2509 - Evaluating [<sup>18</sup>F]Fluorodeoxyglucose (FDG) Uptake as a Prognostic Metric in Stage IV Lung Cancer Patients Being Treated with Pharmacological Ascorbate and Chemotherapy
Presenter(s)
A. R. Way1, M. O. Evbuomwan1, O. A. Alegi1, M. T. Roozeboom1, S. Rajan1, U. A. Uzomah1, M. Furqan2, B. G. Allen1, D. Spitz3, M. S. Petronek3, and M. Graham4; 1Department of Radiation Oncology, University of Iowa Health Care, Iowa City, IA, 2University of Iowa Health Care, Iowa City, IA, 3Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa Health Care, Iowa City, IA, 4Department of Nuclear Medicine, University of Iowa Health Care, Iowa City, IA
Purpose/Objective(s): Tumor glucose metabolism is thought to be intimately connected to redox metabolism through processes such as the pentose phosphate pathway for the generation of reducing equivalents (e.g., NADPH). Therefore, the use of [18F]Fluorodeoxyglucose (FDG) uptake as a surrogate marker of glucose metabolic rates may provide useful information into the relative sensitivity of tumors to redox metabolic therapies that have shown promise to enhance radiation and chemotherapy response (e.g., pharmacological ascorbate). This study is a retrospective secondary review of a single institutional phase II study of stage IV lung cancer patients who received pharmacological ascorbate and carboplatin/paclitaxel. The goal was to determine the prognostic value of FDG PET imaging in predicting patient outcomes (progression-free survival and overall survival). It is hypothesized that that FDG uptake correlates with patient outcomes (progression-free survival and/or overall survival) in patients with stage IV non-small cell lung cancer treated with pharmacological ascorbate and carboplatin/paclitaxel.
Materials/Methods: Thirty-eight patients participated in a single arm institutional phase II clinical trial for the treatment of stage IV non-small cell lung cancer, where eligible participants received 75 g ascorbate intravenously twice per week for 12 weeks in combination with carboplatin (AUC 6) and paclitaxel (200 mg/m2) every three weeks for 4 cycles. SUV-max, SUV-mean, SUV-volume, and SUV-total lesion activity above 3.5 from FDG PET/CT images were correlated with progression free survival and overall survival. Inclusion criteria of 18 years or older and SUV above 3.5. Thirty-four were included in final analysis since 4 died = 15 days of starting therapy. Statistical analysis was performed with the computer program GraphPad Prizm 10. Two-variable correlation was performed utilizing simple non-linear regression.
Results: Median follow up for 34 patients on treatment was 1-month for the first 6-months, then every 3 to 6 months after. Progression free survival had a median of 6.4 months and median overall survival was 2.1 years. Of note four patients are alive at an average of 7.5 years follow up. On evaluation of prognostic indices both FDG SUV-volume and FDG SUV-total lesion activity were negatively correlated with progression free survival (r = -0.35, p = 0.05, [95% CI, -0.63 to -0.0008] and r = -0.41, p = 0.04, [95% CI, -.70 to -.025], respectively). SUV-volume and SUV-total lesion activity did not show significant correlations with respect to overall survival (r = 0.15 p = 0.40, [95% CI, 0.11 to 0.68] and r = 0.19 p = 0.29, [95% CI, -0.48 to 0.18], respectively).
Conclusion: High FDG tumors appeared more resistant to therapy with ascorbate and progressed faster than tumors with lower FDG uptake. These data indicate that FDG uptake may serve as a novel, non-invasive approach to assess clinical response to treatment for patients receiving pharmacological ascorbate that warrant further investigation.