Simple Blood Test Predicts Neuroendocrine Tumor Response to Radiopharmaceutical Therapy

Biomarkers have been employed to forecast treatment outcomes for breast, prostate, and other types of cancer, although no objective methods currently exist for predicting the success of radiopharmaceutical therapy for neuroendocrine tumors. Now, a new study has revealed that a simple blood test can supply doctors with crucial information to ascertain if peptide receptor radionuclide therapy (PRRT) is likely to be effective in patients with neuroendocrine cancer. The blood-based biomarker PPQ can accurately predict PRRT responsiveness in 96% of patients, and changes in another biomarker, NETest, correlate with PRRT response in 90% of cases.

Previously, a group of nuclear medicine physicians at Memorial Sloan Kettering Cancer Center (MSK, New York, NY, USA) had introduced the blood-based biomarkers PPQ and NETest as indicators for the success of PRRT treatment. In this new study, the team aimed to validate the significance of PPQ and NETest in predicting and monitoring PRRT response. The new study included 67 patients with somatostatin receptor-positive gastroenteropancreatic and lung neuroendocrine tumors, all of whom had metastatic disease and prior treatments. The participants submitted blood samples before each PRRT cycle and during follow-up. PPQ was scored as either positive (likely to respond) or negative (unlikely to respond), while NETest was measured on a scale of zero to 100, with 20 being the upper limit of normality.

Of the 67 patients, 40 were classified as PPQ+ and 39 of them (98%) responded to PRRT. Among the 27 PPQ- patients, 25 experienced disease progression despite PRRT. The overall predictive accuracy of PPQ was 96%. Prior to PRRT therapy, all patients exhibited elevated NETest levels. In PRRT responders, baseline NETest levels were 67, decreasing by 37% after treatment. For non-responders, baseline NETest levels were 44, which rose by 76% during follow-up. NETest's accuracy in determining PRRT response was 90%.

“The results of this study demonstrate that not all tumors are created equal; some are more prone to respond to PRRT, and some are less susceptible to radiopharmaceutical therapy,” said Lisa Bodei, MD, PhD, nuclear medicine physician at Memorial Sloan Kettering Cancer Center. “This is the reason why our research is important: to understand from the start which patients will require an intensified treatment plan and which patients, instead, can benefit from a lighter regimen will tremendously improve their management.”

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