PRRT may improve survival in metastatic paraganglioma, pheochromocytoma
Use of peptide receptor radionuclide therapy (PRRT) results in valuable clinical and biochemical responses with low toxicity and encouraging survival in unresectable paraganglioma (PGL)/pheochromocytoma (PCC), suggests a recent study.
Researchers retrospectively examined 20 consecutive patients (aged 21 to 77 years; 13 men) with high somatostatin receptor (SSTR) expression treated with 177Lu-DOTA-octreotate, including nine who received radiosensitizing chemotherapy. There was a median 22 GBg (median 4 cycles) cumulative activity. They examined PPRT outcomes in these patients from two referral centres.
A total of 14 patients received treatment for uncontrolled hypertension and six for progressive or symptomatic metastatic disease or local recurrence.
Three months following PRRT, eight of 14 patients treated for hypertension needed lesser medication doses; five showed no change in antihypertension doses; and one was lost to follow-up. Of the patients, 86 percent had serum chromogranin-A reduction.
Thirty-six percent of the entire cohort had disease regression (29 percent partial and 7 percent minor response) on computed tomography, with stable results in 50 percent. There were three patients with bony disease evaluable only on SSTR imaging (2 partial response and 1 stable).
There was a median 39 months of progression-free survival, but median overall survival was not achieved (5 deaths; median follow-up, 28 months) in the study. Four patients presented with grade 3 lymphopaenia, and two had grade 3 thrombocytopaenia. In addition, two patients had renal impairment, which was mainly driven by underlying disease processes.
“Because PRRT has logistic and radiation-safety advantages compared to 131I-MIBG therapy, further prospective evaluation is warranted,” researchers said.