FDG PET analysis of treatment response in patients with pancreatic adenocarcinoma randomized to preoperative therapy with or without hydroxychloroquine.

Objectives To evaluate the therapeutic response in patients on 2 arms of a preoperative treatment protocol for pancreatic adenocarcinoma using FDG PET, CA 19-9, and histology.

Methods Baseline and follow-up FDG PET exams were obtained for 10 patients randomized to preoperative therapy with or without hydroxychloroquine (HCQ) who subsequently underwent surgical resection. Five patients received standard of care chemotherapy (2 cycles of gemcitabine/nab-paclitaxel) with HCQ and 5 patients received standard of care (SOC) chemotherapy alone. Analysis of therapeutic response was made by measuring changes in SUVmax and comparing HCQ and SOC treatment arms. Correlation was also made with CA 19-9 and pathologic assessment of histologic response¹.

Results 3 of 10 patients (HCQ=2, SOC=1) showed most improvement (>60% SUVmax reduction), 3 patients (HCQ=1, SOC=2) showed mild to moderate improvement (30-60% SUVmax reduction), 1 patient (SOC) showed mild improvement (<30% SUVmax reduction), and 3 patients (HCQ=2, SOC=1) showed no significant change. Means of SUVmax on baseline and follow-up scans were 7.6 & 3.0 and 4.8 & 2.2 for HCQ and SOC treatment arms, respectively. Mean post-therapy change in SUVmax was 61% and 54% for HCQ and SOC treatment arms, respectively. In addition, change in CA 19-9 levels correlated with histologic response to preoperative therapy (Evans score) and greater response was seen in the HCQ treatment arm (Evans Grades IIA-III) than in the SOC treatment arm (Evans Grades I-IIA).

Conclusions (1) Greater mean reduction in SUVmax on the HCQ treatment arm (-0.61 versus -0.54) suggests a more favorable response with HCQ than with SOC alone. (2) Additionally, early results show a positive correlation between change in CA 19-9 levels and histologic response by Evans criteria.