A low-dose pemetrexed-cisplatin combination regimen induces significant nephrotoxicity in mice.

Background: Pemetrexed is combined with cisplatin to treat cancer. Whether pemetrexed-cisplatin combination chemotherapy exacerbates cisplatin nephrotoxicity is unclear. Here, we investigated kidney injury in mice administered a non-lethal low-dose regimen of pemetrexed or cisplatin alone and compared it with a pemetrexed-cisplatin combination.

Methods: Mice were randomly divided into four groups and administered intraperitoneally the experimental drugs solubilized in captisol (sulfobutylether β-cyclodextrin). Group 1 received captisol, Group 2 pemetrexed (10 mg/kg), Group 3 cisplatin (1 mg/kg), and Group 4 pemetrexed (10 mg/kg) plus cisplatin (1 mg/kg). The mice were treated every other day for two weeks, three times per week. Glomerular filtration rate (GFR) was determined on the third day after the last treatment, followed by a necropsy.

Results: Whereas the relative kidney weight was comparable in the control vs. pemetrexed or cisplatin alone group, it was significantly increased in the combination group. Mice treated with cisplatin and pemetrexed-cisplatin combination exhibited reduced GFR. The pemetrexed-cisplatin combination caused significant increases in the plasma or urinary levels of kidney injury biomarkers, renal lipid peroxidation, and nitrosative stress compared with pemetrexed or cisplatin alone. Histopathology revealed that pemetrexed or cisplatin alone had minimal effects on the kidneys. By contrast, the pemetrexed-cisplatin combination caused tubular degeneration, dilatation, and granular casts. Live-cell imaging showed that the pemetrexed-cisplatin combination caused more severe apoptosis of primary renal epithelial cells than individual concentrations.

Conclusions: These findings suggest that combining pemetrexed and cisplatin causes oxidative kidney damage at individual doses that do not cause significant nephrotoxicity. Hence, the renal function of patients undergoing treatment with the pemetrexed-cisplatin combination needs extensive monitoring.