The condition may result from defects in key genes involved in the regulation of insulin secretion from beta cells, including ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A, HNF1A, and UCP2.1,2 Two major histologic subtypes have been described: diffuse and focal.3 Mutations in ABCC8 and KCNJ11 are associated with severe hyperinsulinemic hypoglycemia that is unresponsive to medical treatment with diazoxide and octreo tide.1 The only treatment option currently available for patients with medically unresponsive forms of diffuse hyperinsulinemic hypoglycemia is a subtotal pancreatectomy, in which 95 to 98% of insulin-secreting cells are physically removed to alleviate the severe hypoglycemia. However, some patients who have undergone surgery continue to have recurrent hyperinsulinemic hypoglycemia, whereas diabetes mellitus and exocrine pancreatic insufficiency develop in others. In a recent study of 105 affected children who underwent pancreatectomy, 59% had persistent hyperinsulinemic hypoglycemia up to 5 years after surgery, and diabetes mellitus had developed in all the children by the time they reached early adolescence.4 Hence, there is a need for a medical therapy that can be used as an alternative to subtotal pancreatectomy. A possible mechanism of hyperinsulinism and beta-cell hyperplasia in diffuse hyperinsulinemic hypoglycemia involves the constitutive activation of the mTOR pathway.5 The serine–threonine protein kinase mTOR has been implicated in the cellular response to nutrients and growth factor signaling.6 The mTOR pathway is
From the Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, Institute of Child Health, University College London (S.S., P.S., V.A., K.H.), and the Departments of Paediatric Endocrinology (S.S., P.S., V.A., K.H.) and Histopathology (D.P., M.A.), Great Ormond Street Hospital for Children, London, and the Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter (S.F., S.E.) — all in the United Kingdom; the Department of Pathology, University of California, San Francisco, San Francisco (S.A.); and the Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston (N.T., R.E.B.). Address reprint requests to Dr. Hussain at the Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, Institute of Child Health, University College London, 30 Guilford St., London WC1N 1EH, United Kingdom, or at [email protected]. N Engl J Med 2014;370:1131-7. DOI: 10.1056/NEJMoa1310967 Copyright © 2014 Massachusetts Medical Society.
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
1131
The
n e w e ng l a n d j o u r na l
of
m e dic i n e
abnormally activated in several neoplasms, including insulinoma,7 and inhibitors of mTOR have been increasingly recognized as a treatment option in patients with cancer.8 The use of the mTOR inhibitor sirolimus (formerly called rapamycin) in a patient with an insulinoma suggested a potential role for mTOR inhibitors in both the reduction of beta-cell proliferation and the inhibition of insulin production.9 In addition, therapy with everolimus, an mTOR kinase inhibitor, was reported to result in a clinically significant glycemic response and regression in tumor size in four patients with metastatic insulinoma.7 Given the potential role of the mTOR pathway in the pathogenesis of hyperinsulinemic hypoglycemia and the promising use of mTOR inhibitors in insulinoma, we studied the glycemic response to sirolimus in four consecutive patients with diffuse hyperinsulinemic hypoglycemia that had been unresponsive to diazoxide and octreotide.
maximal doses of diazoxide (20 mg per kilogram per day) and octreotide (35 μg per kilogram per day) were recruited to participate in the study. The characteristics of the patients are shown in Table 1. All the patients had severe symptomatic hypoglycemia (associated with seizures, poor feeding, and irritability) on day 1 of life in a local hospital, necessitating transfer to our center for further care. A central venous catheter was inserted, and high doses of dextrose and intra venous glucagon were administered to stabilize blood glucose levels at more than 63 mg per deciliter (3.5 mmol per liter). The diagnosis of hyperinsulinemic hypoglycemia was confirmed by means of standard testing (Table 2).10 Since there had not been a response to maximal doses of diazoxide and octreotide in any of the four patients, our standard protocol would have called for subtotal pancreatectomy for all of them. We therefore recruited these infants for our study. The study of the genetic mechanisms of hypo glycemia was approved by the research ethics Me thods committee at Great Ormond Street Hospital in Patients London. Approval for the study was also obFour consecutive patients with severe hyperinsu- tained from the drugs and therapeutics comlinemic hypoglycemia that was unresponsive to mittee at the hospital. Detailed discussions were
Table 1. Patient Characteristics and Assessment of Response to Treatment with Sirolimus.*
Patient No.
