Can sirolimus oral solution cause proteinuria?

In a study evaluating maintenance kidney transplant patients switching from a calcineurin inhibitor (CNI) to sirolimus 6 to 120 months after transplantation, patients with the greatest urinary protein excretion before sirolimus switching were those with the greatest increase in protein excretion after the switch. New-onset kidney disease (nephrotic syndrome) was reported as a treatment-emergent adverse reaction in 2.2% of patients in the sirolimus-switching group, and nephrotic-range proteinuria (defined as a urinary protein to creatinine ratio >3.5) was reported in 9.2% of patients in the sirolimus-switching group. In some patients, an individual decrease in urinary protein excretion was observed after discontinuation of sirolimus.