Pembrolizumab Now FDA-Approved for Urothelial Carcinoma

Pembrolizumab Now FDA-Approved for Urothelial Carcinoma

The FDA approved pembrolizumab (Keytruda) for the treatment of patients with locally advanced or metastatic urothelial carcinoma who have disease progression during or following platinum-containing chemotherapy or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy.

Additionally, the FDA granted an accelerated approval to frontline pembrolizumab for patients with locally advanced or metastatic urothelial carcinoma who are not eligible for cisplatin-containing chemotherapy.

The approval in the second-line setting is based on the phase III KEYNOTE-045 study, in which single-agent pembrolizumab reduced the risk of death by 27% compared with chemotherapy in patients with advanced urothelial carcinoma whose disease progressed after prior treatment.¹

KEYNOTE-045 was designed for patients with locally advanced or metastatic, unresectable urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra who had progressed after 1 to 2 lines of platinum-based chemotherapy or who had experienced recurrence after 12 months of chemotherapy.

Overall, 542 patients were randomized to pembrolizumab (200 mg IV) every 3 weeks for 2 years versus chemotherapy consisting of either paclitaxel (175 mg/m²), docetaxel (75 mg/m²), or vinflunine (320 mg/m²) every 3 weeks for 2 years. The median age was 67 years in the pembrolizumab arm and 65 years in the chemotherapy cohort.

The treatment groups were well balanced for 4 key prognostic factors: hemoglobin level (>10 g/dL vs ≥10 g/dL); ECOG performance status (0/1 vs 2); liver metastases (yes vs no); and time from last chemotherapy dose (<3 vs ≥3 months).

The primary endpoints were overall survival (OS) and progression-free survival (PFS) in the total population and among participants with a combined positive score (CPS) ≥10% for PD-L1 expression. The CPS consisted of the percentage of PD-L1—positive tumor cells (TCs) and infiltrating immune cells relative to the total number of TCs as measured using the PD-L1 IHC 22C3 pharmDx assay on samples collected by core needle or excisional biopsies or in resected tissue.

The median OS for patients receiving pembrolizumab was 10.3 months (95% CI, 8.0-11.8 months) compared with 7.4 months (95% CI, 6.1-8.3 months) for those who received a chemotherapy regimen. The difference resulted in a hazard ratio of 0.73 (95% CI, 0.59-0.91; P = .004). The survival benefit was observed regardless of PD-L1 expression status.

PFS, however, was not superior with pembrolizumab by the time of data cutoff on September 7. The median PFS was 2.1 months (95% CI, 2.0-2.2 months) with the immunotherapy versus 3.3 months (95% CI, 2.3-3.5 months) with chemotherapy (P = .42).

The OS analysis of patients with CPS ≥10% showed that there was a 43% reduction in the risk of death with pembrolizumab compared with chemotherapy (HR, 0.57; 95% CI, 0.37 -0.88; P = .0048). The median OS was 8.0 months (95% CI, 5.0-12.3 months) with pembrolizumab versus 5.2 months (95% CI, 4.0-7.4 months) with chemotherapy.

The objective response rate was 21% with pembrolizumab compared with 11% with chemotherapy (P = .002). The complete response (CR) rate was also much higher with pembrolizumab at 7.0% compared with a 3.3% CR with chemotherapy.

The median duration of response in the pembrolizumab arm was not reached (range, 1.6+ to 15+ months) with an estimated 68% of responders considered likely to maintain a response for ≥12 months. By comparison, the median duration of response in the chemotherapy arm was 4.3 months (range, 1.4+ to 15.4+ months) with an estimated 35% likely to maintain a response for ≥12 months.

Patients who received pembrolizumab had fewer toxicities than those treated with chemotherapy. The incidence of treatment-related adverse events (AEs) was lower with pembrolizumab compared with chemotherapy, respectively, for any grade (60.9% vs 90.2%) and for AEs of grade 3-5 severity (15.0% vs 49.4%).

Treatment-related AEs occurring in ≥10% of participants were generally lower with pembrolizumab as opposed to chemotherapy, respectively, including for fatigue (13.9% vs 27.8%), nausea (10.9% vs 24.3%), diarrhea (9.0% vs 12.9%), asthenia (5.6% vs 14.1%), and anemia (3.4% vs 24.7% with chemotherapy).

The incidence of pruritus was higher in the pembrolizumab arm at 19.5% versus the chemotherapy group at 2.7%. Immune-related AEs that were higher with pembrolizumab compared with chemotherapy, respectively, included thyroid abnormalities (9.4% vs 1.6%), pneumonitis (4.1% vs 0.4%), and colitis (2.3% vs 0.4%).

Fifteen patients in the pembrolizumab arm and 28 patients in the chemotherapy group discontinued treatment due to a treatment-related AE. Each arm had 4 treatment-related deaths.

The accelerated approval of pembrolizumab in the first-line setting was based on the phase II KEYNOTE-052 trial, which enrolled 370 patients with locally advanced or metastatic urothelial carcinoma who were deemed not eligible for cisplatin-containing chemotherapy. In the single-arm trial, pembrolizumab was administered at a flat 200 mg dose intravenously on day 1 of each 3-week cycle for up to 24 months.

The median age for the first 100 patients was 75 years (range, 44-94), and 87% had visceral metastases at baseline. Patients had an ECOG performance status of 3 (1%), 2 (45%), 1 (30%), and 0 (24%).

At a median follow-up of 7.8 months, the ORR was 28.6% (95% CI, 24-34) and the median response duration was not reached (range 1.4+ to 17.8+ months). The CR rate was 7% and the partial response rate was 22%.

Results from the study presented at the 2016 ESMO Congress reported that AEs were consistent with prior trials exploring the PD-1 inhibitor.² Overall, 5 patients discontinued treatment due to a treatment-related AE. There were no deaths attributed to treatment-related AEs.

All-grade treatment-related AEs were experienced by 67% of patients and included fatigue (14%), pruritus (12%), pyrexia (8%), decreased appetite (7%), diarrhea (7%), rash (7%), chills (6%), hypothyroidism (6%), and nausea (6%). Grade 3/4 treatment-related AEs were experienced by 16% of patients, and included fatigue (4%), muscle spasms (2%), decreased appetite (1%), and diarrhea (1%).

The accelerated approval for frontline pembrolizumab in urothelial carcinoma is contingent on the results of a confirmatory trial.

Pembrolizumab has additional approved indications in melanoma, lung cancer, head and neck cancer, and Hodgkin lymphoma.

References

• Bellmunt J, de Wit R, Vaughn DJ, et al. Keynote-045: open-label, phase III study of pembrolizumab versus investigator’s choice of paclitaxel, docetaxel, or vinflunine for previously treated advanced urothelial cancer. Presented at: 2016 SITC Annual Meeting; November 9-13, 2016; National Harbor, MD. Abstract 470.
• Balar A, Bellmunt J, O’Donnell PH, et al. Pembrolizumab (pembro) as first-line therapy for advanced/unresectable or metastatic urothelial cancer: Preliminary results from the phase II KEYNOTE-052 study. Presented at: 2016 ESMO Congress; October 7-11, 2016; Copenhagen, Denmark. Abstract LBA32.