1590 - Longitudinal Increase in Ki67 and High-grade Transformation in Pancreatic Neuroendocrine Tumors (PNETs)

Background

Tumor proliferation and grade are important prognostic factors at diagnosis of PNETs. Little is known about how these factors change over time and if longitudinal increase in Ki67-index is associated with prognosis. The purpose of this work was to describe longitudinal changes in Ki67-index and tumor grade, as well as its impact on overall survival, in PNETs.

Methods

Platelet free plasma from 68 GEP-NET patients was collected. Whole miRNOME NGS analysis was performed on exome enriched small-RNAs fraction of 24 patients: 12 ¹⁸PET/FDG+ and 12 ¹⁸PET/FDG-. MiRNAs significantly associated with ¹⁸PET/FDG outcome has been identified and validated by RT/qPCR on overall case series. Target miRNAs fold enrichment were then combined to create predictors (pAB, pAC, pBC and pABC). Man-Whitney test was applied and validated target miRNAs had been correlated with clinical outcome and clinical parameters (ki-67, grading, tumor burden and ⁶⁸Gallium-PET SUV_max).

Results

NGS whole miRNOME analysis revealed 10 target miRNAs able to distinguish ¹⁸FDG/PET positive from negative Pancreatic-NETs (PNETs). Subsequently, mir-A, mir-B, mir-C (patent pending) have been validated on overall case series by multiplex RT/qPCR (p < 0,0047 and p < 0,0001, respectively), on PNETs case series and pBC and pABC resulted to be the best predictors (p < 0,0001). All validated miRNAs and derived predictors, especially mir-B, result significantly increased in small intestine (SINETs) and in PNETs patients when compared to healthy controls. Correlation analysis between target miRNAs and clinical parameters also revealed that mir-B negatively correlates with ⁶⁸Ga-PET SUV_max (p < 0,04), suggesting interference with SSTR expression.

Conclusions

We defined a 3 miRNAs signature able to correlate with ¹⁸FDG/PET status. Over expression of mir-A, mir-B, mir-C or combined predictors in PNETs can provide prognostic information on tumor aggressiveness and might help to identify PRRT non-responders. In addition mir-B negatively correlates with clinical outcome and ⁶⁸Ga-PET SUV_max. We are investigating if mirB interfere with SSTR expression, affecting PRRT efficacy.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Uppsala University.

Funding

European Neuroendocrine Tumor Society, Uppsala University.

Disclosure

J. Botling: Honoraria (self): Novartis. A. Lamarca: Honoraria (self): Merck; Honoraria (self): Pfizer; Honoraria (self): Ipsen; Advisory / Consultancy: EISAI; Advisory / Consultancy: Nutricia; Travel / Accommodation / Expenses: Ipsen; Travel / Accommodation / Expenses: Pfizer; Travel / Accommodation / Expenses: Bayer; Travel / Accommodation / Expenses: AAA; Travel / Accommodation / Expenses: SirtEx; Travel / Accommodation / Expenses: Novartis; Travel / Accommodation / Expenses: Mylan; Travel / Accommodation / Expenses: Delcath. G. Rindi: Honoraria (self): Novartis; Honoraria (self): Ipsen. J. Crona: Honoraria (self): Novartis; Honoraria (self): Ipsen. All other authors have declared no conflicts of interest.