Sex
Birth Weight
Gestation
kg
wk
1
Female
2.38
2
Female
3
4
Age at Start of Sirolimus Treatment
Findings on 18F-DOPA–PET
Genetic Characteristics
Treatment at Study Entry
33
Diffuse
No mutation in ABCC8, KCNJ11, or HNF4A
11
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
4.71
40
Diffuse
Maternally inherited heterozygous ABCC8 mutation p.R74W (c.220C→T)
8
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
Male
4.50
39
Diffuse
Maternally inherited heterozygous ABCC8 mutation p.P1563T (c.4687C→A)
7
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
Male
3.04
37
Not performed
Homozygous ABCC8 mutation (c.1467+5G→A)
16
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
wk
* All intravenous fluids contained glucose to maintain normoglycemia. 18F-DOPA denotes fluorine-18-L-dihydroxyphenylalanine, and PET positron-emission tomography.
1132
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
brief report
held with the families, and the benefits and risks of the study protocol were explained, after which parents provided written informed consent. The protocol is available with the full text of this article at NEJM.org. Testing
Genomic DNA was extracted with the use of standard methods. The coding regions and conserved splice sites of ABCC8, KCNJ11, and HNF4A were amplified by means of a polymerase-chainreaction assay, and the products were sequenced on an ABI 3730 capillary sequencer (Applied Biosystems). If no mutation was identified, testing for a partial or whole gene deletion was performed by means of multiplex ligation-dependent probe amplification.11 We also tested for a recently identified deep intronic cryptic founder mutation in ABCC8.12 To confirm diffuse disease, scanning with fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron-emission tomography (PET) was performed in three of the four patients. The fourth patient had a homozygous ABCC8 mutation, which is strongly suggestive of diffuse disease; con sequently, 18F-DOPA–PET scanning was deemed unnecessary in this patient.
Dose of Intravenous Glucose at Study Entry
Response to Treatment with Sirolimus
Treatment
All the patients received sirolimus at an initial dose of 0.5 mg per square meter of body-surface area per day (in one or two doses). The dose was gradually increased with the goal of reaching a serum trough level of 5 to 15 ng per milliliter. The serum trough level of sirolimus was measured every 5 days. Once the desired serum drug level had been reached and blood glucose levels were stable, intravenous glucose and glucagon infusions were gradually tapered. Regular monitoring was performed, including a complete blood count, measurement of serum lipid levels, and analysis of renal and liver function. After discharge, patients were followed up regularly for assessment of glycemic control and measurement of serum sirolimus levels.
R e sult s Molecular Genetic Testing
Two infants had heterozygous maternally inherited ABCC8 mutations, p.R74W and p.P1563T. The p.R74W missense mutation has been reported in multiple patients.13 The p.P1563T mutation is novel and affects a conserved amino acid within the nucleotide binding domain 1 (NBD1) of the
Side Effects
Final Outcome
mg/kg/min 10
Day 15: Intravenous fluids discontinued Day 17: Glucagon discontinued Day 20: Octreotide discontinued
Mild elevation of triglyceride levels
Discharged home to have oral feedings every 4 hours
9
Day 10: Intravenous fluids discontinued Day 14: Glucagon discontinued Day 20: Octreotide discontinued
Transient elevation of liver aminotransferase levels
Discharged home to have oral feedings every 4 hours
9
Day 10: Intravenous fluids discontinued Day 12: Glucagon discontinued Day 19: Octreotide discontinued
Mild, transient elevation Discharged home to have onof cholesterol and demand oral feeding triglyceride levels
12
Day 16: Intravenous fluids discontinued Day 19: Glucagon discontinued and octreotide subcutaneous injections continued at 10 μg/kg/day
None
Discharged home to have gastrostomy feedings every 4 hours
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
1133
The
n e w e ng l a n d j o u r na l
of
m e dic i n e
Table 2. Clinical and Biochemical Data at Diagnosis, at Discharge, and at 24, 36, and 52 Weeks of Age.
Assessment
Age
Duration of Treatment with Sirolimus wk
Dose of Sirolimus
Duration of Fasting
Blood Glucose Level*
Insulin Level†
mg/day
hr
mg/dl
mU/liter
NEFA Level‡
3β-Hydroxybutyrate Level§
mmol/liter
Patient 1 Hypoglycemia screening at diagnosis Fasting results at discharge
3
0
n e w e ng l a n d j o u r na l
of
m e dic i n e
brief report
Sirolimus Therapy in Infants with Severe Hyperinsulinemic Hypoglycemia Senthil Senniappan, M.D., Sanda Alexandrescu, M.D., Nina Tatevian, M.D., Pratik Shah, M.D., Ved Arya, M.D., Sarah Flanagan, Ph.D., Sian Ellard, Ph.D., Dyanne Rampling, F.I.B.M.S., Michael Ashworth, M.D., Robert E. Brown, M.D., and Khalid Hussain, M.D.
