<SUP>177</SUP>Lu-DOTATATE Peptide Receptor Radionuclide Therapy (PRRT) in Metastatic/inoperable phaeochromocytomas and paragangliomas and focus on the impact of genetic variations in SDHx mutation on treatment outcomes - A single centre retrospective analysis of experience at an ENETS Centre of Excellence

Shekhda Kalyan Mansukhbhai; Eleni Armeni; Aimee Hayes; Shaunak Navalkissoor; Dalvinder Mandair; Yiwang Xu; Dominic Yu; Ann-Marie Quigley; Gopinath Gnanasegaran; Christos Toumpanakis; Martyn Caplin; Bernard Khoo

doi:10.1530/endoabs.94.OC2.2

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Endocrine Abstracts (2023) 94 OC2.2 | DOI: 10.1530/endoabs.94.OC2.2

SFEBES2023 Oral Communications Endocrine Cancer and Late Effects (6 abstracts)

¹⁷⁷Lu-DOTATATE Peptide Receptor Radionuclide Therapy (PRRT) in Metastatic/inoperable phaeochromocytomas and paragangliomas and focus on the impact of genetic variations in SDHx mutation on treatment outcomes – A single centre retrospective analysis of experience at an ENETS Centre of Excellence

Kalyan Mansukhbhai Shekhda , Eleni Armeni , Aimee Hayes , Shaunak Navalkissoor , Dalvinder Mandair , Yiwang Xu , Dominic Yu , Ann-Marie Quigley , Gopinath Gnanasegaran , Christos Toumpanakis , Martyn Caplin & Bernard Khoo

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Royal Free Hospital, London, United Kingdom

Introduction: Metastatic phaeochromocytomas (PCC) and paragangliomas (PGL), collectively known as metastatic PPGL (mPPGL), represent uncommon neuroendocrine tumours for which no standardized treatment guidelines exist. The emerging therapeutic modality employing ¹⁷⁷Lu-DOTATATE Peptide Receptor Radionuclide Therapy (PRRT) has exhibited favourable tolerability in the management of these patients.

Methods: In this retrospective analysis, we investigated the efficacy and safety of PRRT in mPPGL and explored the influence of germline pathogenic variations in Succinate Dehydrogenase (SDHx) subunit-encoding genes on treatment outcomes. Nineteen patients with mPPGL who received 2 or more cycles of ¹⁷⁷Lu-DOTATATE therapy were included. Clinical, radiological and biochemical responses were assessed 8-12 weeks after the final PRRT cycle, and comparative analysis was conducted to evaluate the effects of PRRT therapy on various parameters between the SDHx-positive and SDHx-negative groups. Progression-free survival was estimated using Kaplan-Meier survival analysis.

Results: The median follow-up duration from cycle 1 of PRRT was 29 months (range: 5-114 months). Post-treatment radiological evaluation confirmed stable disease in 10 patients (53%), partial response in 1 patient (5%), and progressive disease in 8 patients (42%). The overall median PFS for the entire cohort, PGL patients, SDHx-positive cohort, SDHx-negative cohort from the initiation of PRRT was 15 (95% CI, 6.16-23.84), 15 (0.00 – 40.88), 13 (0.00 – 27.32), and 18 (95% CI, 0.00 – 53.28) months respectively. Overall survival for the total study cohort and median PFS for PCC could not be assessed. No CTCAE grade 3-4 cytopenia or nephrotoxicity were observed.

Conclusion: This study provides evidence supporting effectiveness of PRRT in patients with mPPGL as it demonstrates promising outcomes in terms of PFS and minimal occurrence of severe adverse effects. However, further prospective, randomised and controlled studies are necessary to validate these findings.