The Food and Drug Administration (FDA) approved mitomycin for adult patients with low-grade upper tract urothelial cancer (LG-UTUC).

Efficacy determination was based on OLYMPUS (NCT02793128), an ongoing, single-arm, multicenter trial enrolling 71 patients with treatment-naïve or recurrent low-grade non-invasive UTUC with at least one measurable papillary tumour located above the ureteropelvic junction.

Patients who had larger tumours could have had prior tumour debulking.

Patients received weekly mitomycin 4 mg per mL instillations via ureteral catheter or nephrostomy tube for 6 weeks.

For patients with a complete response (CR) at 3 months, instillations were to be administered monthly for a maximum of 11 additional instillations.

The major efficacy outcome measures were CR and CR durability.

CR was defined as complete absence of tumour 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 CR three 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 CRs was evaluated at 3, 6, 9 and 12 months, following the CR determination.

Seven patients had documented recurrences and nineteen patients remained in CR at 12-months following CR 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 per mL instilled via ureteral catheter or nephrostomy tube, with total instillation volume based on volumetric measurements using pyelography, not exceeding 15 mL (60 mg mitomycin).

Source: The Food and Drug Administration (FDA)