An easy blood draw can provide physicians with helpful information that may determine if peptide receptor radionuclide therapy (PRRT) is more likely to be effective in a patient with neuroendocrine cancer. The blood-based biomarker PPQ can predict which patients will reply to PRRT with 96 percent accuracy; changes in one other biomarker, NETest, accurately correlate with PRRT response in 90 percent of patients. The study, published within the April issue of The Journal of Nuclear Medicine, opens recent possibilities of tailoring radiopharmaceutical treatment to patients.

While biomarkers have been used to predict the outcomes of treatments for breast, prostate, and other cancers, there are currently no objective means to predict the efficacy of radiopharmaceutical therapy for neuroendocrine tumors. “In previous studies our team introduced the blood-based biomarkers PPQ and NETest as a measure for determining whether treatment with PRRT would achieve success,” noted Lisa Bodei, MD, PhD, nuclear medicine physician at Memorial Sloan Kettering Cancer Center in Recent York, Recent York. “On this recent study we sought to validate the role of PPQ and NETest in predicting response and monitoring PRRT.”

Sixty-seven patients with somatostatin receptor-positive gastroenteropancreatic and lung neuroendocrine tumors were included within the study. All patients had metastatic disease and had received prior treatments. Blood samples were collected before each cycle of PRRT and at follow-up. PPQ was scored as either positive (more likely to respond) or negative (unlikely to reply), and NETest was measured on a scale of zero to 100, with the upper limit of normality being 20.

Of the 67 patients within the study, 40 were classified as PPQ+, and 39 of them (98 percent) responded to PRRT. Twenty-seven patients were PPQ–, and 25 patients on this group experienced disease progression despite PRRT. The general predictive accuracy of PPQ was 96 percent.

NETest was elevated in all patients prior to PRRT therapy. For PRRT responders, baseline NETest levels were 67, which decreased by 37 percent after treatment. For non-responders, baseline NETest levels were 44, which increased by 76 percent at follow-up. The NETest biomarker was 90 percent accurate for determining PRRT response.

The outcomes of this study reveal that not all tumors are created equal; some are more susceptible to reply to PRRT, and a few are less liable to radiopharmaceutical therapy. That is the rationale why our research is vital: to grasp from the beginning which patients would require an intensified treatment plan and which patients, as an alternative, can profit from a lighter regimen will tremendously improve their management.”

Lisa Bodei, MD, PhD, nuclear medicine physician, Memorial Sloan Kettering Cancer Center

This study was made available online in November 2022.

Source:

Society of Nuclear Medicine and Molecular Imaging

Journal reference:

Bodei, L., et al. (2022). Interim Evaluation of a Prospective Validation of two Blood-Based Genomic Assessments (PPQ and NETest) to Determine the Clinical Efficacy of 177Lu-DOTATATE in Neuroendocrine Tumors. Journal of Nuclear Medicine. doi.org/10.2967/jnumed.122.264363.