SUM M A R Y Hyperinsulinemic hypoglycemia is the most common cause of severe, persistent neonatal hypoglycemia. The treatment of hyperinsulinemic hypoglycemia that is unresponsive to diazoxide is subtotal pancreatectomy. We examined the effectiveness of the mammalian target of rapamycin (mTOR) inhibitor sirolimus in four infants with severe hyperinsulinemic hypoglycemia that had been unresponsive to maximal doses of diazoxide (20 mg per kilogram of body weight per day) and octreotide (35 μg per kilogram per day). All the patients had a clear glycemic response to sirolimus, although one patient required a small dose of octreotide to maintain normoglycemia. There were no major adverse events during 1 year of follow-up.
H
yperinsulinemic hypoglycemia, a major cause of severe hypoglycemia during the neonatal period, is characterized by inappropriate insulin secretion from pancreatic beta cells in the presence of low blood glucose levels.1 The condition may result from defects in key genes involved in the regulation of insulin secretion from beta cells, including ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A, HNF1A, and UCP2.1,2 Two major histologic subtypes have been described: diffuse and focal.3 Mutations in ABCC8 and KCNJ11 are associated with severe hyperinsulinemic hypoglycemia that is unresponsive to medical treatment with diazoxide and octreo tide.1 The only treatment option currently available for patients with medically unresponsive forms of diffuse hyperinsulinemic hypoglycemia is a subtotal pancreatectomy, in which 95 to 98% of insulin-secreting cells are physically removed to alleviate the severe hypoglycemia. However, some patients who have undergone surgery continue to have recurrent hyperinsulinemic hypoglycemia, whereas diabetes mellitus and exocrine pancreatic insufficiency develop in others. In a recent study of 105 affected children who underwent pancreatectomy, 59% had persistent hyperinsulinemic hypoglycemia up to 5 years after surgery, and diabetes mellitus had developed in all the children by the time they reached early adolescence.4 Hence, there is a need for a medical therapy that can be used as an alternative to subtotal pancreatectomy. A possible mechanism of hyperinsulinism and beta-cell hyperplasia in diffuse hyperinsulinemic hypoglycemia involves the constitutive activation of the mTOR pathway.5 The serine–threonine protein kinase mTOR has been implicated in the cellular response to nutrients and growth factor signaling.6 The mTOR pathway is
From the Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, Institute of Child Health, University College London (S.S., P.S., V.A., K.H.), and the Departments of Paediatric Endocrinology (S.S., P.S., V.A., K.H.) and Histopathology (D.P., M.A.), Great Ormond Street Hospital for Children, London, and the Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter (S.F., S.E.) — all in the United Kingdom; the Department of Pathology, University of California, San Francisco, San Francisco (S.A.); and the Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston (N.T., R.E.B.). Address reprint requests to Dr. Hussain at the Developmental Endocrinology Research Group, Clinical and Molecular Genetics Unit, Institute of Child Health, University College London, 30 Guilford St., London WC1N 1EH, United Kingdom, or at [email protected]. N Engl J Med 2014;370:1131-7. DOI: 10.1056/NEJMoa1310967 Copyright © 2014 Massachusetts Medical Society.
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
1131
The
n e w e ng l a n d j o u r na l
of
m e dic i n e
abnormally activated in several neoplasms, including insulinoma,7 and inhibitors of mTOR have been increasingly recognized as a treatment option in patients with cancer.8 The use of the mTOR inhibitor sirolimus (formerly called rapamycin) in a patient with an insulinoma suggested a potential role for mTOR inhibitors in both the reduction of beta-cell proliferation and the inhibition of insulin production.9 In addition, therapy with everolimus, an mTOR kinase inhibitor, was reported to result in a clinically significant glycemic response and regression in tumor size in four patients with metastatic insulinoma.7 Given the potential role of the mTOR pathway in the pathogenesis of hyperinsulinemic hypoglycemia and the promising use of mTOR inhibitors in insulinoma, we studied the glycemic response to sirolimus in four consecutive patients with diffuse hyperinsulinemic hypoglycemia that had been unresponsive to diazoxide and octreotide.
maximal doses of diazoxide (20 mg per kilogram per day) and octreotide (35 μg per kilogram per day) were recruited to participate in the study. The characteristics of the patients are shown in Table 1. All the patients had severe symptomatic hypoglycemia (associated with seizures, poor feeding, and irritability) on day 1 of life in a local hospital, necessitating transfer to our center for further care. A central venous catheter was inserted, and high doses of dextrose and intra venous glucagon were administered to stabilize blood glucose levels at more than 63 mg per deciliter (3.5 mmol per liter). The diagnosis of hyperinsulinemic hypoglycemia was confirmed by means of standard testing (Table 2).10 Since there had not been a response to maximal doses of diazoxide and octreotide in any of the four patients, our standard protocol would have called for subtotal pancreatectomy for all of them. We therefore recruited these infants for our study. The study of the genetic mechanisms of hypo glycemia was approved by the research ethics Me thods committee at Great Ormond Street Hospital in Patients London. Approval for the study was also obFour consecutive patients with severe hyperinsu- tained from the drugs and therapeutics comlinemic hypoglycemia that was unresponsive to mittee at the hospital. Detailed discussions were
Table 1. Patient Characteristics and Assessment of Response to Treatment with Sirolimus.*
Patient No.
