18F-FDG PET/CT response in a phase 1/2 trial of nab-paclitaxel plus gemcitabine for advanced pancreatic cancer

Abstract

BackgroundPositron emission tomography (PET) is poised to become a useful imaging modality in staging and evaluating therapeutic responses in patients with metastatic pancreatic cancer (mPC). This analysis from a phase 1/2 study examined the utility of early PET imaging in patients with mPC treated with nab-paclitaxel plus gemcitabine.MethodsTumors were measured by [18F]2-fluoro-2-deoxyglucose PET/computed tomography (CT) in patients who received nab-paclitaxel 100 (n = 13), 125 (n = 38), or 150 (n = 1) mg/m2 plus gemcitabine 1000 mg/m2 on days 1, 8, and 15 of a 28-day cycle. Lesion metabolic activity was evaluated at baseline and 6 and 12 weeks postbaseline.ResultsFifty-two patients had baseline and ≥1 follow-up PET scan. The median maximum standardized uptake values per pancreatic lesion in the nab-paclitaxel 100 mg/m2 and 125 mg/m2 cohorts were 5.1 and 6.5, respectively. Among patients who had a metabolic response by PET, those who received nab-paclitaxel 125 mg/m2 had a 4-month survival advantage over those who received 100 mg/m2. All patients in the nab-paclitaxel 125 mg/m2 cohort experienced an early complete metabolic response (CMR; 34%) or partial metabolic response (PMR; 66%). In the nab-paclitaxel 125 mg/m2 cohort, investigator-assessed objective response rates were 77% and 44% among patients with a CMR and PMR, respectively, with no correlation between PET and CT response (Spearman r s = 0.22; P = 0.193). Patients in the nab-paclitaxel 125 mg/m2 cohort with a CMR experienced a significantly longer overall survival vs those with a PMR (median, 23.0 vs 11.2 months; P = 0.011), and a significant correlation was found between best percentage change in tumor burden by PET and survival: for each 1% decrease in PET score, the risk of death decreased by 2%.ConclusionsThe majority of primary pancreatic tumors and their metastases were PET avid, and PET effectively measured changes in tumor metabolic activity at 6 and 12 weeks. These results support the antitumor activity of nab-paclitaxel 125 mg/m2 plus gemcitabine 1000 mg/m2 for treating mPC and the utility of PET for measuring treatment response. Treatment response by PET analysis may be considered when evaluating investigational agents in mPC.Trial registrationNCT00398086.

Clinical Impact of 18F-FDG PET/CT in the Diagnostic Workup of Pancreatic Ductal Adenocarcinoma: A Systematic Review

“…Similar results were also reported by Kurahara et al and Nasr Shaban et al [37,38]. The reduction of SUVmax before and after chemotherapy, in terms of percentage, has been extensively reported by several authors, such as Chang et al [36], while others reported the utility of employing the European Organization for Research and Treatment of Cancer (EORTC) criteria for the definition of metabolic response to therapy [39]. Choi et al reported that, in 20 patients with locally advanced pancreatic cancer undergoing neoadjuvant induction chemotherapy followed by concurrent chemoradiotherapy (chemo-RT), the 1-year survival rate for the PET responders was 87% and for the PET non-responders it was 28% [40].…”