Introduction: 177Lu-DOTATATE-based peptide receptor radionuclide therapy (PRRT) is a promising therapy for metastatic and/ inoperable pheochromocytoma and paraganglioma (PPGL). We aim to evaluate the efficacy and safety of and identify predictors of response to 177Lu-DOTATATE therapy in metastatic and/ inoperable PPGL.
Methods: This retrospective study involved 15 patients of metastatic or unresectable PPGL, who received 177Lu-DOTATATE PRRT therapy. Clinical, biochemical (Plasma free normetanephrine), and radiological (anatomical and functional) responses were compared before and after the last therapy.
Results: A total of 15 patients PCC (4), sPGL (4), HNPGL (5), PCC+sPGL (1), HNPGL+sPGL (1) were included. The median duration of follow up was 27 (range: 11-62) months from the start of PRRT. Based on the RECIST (1.1) criteria, progressive disease was seen in three (20%), stable disease in eight (53 %), partial response in one (7%), and minor response in three (20%) and controlled disease in 12 (80%). On linear regression analysis presence of PGL (p= 0.044) and baseline SUVmax >21 (p < 0.0001) were significant positive predictors of early response to PRRT. Encouraging safety profiles were noted with no long term nephrotoxicity and haematotoxicity.
Conclusion: 177Lu-DOTATATE therapy is an effective and safe modality of treatment for patients with metastatic/inoperable PPGL. Although it is not prudent to withhold PRRT in metastatic PPGL with baseline SUVmax < 21, baseline SUVmax >21 can be used to predict early response to PRRT.