Oral Presentation 5th International Symposium on Phaeochromocytoma and Paraganglioma 2017

PRRT for PPGLS (#47)

Rod Hicks 1
  1. Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia

Despite being rare tumours, phaeochromocytoma (PCC) and paraganglioma (PGL) have an unexpectedly diverse genomic landscape. Some genomic subtypes can be associated a high risk of metastatic disease. Whether benign or malignant, secretion of catecholamines can lead to symptoms of sympathetic over-activity and, in some cases, life-threatening acute hypertensive crisis with end-organ damage and death. This is a complex disease genotype may influence clinical behaviour and prognosis. Treatment options for metastatic or unresectable primary disease are limited with low response rates to chemotherapy and targeted therapies. 131I- MIBG has long been a palliative therapy for tumours demonstrating high uptake. Studies suggest modest effectiveness in disease stabilisation or partial responses in >50%, and improvement of blood pressure but many are unsuitable for treatment, which is also logistically challenging. Another potential novel molecular target for PCC/PGL is over-expression of somatostatin receptors (SSTR). 68Ga-labelled-peptides bind to SSTR with high affinity enabling high sensitivity imaging with PET/CT, particularly in SDHX, a subgroup with increased malignant potential. The presence of SSTR also allows theranostic application and targeting with peptide receptor radionuclide therapy (PRRT) as a novel treatment approach.  There are limited published data on the outcomes of PRRT in PGL/PCC. Preliminary reports have suggested low toxicity and favourable efficacy in disease control. Our own experience suggests that this is an effective and well-tolerated option in appropriately selected patients and can be considered as a complementary treatment modality for both controlling catecholamine-related symptoms and disease progression. It is, however, a relatively complex therapy that requires an experienced multidisciplinary team. Catecholamine flare and the potential for renal disease to complicate treatment need to be anticipated and managed. Emerging options include combination of PRRT with radiosensitizing chemotherapy.