DPP-4 INHIBITOR THERAPY IN PATIENTS AFTER PANCREATIC TRANSPLANT.

OBJECTIVE: Management of new onset hyperglycemia after pancreas transplantation (PT) is not well studied. There is a lack of information on effective and safe management options for hyperglycemia after PT. We tested the hypothesis that early intervention for hyperglycemia using a dipeptidyl peptidase-4 (DPP-4) inhibitor prolongs insulin-free graft function in patients after PT. METHODS: Twenty-six patients who developed noninsulin-dependent hyperglycemia at least 1 year after PT met the inclusion criteria for this retrospective chart review. Sitagliptin, a DPP-4 inhibitor, was a commonly used therapy for hyperglycemia after PT due to its wide availability and coverage. The standard therapy group included patients who did not receive any oral or noninsulin injection therapy until insulin was clearly required to control hyperglycemia. The intervention group included patients who had received sitagliptin soon after hyperglycemia developed. The median follow-up period was 45 months. The time to hyperglycemia from 1 year after PT and time to insulin requirement after hyperglycemia development were compared between these 2 groups. RESULTS: The time to hyperglycemia after PT was not different between the groups, but the time to insulin requirement was significantly longer in the intervention group compared with the standard therapy group (P<.001). After adjusting for body mass index (BMI), the difference remained significant (P<.001). CONCLUSION: Early treatment of hyperglycemia after PT with a DPP-4 inhibitor such as sitagliptin prolongs the time to insulin therapy compared with a standard observation approach. Prospective studies are needed to further investigate this observation.

Medullary thyroid carcinoma.

PURPOSE OF REVIEW: To summarize recent developments in the diagnosis and management of patients with medullary thyroid cancer (MTC), with a focus on pathogenesis, systemic therapy, and future directions. RECENT FINDINGS: The addition of mutational analysis to cytological assessment of thyroid nodules has improved the diagnostic accuracy of MTC. The discovery of new genomic alterations and overexpression of certain factors allows for improved prognostication in MTC and provides potentially new therapeutic agents. New data suggest that tumor environment may be more immunogenic than previously thought in a subset of MTCs with identification of a new MTC-specific antigen leading to a revival of investigating immune-based therapy for this disease. The newly approved selective rearranged during transfection (RET0-inhibitors, selpercatinib and pralsetinib, offer promising results, and tolerability for patients with RET-mutated MTC; however, the development of resistance mechanisms may be problematic. SUMMARY: MTC has witnessed remarkable advancements in recent years. Our new understanding of some of the driver mutations in MTC allows for therapeutics with more tolerable adverse event profiles. However, there is still a need for more effective treatment strategies for subsets of patients without actionable mutations and for those who develop resistance to currently available therapies.

A Homozygous RET K666N Genotype With an MEN2A Phenotype.

Context: Germline RET K666N mutation has been described as a pathogenic mutation with low disease penetrance for medullary thyroid cancer (MTC) without other features of multiple endocrine neoplasia type 2A. We describe a patient with homozygous RET K666N mutation with MTC and bilateral pheochromocytoma (PHEO). Case Description: A 59-year-old woman received a diagnosis of MTC after biopsy of two thyroid nodules. Coincident biochemical and radiologic testing was suspicious for bilateral PHEO, confirmed after bilateral adrenalectomy. There was no evidence of primary hyperparathyroidism (PHPT). She had a total thyroidectomy with neck dissection revealing bilateral MTC with lymph node metastases. Germline RET testing identified homozygous K666N mutations. Genetic testing of family members showed that both adult children harbor a heterozygous K666N mutation. Her 32-year-old son had an elevated calcitonin level and underwent thyroidectomy, which identified MTC. Her 30-year-old daughter had a normal calcitonin level. Prophylactic thyroidectomy showed C-cell hyperplasia only. Three of seven other family members were tested and found to carry the mutation. All had normal calcitonin levels, and none had biochemical evidence of PHEO or PHPT. Given the absence of PHEO in reported RET K666N families, our proband underwent genetic testing for causes of hereditary paragangliomas or PHEO. No additional mutations were identified. Conclusions: Here we report a case of a homozygous RET K666N mutation leading to coincident MTC and PHEO. Heterozygous presentations of RET K666N mutations have low penetrance for isolated MTC. We believe that the gene dosage associated with the homozygosity of this variant contributed to the occurrence of bilateral PHEO.

Targeted Therapy in Advanced Thyroid Cancer to Resensitize Tumors to Radioactive Iodine.

Context: Many differentiated thyroid cancers (DTC) dedifferentiate and become radioactive iodine (RAI)-refractory (RAIR) with worse outcomes. Targeted therapy (TTx) may downregulate MAPK signaling and sensitize tumors to RAI. Objective: We describe patients with RAIR DTC receiving TTx with demonstrated RAI uptake allowing for iodine-131 (I131) administration. Design: Charts of patients with metastatic, progressive, RAIR DTC in whom TTx increased RAI uptake on a diagnostic whole-body scan (WBS), were reviewed. Results of WBS, I131 administration, thyroglobulin (TG) panels, and cross-sectional studies were recorded. Setting: Thirteen patients [median age (range), 56 (45 to 75) years; seven men] were included; 11 (85%) had DTC, two (15%) had poorly DTC. Nine (69%) had BRAF mutations, three (23%) had RAS mutations, and one (8%) was wild type. Selective BRAF or an MEK inhibitor TTx was continued for a median (range) of 14.3 (1 to 76.4) months before diagnostic WBS. Results: Nine (69%) patients were treated with I131 [median (range) activity, 204.4 (150 to 253) mCi], after which TTx was discontinued. Median (range) follow-up was 8.3 (0 to 17.4) months after I131 therapy. All nine patients had durable disease control (three had partial response, six had stable disease). TG and TG antibody levels increased in patients who demonstrated uptake before TTx, and declined in eight of the nine patients after I131 treatment. Adverse events included pneumonitis and sialadenitis. Conclusion: TTx in BRAF-/RAS-mutated RAIR DTC resensitizes tumors to iodine. Subsequent I131 administration results in meaningful responses. Patient selection, adverse events, response duration, and survival impact require additional study.