Genetic Analysis-Guided Dosing of FOLFIRABRAX in Treating Patients With Advanced Gastrointestinal Cancer

PRIMARY OBJECTIVES: I. To determine the dose-limiting toxicity (DLT) rate in cycle #1 in each of three uridine diphosphate (UDP) glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1) genotype groups (\*1/\*1, \*1/\*28, \*28/\*28) using genotype-guided dosing of irinotecan (irinotecan hydrochloride) as part of the FOLFIRABRAX regimen. SECONDARY OBJECTIVES: I. To determine the cumulative dose of each chemotherapy drug (nab-paclitaxel \[paclitaxel albumin-stabilized nanoparticle formulation\], irinotecan, 5-FU \[fluorouracil\]) administered in each genotype group. II. To determine the response rates (in patients with measurable disease) by Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1) for each different disease (pancreatic cancer, biliary tract cancer, esophageal/gastric cancer, adenocarcinoma of unknown primary) treated in the study. OUTLINE: Patients receive FOLFIRABRAX comprising paclitaxel albumin-stabilized nanoparticle formulation intravenously (IV) over 0.5 hours, leucovorin calcium IV over 2 hours, irinotecan hydrochloride IV over 1.5 hours, and fluorouracil IV over 46 hours on days 1 and 15. Courses repeat every 4 weeks for up to 6 months in the absence of disease progression or unacceptable toxicity.