The efficacy of JELMYTO is based on the results of the OLYMPUS study (NCT02793128), an open-label, single-arm, multicenter trial that enrolled 71 patients with treatment-naïve or recurrent non-invasive low-grade upper tract urothelial cancer (LG-UTUC) with at least one measurable papillary tumor 5 to ≤ 15 mm located above the ureteropelvic junction; patients who had larger tumors could have had tumor debulking prior to treatment, in order to meet the criteria. Patients were excluded from the trial for a history of carcinoma in situ (CIS) in the urinary tract, invasive urothelial carcinoma within 5 years, high grade papillary urothelial carcinoma within 2 years; or for BCG treatment within 6 months of JELMYTO treatment. Following biopsy and prior to treatment, patients were required to have at least one remaining visible tumor with a diameter of at least 5 mm.

Patients received JELMYTO 4 mg per mL via ureteral catheter or nephrostomy tube with total instillation volume based on individualized volumetric measurements using pyelography with the intent to fill the renal pelvis. Patients were treated with 6 instillations once a week. Patients who maintained a complete response (CR) after the initial treatment period were allowed to proceed to the follow-up period. During the initial treatment period, 71 patients were treated with JELMYTO, of whom 41 were subsequently continued in the follow-up period. During the follow-up period, 29 patients received at least one dose of maintenance therapy.

The baseline demographic and disease characteristics for the trial population were: median age 71 years (range: 42-87 years); 68% male; 87% White; 90% Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 or 1 and 10% ECOG PS 2. The median number of papillary lesions subsequent to debulking and/or biopsy and prior to treatment was 1 lesion (range: 1, 5), the median diameter of the largest lesion was 8.0 mm (range: 5.0, 15.0), and the median total visible tumor burden was 10.0 mm (range: 5.0, 25.0). Twenty-six (37%) patients underwent tumor debulking during the six weeks preceding enrollment. Of 71 enrolled patients, 48% had tumors located in regions not amenable to endoscopic resection. General anesthesia was used in 37% of patients for at least one instillation during the treatment period and for 83% of patients for at least one instillation during the follow-up period. 

The major efficacy outcome measures were CR and durability of CR at 12 months after determination of CR based on ureteroscopic and local pathology assessment. CR was defined as complete absence of tumor lesions in the ipsilateral pyelocalyceal system at 3 months after initiation of JELMYTO by urine cytology and ureteroscopy. Biopsy was performed if warranted. Durability of response in patients with a CR was evaluated at 3, 6, 9 and 12 months following the initial assessment. Assessment of durability of CR subsequent to these evaluations was performed per local standards of care.

Forty-one patients (58%) achieved CR in the study (95% CI: 45%, 69%). Of the 41 patients who achieved CR, 23 (56%) of the patients remained at CR at the 12-month time point for assessment of durability, 8 (20%) experienced recurrence of disease, and 10 (24%) were unable to be evaluated (died, discontinued from the study, or were indeterminate for ongoing response). The median duration of response was not reached (range: 0, 18.8 months and ongoing). One patient, who achieved 6 months of durable CR, was diagnosed with metastatic urothelial carcinoma approximately 4.5 months after the last dose of study medication and died from the disease.