Dexamethasone is non-inferior to antihistamine plus dexamethasone premedication in preventing ramucirumab plus nab-paclitaxel infusion-related reactions in gastric cancer: a multicenter retrospective study.

PURPOSE: Ramucirumab (RAM) is recommended as premedication with H1-receptor antagonists (H1RA) to prevent infusion-related reactions (IRRs). However, RAM is a human antibody with a low incidence of IRRs. We evaluated the noninferiority of non-H1RA (dexamethasone [DEX] alone) premedication to H1RA (plus DEX) premedication in terms of IRRs in patients with gastric cancer receiving RAM plus nanoparticle albumin-bound paclitaxel (nab-PTX). METHODS: This was a noninferiority, multicenter, retrospective trial conducted in three Japanese centers to assess the incidence of IRRs in patients receiving RAM plus nab-PTX for gastric cancer between 2018 and 2023. Patients with gastric cancer receiving RAM plus nab-PTX were divided into groups with and without H1RA premedication. The incidence of IRRs was compared between the two groups. RESULTS: Ninety patients were evaluated, with non-H1RA and H1RA premedications in 43 and 47 cases, respectively. After the first dose of RAM, IRRs were not observed in either group. IRRs during the overall doses were 0% for non-H1RA premedication and 2.1% for H1RA premedication (90% confidence interval (CI): -5.6%-1.3% for each comparison). The upper limit of the 90% CI (1.3%) did not exceed the noninferiority margin (Δ) of + 10% and therefore met the noninferiority criteria. CONCLUSION: RAM plus nab-PTX for gastric cancer with DEX premedication may be possible without H1RA premedication.

The Inhibitory Effect of Ciprofloxacin on the ß-Glucuronidase-mediated Deconjugation of the Irinotecan Metabolite SN-38-G.

The enterohepatic recycling of a drug consists of its biliary excretion and intestinal reabsorption, which is sometimes accompanied by hepatic conjugation and intestinal deconjugation reactions. ß-Glucuronidase, an intestinal bacteria-produced enzyme, can break the bond between a biliary excreted drug and glucuronic acid. Antibiotics such as ciprofloxacin can reduce the enterohepatic recycling of glucuronide-conjugated drugs. In this study, we established an in vitro system to evaluate the ß-glucuronidase-mediated deconjugation of the irinotecan metabolite SN-38-G to its active SN-38 form and the effect of ciprofloxacin thereon. SN-38 formation increased in a time-dependent manner from 5 to 30 min. in the presence of ß-glucuronidase. Ciprofloxacin and phenolphthalein-ß-D-glucuronide (PhePG), a typical ß-glucuronidase substrate, significantly decreased SN-38-G deconjugation and, hence SN-38 formation. Similarly, the antibiotics enoxacin and gatifloxacin significantly inhibited the conversion of SN-38-G to SN-38, which was not observed for levofloxacin, streptomycin, ampicillin and amoxicillin/clavulanate. Ciprofloxacin showed a dose-dependent inhibitory effect on the ß-glucuronidase-mediated conversion of SN-38-G to SN-38 with a half-maximal inhibitory concentration (IC50 ) value of 83.8 µM. PhePG and ciprofloxacin afforded the inhibition in a competitive and non-competitive manner, respectively. These findings suggest that the reduction in the serum SN-38 concentration following co-administration of ciprofloxacin during irinotecan treatment is due, at least partly, to the decreased enterohepatic circulation of SN-38 through the non-competitive inhibition of intestinal ß-glucuronidase-mediated SN-38-G deconjugation.