Sex
Birth Weight
Gestation
kg
wk
1
Female
2.38
2
Female
3
4
Age at Start of Sirolimus Treatment
Findings on 18F-DOPA–PET
Genetic Characteristics
Treatment at Study Entry
33
Diffuse
No mutation in ABCC8, KCNJ11, or HNF4A
11
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
4.71
40
Diffuse
Maternally inherited heterozygous ABCC8 mutation p.R74W (c.220C→T)
8
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
Male
4.50
39
Diffuse
Maternally inherited heterozygous ABCC8 mutation p.P1563T (c.4687C→A)
7
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
Male
3.04
37
Not performed
Homozygous ABCC8 mutation (c.1467+5G→A)
16
Octreotide, 35 μg/kg/day subcutaneously; glucagon, 5 μg/kg/hr intravenously
wk
* All intravenous fluids contained glucose to maintain normoglycemia. 18F-DOPA denotes fluorine-18-L-dihydroxyphenylalanine, and PET positron-emission tomography.
1132
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
brief report
held with the families, and the benefits and risks of the study protocol were explained, after which parents provided written informed consent. The protocol is available with the full text of this article at NEJM.org. Testing
Genomic DNA was extracted with the use of standard methods. The coding regions and conserved splice sites of ABCC8, KCNJ11, and HNF4A were amplified by means of a polymerase-chainreaction assay, and the products were sequenced on an ABI 3730 capillary sequencer (Applied Biosystems). If no mutation was identified, testing for a partial or whole gene deletion was performed by means of multiplex ligation-dependent probe amplification.11 We also tested for a recently identified deep intronic cryptic founder mutation in ABCC8.12 To confirm diffuse disease, scanning with fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron-emission tomography (PET) was performed in three of the four patients. The fourth patient had a homozygous ABCC8 mutation, which is strongly suggestive of diffuse disease; con sequently, 18F-DOPA–PET scanning was deemed unnecessary in this patient.
Dose of Intravenous Glucose at Study Entry
Response to Treatment with Sirolimus
Treatment
All the patients received sirolimus at an initial dose of 0.5 mg per square meter of body-surface area per day (in one or two doses). The dose was gradually increased with the goal of reaching a serum trough level of 5 to 15 ng per milliliter. The serum trough level of sirolimus was measured every 5 days. Once the desired serum drug level had been reached and blood glucose levels were stable, intravenous glucose and glucagon infusions were gradually tapered. Regular monitoring was performed, including a complete blood count, measurement of serum lipid levels, and analysis of renal and liver function. After discharge, patients were followed up regularly for assessment of glycemic control and measurement of serum sirolimus levels.
R e sult s Molecular Genetic Testing
Two infants had heterozygous maternally inherited ABCC8 mutations, p.R74W and p.P1563T. The p.R74W missense mutation has been reported in multiple patients.13 The p.P1563T mutation is novel and affects a conserved amino acid within the nucleotide binding domain 1 (NBD1) of the
Side Effects
Final Outcome
mg/kg/min 10
Day 15: Intravenous fluids discontinued Day 17: Glucagon discontinued Day 20: Octreotide discontinued
Mild elevation of triglyceride levels
Discharged home to have oral feedings every 4 hours
9
Day 10: Intravenous fluids discontinued Day 14: Glucagon discontinued Day 20: Octreotide discontinued
Transient elevation of liver aminotransferase levels
Discharged home to have oral feedings every 4 hours
9
Day 10: Intravenous fluids discontinued Day 12: Glucagon discontinued Day 19: Octreotide discontinued
Mild, transient elevation Discharged home to have onof cholesterol and demand oral feeding triglyceride levels
12
Day 16: Intravenous fluids discontinued Day 19: Glucagon discontinued and octreotide subcutaneous injections continued at 10 μg/kg/day
None
Discharged home to have gastrostomy feedings every 4 hours
n engl j med 370;12 nejm.org march 20, 2014
The New England Journal of Medicine Downloaded from nejm.org on May 5, 2014. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
1133
The
n e w e ng l a n d j o u r na l
of
m e dic i n e
Table 2. Clinical and Biochemical Data at Diagnosis, at Discharge, and at 24, 36, and 52 Weeks of Age.
Assessment
Age
Duration of Treatment with Sirolimus wk
Dose of Sirolimus
Duration of Fasting
Blood Glucose Level*
Insulin Level†
mg/day
hr
mg/dl
mU/liter
NEFA Level‡
3β-Hydroxybutyrate Level§
mmol/liter
Patient 1 Hypoglycemia screening at diagnosis Fasting results at discharge
3
0
