The relationship between dose to skeletal muscle area ratio and gemcitabine nab-paclitaxel toxicity in pancreatic ductal adenocarcinoma.

Abstract

492 Background: Combination gemcitabine and nab-paclitaxel (Gem-Nab-P) is a common regimen used to treat metastatic pancreatic ductal adenocarcinoma (PDAC). Toxicity is less than that associated with other combination metastatic regimens (FOLFIRINOX), but it is still associated with significant morbidity. Currently, Gem-Nab-P is dosed using estimated body surface area. This study investigates whether skeletal muscle assessment could be a useful tool in the dosing of Gem-Nab-P in metastatic PDAC. Methods: This study involved two sites and included patients who had received Gem-Nab-P between January 2013 and March 2017. A review of medical records was used to identify demographic, disease and first-cycle treatment information. Chemotherapy toxicity was defined as grade 3 or 4 adverse events using the National Cancer Institute Common Toxicity Criteria Adverse Events manual v4.0. Body composition analysis was performed on computed tomography scans at spinal level L3, using SliceOmatic software. SPSS software was used to for all statistical analysis, with a p value of < 0.05 considered significant. Results: We identified 52 patients treated with first-line Gem-Nab-P for PDAC. Median age was 65 years (57-73) and 24 (47%) were male. Median BMI at commencement of Gem-Nab-P was 24.7 kg/m2 (21.3-27.4) and 38 (58%) of the patients were myopenic before starting chemotherapy. Fourteen (27%) patients experienced toxicity during the first cycle of chemotherapy. Patients who experienced first-cycle chemotherapy-associated toxicity did not have a different median SkMA to those who did not (128.6 cm2 vs. 111.4 cm2, p= 0.2). There was also no difference in the gemcitabine dose to SkMA ratio (14.1 mg/cm2 vs. 14.4 mg/cm2, p=0.8), nab-paclitaxel to SkMA ratio (1.8 mg/cm2 vs. 1.8 mg/cm2, p=0.6) or combined dose equivalent to SkMA ratio (2.8 mg/cm2 vs. 2.9 mg/cm2, p=0.9) between the patients that experienced first cycle toxicity versus those that did not. Conclusions: This study suggests that a pancreatic cancer patient’s skeletal muscle area is unlikely to be a useful addition to conventional body surface area in the dosing of first line Gem-Nab-P, to reduce first-cycle toxicity.