Ga-68/Lu-177 octreotate theranostic paradigm in metastatic Merkel cell carcinoma

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Introduction: Merkel cell carcinoma (MCC) is a rare, aggressive, cutaneous neuroendocrine tumor with poor survival and significant propensity for metastasising. MCC is normally characterised by an up-regulation of somatostatin receptors (SSTR) which introduces the possibility for a targeted treatment approach using peptide receptor radionuclide therapy (PRRT).

Aim(s): Two case studies are discussed in support of PRRT and multimodality treatment approaches as a therapeutic option in the management of MCC.

Materials and methods: SSTR avidity was confirmed by Ga-68 octreotate PET imaging in two patients with metastatic MCC (Patient 1 and Patient 2). Multimodality treatment approaches including pembrolizumab immunotherapy, capecitabine, temozolomide and PRRT (Lu-177 and Ac-225 octreotate) in combination with lanreotide were utilised. In the case of one patient (Patient 2), liver-directed Y-90 SIRT was also utilised. Serial monitoring with CT, FDG PET and Ga-68 octreotate PET together with clinical review was performed to monitor treatment response and to direct therapy.

Conference: 18th Annual ENETS Concerence (2021)

Presenting Author: Lenzo N

Authors: Falzone N, Meyrick D, Lee B, Lenzo N,

Keywords: peptide receptor radionuclide therapy, Merkel cell carcinoma, Lu-177 octreotate, Ac-225 octreotate,