One-month stability study of a biosimilar of infliximab (Remsima®) after dilution and storage at 4°C and 25°C.

There is currently only one monoclonal antibody for which there is a biosimilar: infliximab, which was released onto the French market in 2015. The SPC for the biosimilar (Remsima®) are superimposable on those of the original, including 24-hour stability at both 4 and 25°C. The aim of our study was to determine the stability of this biosimilar during one month at 4 and 25°C. Three different batches at two concentrations (0.7mg/mL or 1.6mg/mL) were used. Physicochemical stability was evaluated by the following methods: turbidity, UV spectrometry, DLS, ion chromatography (CEX), gel exclusion chromatography (SEC), and light microscopy. The analyses were performed in triplicate. All methods used have been demonstrated to be valid for measuring antibody stability. There were no signs of physicochemical instability after seven days (on D7) of storage at 4 or 25°C. From D15, we observed slight changes by ion (percentage distribution of the different isoforms) and gel exclusion chromatography (percentage distribution of different polymers, i.e. dimers, oligomers). However, the areas under the curves were unchanged, and the proportions of polymers remained lower than 0.5%. Tertiary structure analysis also showed a change from D15. All observed changes are consistent with progressive oligomerization by hydrophobic interactions. In conclusion, the reconstituted biosimilar is stable for seven days at 4 and 25°C. Gradual oligomerization is observed from D15 but appears to be less than 0.5%, suggesting instability, albeit very limited, in the longer term; the practical consequences of this remain to be evaluated.

Inhibition of OCT2, MATE1 and MATE2-K as a possible mechanism of drug interaction between pazopanib and cisplatin.

We hypothesized that pazopanib is an inhibitor of cisplatin renal transporters OCT2, MATE1 and MATE2-K based on previous studies demonstrating an interaction between tyrosine kinase inhibitors and these transporters. Because several combinations of targeted therapies and cytotoxics are currently in development for cancer treatment, such an interaction is worth investigating. Experiments on HEK293 cells stably transfected to express OCT2, MATE1, MATE2-K or an empty vector (EV) were conducted. The inhibitory effect of pazopanib on these transporters was measured using the uptake of fluorescent substrate ASP+ and cisplatin in the different cell lines. The effect of pazopanib on cisplatin-induced cytotoxicity was also evaluated. A decrease of ASP+ uptake was observed in OCT2-HEK, MATE1-HEK and MATE2K-HEK cell lines after addition of pazopanib at increasing concentrations. Pazopanib inhibited cisplatin specific uptake in OCT2-HEK, MATE1-HEK and MATE2K-HEK lines. Cytotoxicity experiments showed that co-incubation of cisplatin with pazopanib multiplied up to 2.7, 2.4 and 1.6 times the EC50 values of cisplatin in OCT2-HEK, MATE1-HEK and MATE2K-HEK cell lines respectively, reaching about the same values as in EV-HEK cells. To conclude, pazopanib inhibits OCT2, MATE1 and MATE2-K, which are involved in cisplatin secretion into urine. The combination of these two drugs may lead to an interaction and increase the cisplatin-induced systemic toxicity. Given the wide variability of plasma pazopanib concentrations observed in vivo, the interaction may occur in a clinical setting, particularly in overexposed patients. The existence of a drug-drug interaction should be investigated when pazopanib is associated with a substrate of these transporters.