Somatostain receptor (SSTR)-targeted therapy in pulmonary large-cell neuroendocrine carcinoma (LCNEC) patients with intermediate proliferation rate (PR).

Abstract

e17509 Background: LCNEC is classified as a high-grade (HG) foregut-derived neuroendocrine tumor (NET), exceeded only by small-cell lung carcinoma (SCLC) in terms of aggressiveness. It is a recent disease entity, only two decades old, and uncommon: 2%-3% of all lung cancer cases. Therefore, therapy guidelines are still evolving. Methods: A single institution observational study, consecutive series. Histopathology diagnosis conformed to WHO criteria for thoracic tumors (Travis et al, IARC Press, 2004). Immunohistochemistry included proliferation Ki67 index evaluation. SSTRs' affinity was assessed either by 111 In octreotate SPECT, or by Ga68 DOTA-NOC octreotate PET CT total body scans. Results: We have treated nine metastatic LCNEC patients over the last four years. Seven were scanned for presence of somatostatin receptors; 4 were positive. Three of the four had Ki67 staining ranging 10-20% (intermediate PR, IPR), one had 80% (high PR). All four have received octreotide LAR as a therapy component. In two cases octreotide was given upfront and conferred PFS of 18 and 8 months and, in the former- regression of hepatic lesions. The other patient also received 177 Lutetium radionuclide therapy (PRRT) upon progression, resulting in uptake normalization at an hepatic mass and stabilization of other lesions. The 3rd patient had started with induction chemotherapy and then maintained imaging-confirmed stable disease and normal function, during octreotide treatment, for three years. The fourth, HG patient, survived only 8 months. Three of the 9 patients are alive with disease on treatment, surviving 25+, 57+ and one, with 50% proliferation index and a negative DOTANOC scan, has survived 16+ months, with no targeted therapy. Conclusions: This small series illustrates the diagnostic value and therapeutic implication of SSTR scans, combined with Ki67 assessment, aiming at therapy selection for IPR subgroup, receptor positive, pulmonary LCNEC patients who can benefit from octreotide targeted therapy.