On April 15, the U.S. Food and Drug Administration (FDA) approved mitomycin (Jelmyto) for adult patients with low-grade upper tract urothelial cancer.
Efficacy determination was based on OLYMPUS, an ongoing, single-arm, multicenter trial enrolling 71 patients with treatment-naive or recurrent low-grade noninvasive upper tract urothelial cancer with at least one measurable papillary tumor located above the ureteropelvic junction. Patients who had larger tumors could have had prior tumor debulking.
Patients received weekly mitomycin in 4 mg/mL instillations via ureteral catheter or nephrostomy tube for 6 weeks. For patients with a complete response at 3 months, instillations were to be administered monthly for a maximum of 11 additional instillations.
The major efficacy outcome measures were complete response and complete response durability. Complete response was defined as complete absence of tumor lesions 3 months after mitomycin initiation and was assessed by urine cytology and ureteroscopy. If warranted, a biopsy was performed.
Forty-one patients (58%) achieved a complete response 3 months following treatment initiation and were continued in follow-up; 29 patients received at least one dose of maintenance therapy.
Durability of response in those with complete responses was evaluated at 3, 6, 9 and 12 months, following the complete response determination. Seven patients had documented recurrences and 19 patients remained in complete response at 12 months following determination. The median response duration had not been reached (range = 0–18.8+ months).
The most common adverse reactions (≥ 20%) in patients who received mitomycin were ureteric obstruction, flank pain, urinary tract infection, hematuria, renal dysfunction, fatigue, nausea, abdominal pain, dysuria, and vomiting. Ureteric obstruction occurred in 58% of those receiving mitomycin and required ureteral stent placement in 88% of these patients.
The recommended mitomycin dose is 4 mg/mL instilled via ureteral catheter or nephrostomy tube, with total instillation volume based on volumetric measurements using pyelography, not exceeding 15 mL (60 mg of mitomycin).