The Journal of Nuclear Medicine

Radiopharmaceutical Therapy in Metastatic Insulinomas Controls Symptoms, Reduces Medications

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New research published in the The Journal of Nuclear Medicine demonstrates that peptide receptor radionuclide therapy (PRRT) is effective for clinical control of symptomatic metastatic insulinomas. In the largest study to date of metastatic insulinoma patients treated with PRRT, more than 80% of patients had long-lasting symptom control, and nearly 60% were able to reduce the use of other drugs to treat the disease. 

Metastatic insulinoma is a rare malignant neuroendocrine tumor characterized by inappropriate insulin secretion. This results in life-threatening hypoglycemia, which is often difficult to treat. The severity of symptoms can range from mild to life-threatening hypoglycemic events, leading to coma and death. Most insulinomas are benign, but approximately 6% develop metastases and are therefore considered malignant.

“Because of the rarity of the disease, the treatment strategies for malignant metastatic disease are ill-defined,” stated Damian Wild, MD, PhD, nuclear medicine physician at University Hospital Basel, in Basel, Switzerland. “There is currently limited data available about the efficacy of PRRT in patients with malignant insulinomas. Our research aimed to evaluate whether PRRT could improve symptoms and if it had an impact on medication needed to control hypoglycemia.”

The retrospective study included 26 patients with malignant insulinomas who were treated with a total of 106 cycles of 90Y-DOTATOC or 177Lu-DOTATOC. A scoring system was used to quantify the severity and frequency of hypoglycemic episodes, and the score before and after PRRT was analyzed. Information on medication needed to control hypoglycemia before and after PRRT was also collected, an overall and progression-free survival was recorded.

PRRT was effective in controlling hypoglycemia in 81% of the study population and enabled 58% of patients to reduce the use of other drugs to control hypoglycemic episodes, resulting in reduced potential drug side effects. Overall and progression-free survival were 19.7 and 11.7 months, respectively.

“Compared to the effectiveness of other drugs commonly used to control hypoglycemia, the results of PRRT are promising and will likely have an impact on guidelines for the treatment of metastatic insulinoma,” noted Wild. “They also imply that PRRT is indicated at an earlier time point, for example as a first or second line of therapy, for the treatment of metastatic insulinomas.”

Novel PET Imaging Technique Accurately Diagnoses Adrenal Gland Disorder.

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A novel imaging approach, 68Ga-pentixafor PET/CT, has been shown to accurately identify sub-types of primary aldosteronism, an adrenal gland disorder, outperforming conventional methods for diagnosis. Reported in The Journal of Nuclear Medicine, this detailed imaging technique provides a clearer picture of the adrenal glands, helping doctors decide more confidently whether surgery is the right option for patients.

Primary aldosteronism is an endocrine disorder that occurs when the adrenal glands produce too much of the hormone aldosterone, frequently caused by the presence of nodules on the glands. High aldosterone levels cause the body to retain too much sodium and not enough potassium. This imbalance can lead to high blood pressure, putting patients at an increased risk of stroke and heart disease.

“In primary aldosteronism, it’s important for physicians to differentiate between surgically eligible and ineligible forms so that they can develop the best treatment plan. This is usually done with adrenal CT and adrenal venous sampling. However, is rather challenging and often imprecise to diagnose adrenal micronodules with these methods,” said Li Huo, MD, PhD, professor and chair in the Department of Nuclear Medicine at the Chinese Academy of Medical Sciences and Peking Union Medical College Hospital in Beijing, China. “To more clearly image these micronodules, we combined PET/CT with a unique tracer that targets specific receptors in the adrenal glands and evaluated its performance.”

In the study, 123 patients with adrenal micronodules identified by adrenal CT were examined using 68Ga-pentixafor PET/CT, and 104 patients who underwent surgery or successful adrenal venous sampling were included in the analysis. Nuclear medicine physicians evaluated the 68Ga-pentixafor PET/CT data for sensitivity, specificity and accuracy of visual analysis. This information was then compared to adrenal CT and adrenal venous sampling results.

68Ga-pentixafor PET/CT showed superior sensitivity, specificity and accuracy (90.2 percent, 72.7 percent and 86.5 percent, respectively) in identifying surgically eligible primary aldosteronism patients compared with adrenal CT (73.1 percent, 53.8 percent and 68.3 percent, respectively). It was also able to predict surgical outcomes better than adrenal venous sampling (82.4 percent vs. 68.86 percent).

“The significance of this work lies in its potential to change how we diagnose and treat primary aldosteronism patients with tiny adrenal nodules. For patients, this means an improved chance of getting the right treatment, especially when it comes to deciding whether surgery is necessary. Accurate diagnosis is crucial because it leads to more effective treatments, less unnecessary surgery and overall better health outcomes. It’s about offering patients a more personalized and precise medical approach,” stated Huo.