Data from Tumor Growth Rate as a Validated Early Radiological Biomarker Able to Reflect Treatment-Induced Changes in Neuroendocrine Tumors: The GREPONET-2 Study

Maxime Ronot,Philip Borg,Pavan Najran,Daniela Pezzutti,Joakim Crona,Louis De Mestier,Niklaus Scaefer,Marianne Pavel,Angela Lamarca,Clarisse Dromain,Frederico Costa,Salma Moalla,Luciana Carvhalo,Régis Otaviano França Bezerra ,Anders Sundín ,Carlos López López ,Naïk Vietti Violi ,Marta Opalińska ,Éric Baudin ,Héctor Vidal Trueba

doi:10.1158/1078-0432.c.6527771

Abstract

<div>AbstractPurpose:Tumor growth rate (TGR) represents the percentage change in tumor volume per month (%/m). Previous results from the GREPONET study showed that TGR measured after 3 months (TGR3m) of starting systemic treatment (ST) or watch and wait (WW) was an early biomarker predicting progression-free survival (PFS) in neuroendocrine tumors (NET).Experimental Design:Patients from 7 centers with advanced grade (G) 1/2 NETs from the pancreas (P)/small bowel (SB) initiating ST/WW were eligible. Computed tomography (CT)/MRI performed at prebaseline, baseline, and 3(±1) months of study entry were retrospectively reviewed. Aim-1: explore treatment-induced changes in TGR (ΔTGR3m-BL; paired T test), and Aim-2: validate TGR3m (<0.8%/m vs. ≥0.8%/m) as an early biomarker in an independent cohort (Kaplan–Meier/Cox regression).Results:Of 785 patients screened, 127 were eligible. Mean (SD) TGR0 and TGR3m were 5.4%/m (14.9) and −1.4%/m (11.8), respectively. Mean (SD) ΔTGR3m-BL paired-difference was −6.8%/m (19.3; P < 0.001). Most marked ΔTGR3m-BL [mean (SD)] were identified with targeted therapies [−11.3%/m (4.7); P = 0.0237] and chemotherapy [−7.9%/m (3.4); P = 0.0261]. Multivariable analysis confirmed the absence of previous treatment (OR = 4.65; 95% CI, 1.31–16.52; P = 0.018) and low TGR3m (continuous variable; OR 1.09; 95% CI, 1.01–1.19; P = 0.042) to be independent predictors of radiologic objective response. When the multivariable survival analysis for PFS (Cox regression) was adjusted to grade (P = 0.004) and stage (P = 0.017), TGR3m ≥ 0.8 (vs. <0.8) maintained its significance as a prognostic factor (P < 0.001), whereas TGR0 and ΔTGR3m-BL did not. TGR3m ≥ 0.8%/m was confirmed as an independent prognostic factor for PFS [external validation; Aim-2; multivariable HR 2.21 (95% CI, 1.21–3.70; P = 0.003)].Conclusions:TGR has a role as a biomarker for monitoring response to therapy for early identification of treatment-induced changes and for early prediction of PFS and radiologic objective response.</div>

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